Professor Research Research Areas: Organic Chemistry Biological Chemistry Materials Chemistry and Nanoscience Research Interests: Photoswitchable bioactive compounds: Photoactivation of drugs, enzymes, and other bio-molecules allows for achieving of the spatial and temporal control of their action. We design and synthesize compounds that are inactive in the dark but are converted into bioactive form upon irradiation with light of an appropriate wavelength. One of our goals is to overcome the most common drawback of caged biomolecules, which are known to release bioactive substrates in the dark due to conventional or enzymatic hydrolysis. The non-photochemical reactions of photoactivatable compounds (hydrolysis, thermal decomposition, etc.) that we develop are very slow and do not result in activation of the substrate. Two-photon photochemistry: UV and visible light is efficiently absorbed by muscle tissues and only red and near infrared (NIR) radiation has sufficient depth of penetration in our bodies. Photons in this region, however, have relatively low energy, limiting the range of processes they can initiate. We are working on the development of the precursors that can be converted into an active form using nonresonant two-photon excitation. This approach allows us to use red/NIR light for photoactivation of UV-chromophores, while avoiding substrates sensitive to visible light, and therefore reducing accompanying phototoxicity. Photolabile protecting groups, known as “cages” in biochemistry, allow for the spatial and temporal control of substrate release, as well as “reagentless” deprotection. Our group designs novel types of "safety-catch" photo-cages suitable for protection of broad range of organic molecules. Mechanisms of light-induced reactions are investigated using state-of-the-art time-resolved IR (TIR) and UV-Vis (TUV) spectrometers. This data is then used in the design of novel photoswitchable bioactive compounds. Photo-"click" reactions: Connection (or ligation) of two fragments to make a larger molecule or structure, as well as labeling DNA, proteins, and even whole cells, are usually achieved with the help of the so-called “click chemistry”. This term describe a set of bimolecular reactions that meet the following criteria: reactions should be wide in scope but selective, produce high yield of the product, proceed with reasonable rate under mild conditions, and tolerate broad range of solvents. We work on the development of light-induced ligation techniques, which proceeds under ambient conditions and does not require additional reagents or catalyst. Selected Publications Selected Publications: 2018 Boudjemeline, M.; McNitt, C. D.; Popik, V.V.; Kostikov, A. P. “[18F]ODIBO: a universal prosthetic group for highly efficient radiolabelling of macromolecules via strain-promoted acetylene-azide cycloaddition” Org. Bioorg. Chem. 2018, 16(3), 363-366; DOI: 10.1039/C7OB02532G. 2017 Nainar, S. ; Kubota, M. ; McNitt, C. ; Tran, C. ; Popik, V. V. ; Spitale, R. C. Temporal Labeling of Nascent RNA Using Photoclick Chemistry in Live Cells. Journal of the American Chemical Society 2017, 139, 8090 - 8093; DOI: 10.1021/jacs.7b03121. McNitt, C. D. ; Cheng, H. ; Ullrich, S. ; Popik, V. V. ; Bjerknes, M. Multiphoton Activation of Photo-Strain-Promoted Azide Alkyne Cycloaddition “Click” Reagents Enables in Situ Labeling with Submicrometer Resolution. Journal of the American Chemical Society 2017, 139, 14029 - 14032. Bjerknes, M. ; Cheng, H. ; McNitt, C. D. ; Popik, V. V. Facile Quenching and Spatial Patterning of Cylooctynes via Strain-Promoted Alkyne–Azide Cycloaddition of Inorganic Azides. Bioconjugate Chemistry 2017, 28, 1560 - 1565. Whitehead, S. A. ; McNitt, C. D. ; Mattern-Schain, S. I. ; Carr, A. J. ; Alam, S. ; Popik, V. V. ; Best, M. D. Artificial Membrane Fusion Triggered by Strain-Promoted Alkyne–Azide Cycloaddition. Bioconjugate Chemistry 2017, 28, 923 - 932. Luo, W. ; Gobbo, P. ; McNitt, C. D. ; Sutton, D. A. ; Popik, V. V. ; Workentin, M. S. “Shine & Click” Photo-Induced Interfacial Unmasking of Strained Alkynes on Small Water-Soluble Gold Nanoparticles. Chemistry - A European Journal 2017, 25, 1052-1059. Sutton, M. V. ; McKinley, M. ; Kulasekharan, R. ; Popik, V. V. Photo-cleavable analog of BAPTA for the fast and efficient release of Ca 2+. Chemical Communications 2017, 53, 5598 - 5601. 2016 Brooks, K. ; Yatvin, J. ; McNitt, C. D. ; R. Reese, A. ; Jung, C. ; Popik, V. V. ; Locklin, J. Multifunctional Surface Manipulation Using Orthogonal Click Chemistry. Langmuir 2016, 32, 6600 - 6605. Sutton, D. A. ; Popik, V. V. Sequential Photochemistry of Dibenzo[ a,e]dicyclopropa[c,g][8]annulene-1,6-dione: Selective Formation of Didehydrodibenzo[ a,e][8]annulenes with Ultrafast SPAAC Reactivity. The Journal of Organic Chemistry 2016, 81, 8850 - 8857. Laradji, A. M. ; McNitt, C. D. ; Yadavalli, N. S. ; Popik, V. V. ; Minko, S. Robust, Solvent-Free, Catalyst-Free Click Chemistry for the Generation of Highly Stable Densely Grafted Poly(ethylene glycol) Polymer Brushes by the Grafting To Method and Their Properties. Macromolecules 2016, 49, 7625 - 7631. Sutton, D. A. ; Yu, S. - H. ; Steet, R. ; Popik, V. V. Cyclopropenone-caged Sondheimer diyne (dibenzo[a,e]cyclooctadiyne): a photoactivatable linchpin for efficient SPAAC crosslinking. Chem. Commun. 2016, 52, 553 - 556. 2015 Alam, S. ; Alves, D. S. ; Whitehead, S. A. ; Bayer, A. M. ; McNitt, C. D. ; Popik, V. V. ; Barrera, F. N. ; Best, M. D. A Clickable and Photocleavable Lipid Analogue for Cell Membrane Delivery and Release. Bioconjugate Chemistry 2015, 26, 1021 - 1031. 2014 Arumugam, S. ; Popik, V. V. Sequential “Click” – “Photo-Click” Cross-Linker for Catalyst-Free Ligation of Azide-Tagged Substrates. The Journal of Organic Chemistry 2014, 79, 2702 - 2708. Arnold, R. M. ; Patton, D. L. ; Popik, V. V. ; Locklin, J. A Dynamic Duo: Pairing Click Chemistry and Postpolymerization Modification To Design Complex Surfaces. Accounts of Chemical Research 2014, 140815135924000. Nekongo, E. E. ; Popik, V. V. Photoactivatable Fluorescein Derivatives Caged with a (3-Hydroxy-2-naphthalenyl)methyl Group. The Journal of Organic Chemistry 2014, 79, 7665 - 7671. Hui, J. Zhe; Zaki, A. Al; Cheng, Z. ; Popik, V. ; Zhang, H. ; Prak, E. T. Luning; Tsourkas, A. Facile Method for the Site-Specific, Covalent Attachment of Full-Length IgG onto Nanoparticles. Small 2014, 10, 3354-3363. Arumugam, S. ; Guo, J. ; Mbua, N. Eric; Friscourt, F. ; Lin, N. ; Nekongo, E. ; Boons, G. - J. ; Popik, V. V. Selective and reversible photochemical derivatization of cysteine residues in peptides and proteins. Chemical Science 2014, 5, 1591. Patel, J. M. ; Musa, M. M. ; Rodriguez, L. ; Sutton, D. A. ; Popik, V. V. ; Phillips, R. S. Mutation of Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase at Trp-110 affects stereoselectivity of aromatic ketone reduction. Organic & Biomolecular Chemistry 2014, 12, 5905. Pathak, R. K. ; McNitt, C. D. ; Popik, V. V. ; Dhar, S. Copper-Free Click-Chemistry Platform to Functionalize Cisplatin Prodrugs. Chemistry - A European Journal 2014, 20, 6861 - 6865. Arnold, R. M. ; McNitt, C. D. ; Popik, V. V. ; Locklin, J. Direct grafting of poly(pentafluorophenyl acrylate) onto oxides: versatile substrates for reactive microcapillary printing and self-sorting modification. Chem Commun (Camb) 2014, 50, 5307-9. Popik, V. V. ; Wright, A. G. ; Khan, T. A. ; Murphy, J. A. ; Gelat, F. ; Montchamp, J. - L. Encyclopedia of Reagents for Organic SynthesisHypophosphorous Acid; John Wiley & Sons, Ltd: Chichester, UK, 2014; pp. 1 - 11. 2013 Warden-Rothman, R. ; Caturegli, I. ; Popik, V. ; Tsourkas, A. Sortase-Tag Expressed Protein Ligation: Combining Protein Purification and Site-Specific Bioconjugation into a Single Step. Analytical Chemistry 2013, 85, 11090 - 11097. Elias, D. R. ; Poloukhtine, A. ; Popik, V. ; Tsourkas, A. Effect of ligand density, receptor density, and nanoparticle size on cell targeting. Nanomedicine: Nanotechnology, Biology and Medicine 2013, 9, 194 - 201. Arumugam, S. ; Orski, S. V. ; Mbua, N. E. ; Boons, G. - J. ; Locklin, J. ; Popik, V. V. Photo-click chemistry strategies for spatiotemporal control of metal-free ligation, labeling, and surface derivatization. Pure and Applied Chemistry 2013, 85, 1513. Kulyashova, A. E. ; Sorokoumov, V. N. ; Popik, V. V. ; Balova, I. A. An acetylene zipper–Sonogashira reaction sequence for the efficient synthesis of conjugated arylalkadiynols. Tetrahedron Letters 2013, 54, 2235-2238. Klán, P. ; Šolomek, T. ; Bochet, C. G. ; Blanc, A. ; Givens, R. ; Rubina, M. ; Popik, V. ; Kostikov, A. ; Wirz, J. Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy. Chemical Reviews 2013, 113, 119-191. 2012 Maitrani, C. ; Heyes, D. J. ; Hay, S. ; Arumugam, S. ; Popik, V. V. ; Phillips, R. S. Preparation and photophysical properties of a caged kynurenine. Bioorganic & Medicinal Chemistry Letters 2012, 22, 2737. Bostic, H. E. ; Smith, M. D. ; Poloukhtine, A. A. ; Popik, V. V. ; Best, M. D. Membrane labeling and immobilization via copper-free click chemistry. Chemical Communications 2012, 48, 1431-1433. Arumugam, S. ; Popik, V. V. Bichromophoric fluorescent photolabile protecting group for alcohols and carboxylic acids. Photochemical & Photobiological Sciences 2012, 11, 518-521. McNitt, C. ; Popik, V. Photochemical Generation of Oxa-Dibenzocyclooctyne (ODIBO) for Metal-Free Click Ligations. Organic & Biomolecular Chemistry 2012, 10, 8200-8202. Nekongo, E. E. ; Bagchi, P. ; Fahrni, C. ; Popik, V. 9-Aryl-9-Xanthenols: A Convenient Platform for the Design of Fluorimetric and Colorimetric pH Indicators. Organic & Biomolecular Chemistry 2012, 10, 9214-9218. Arumugam, S. ; Orski, S. V. ; Locklin, J. ; Popik, V. V. Photoreactive Polymer Brushes for High Density Surface Patterned Derivatization Using Diels-Alder Photo-click Reaction. Journal of the American Chemical Society 2012, 134, 179-182. Orski, S. V. ; Sheppard, G. R. ; Arumugam, S. ; Arnold, R. M. ; Popik, V. V. ; Locklin, J. Rate Determination of Azide Click Reactions onto Alkyne Polymer Brush Scaffolds: A Comparison of Conventional and Catalyst-free Cycloadditions for Tunable Surface Modification. Langmuir 2012, 28, 14693-14702. Arumugam, S. ; Popik, V. V. Attach, Remove, or Replace: Reversible Surface Functionalization Using Thiol-Quinone Methide Photoclick Chemistry. Journal of the American Chemical Society 2012, 134, 8408-8411. Yao, J. Z. ; Uttamapinant, C. ; Poloukhtine, A. A. ; Baskin, J. M. ; Codelli, J. A. ; Sletten, E. M. ; Bertozzi, C. R. ; Popik, V. V. ; Ting, A. Y. Fluorophore targeting to cellular proteins via enzyme-mediated azide ligation and strain-promoted cycloaddition. Journal of the American Chemical Society 2012, 134, 3720-3728. 2011 Sanders, B. C. ; Friscourt, F. ; Ledin, P. A. ; Mbua, N. E. ; Arumugam, S. ; Guo, J. ; Boltje, T. J. ; Popik, V. V. ; Boons, G. - J. Metal-Free Sequential [3 + 2]-Dipolar Cycloadditions using Cyclooctynes and 1,3-Dipoles of Different Reactivity. Journal of the American Chemical Society 2011, 133, 949-957. Arumugam, S. ; Chin, J. ; Scirrmacher, R. ; Popik, V. V. ; Kostikov, A. P. [18F]Azadibenzocyclooctyne ([18F]ADIBO): A biocompatible radioactive labeling synthon for peptides using catalyst free [3+2] cycloaddition. Bioorganic & Medicinal Chemistry Letters 2011, 21, 6987-6991 . Arumugam, S. ; Popik, V. V. Patterned Surface Derivatization Using Diels–Alder Photoclick Reaction. Journal of the American Chemical Society 2011, 133, 15730-15736. Cheng, Z. ; Elias, D. R. ; Kamat, N. P. ; Johnston, E. ; Poloukhtine, A. A. ; Popik, V. V. ; Hammer, D. A. ; Tsourkas, A. Improved Tumor Targeting of Polymer-based Nanovesicles Using Polymer-Lipid Blends. Bioconjugate Chemistry 2011, 22, 2010-2029. Vinogradova, O. V. ; Balova, I. A. ; Popik, V. V. Synthesis and Reactivity of Cinnoline-Fused Cyclic Enediyne. The Journal of Organic Chemistry 2011, 76, 6937-6941. Zhegalova, N. G. ; Popik, V. V. Wolff rearrangement of β-alkynyl-α-diazo-β-ketoesters: light-induced acetylene-allene isomerization and its use for activation of enediynes. Journal of Physical Organic Chemistry 2011, 24, 969-975. Arumugam, S. ; Popik, V. V. Light-Induced Hetero-Diels−Alder Cycloaddition: A Facile and Selective Photoclick Reaction. Journal of the American Chemical Society 2011, 133, 5573 - 5579. Sorokoumov, V. N. ; Popik, V. V. ; Balova, I. A. Access to 2,3-bis(buta-1,3-diynyl)pyridines. Mendeleev Commun. 2011, 21, 19-20. 2010 Popik, V. V. ; Poloukhtine, A. A. Preparation of cyclopropenones and the photochemical generation of cyclic alkynes therefrom, 2010. Arumugam, S. ; Popik, V. V. Dual Reactivity of Hydroxy- and Methoxy- Substituted o-Quinone Methides in Aqueous Solutions: Hydration versus Tautomerization. Journal of Organic Chemistry 2010, 75, 7338 - 7346. Poloukhtine, A. ; Rassadin, V. ; Kuzmin, A. ; Popik, V. V. Nucleophilic Cycloaromatization of Ynamide-Terminated Enediynes. Journal of Organic Chemistry 2010, 75, 5953 - 5962. Polukhtine, A. ; Karpov, G. ; Pandithavidana, D. R. ; Kuzmin, A. ; Popik, V. V. Photochemical Triggering of the Bergman and Myers-Saito Cyclizations. Australian Journal of Chemistry 2010, 63, 1099 - 1107. Orski, S. V. ; Poloukhtine, A. A. ; Arumugam, S. ; Mao, L. ; Popik, V. V. ; Locklin, J. High density orthogonal surface immobilization via photoactivated copper-free click chemistry. Journal of the American Chemical Society 2010, 132, 11024 - 11026. Kuzmin, A. ; Poloukhtine, A. ; Wolfert, M. A. ; Popik, V. V. Surface Functionalization Using Catalyst-Free Azide-Alkyne Cycloaddition. Bioconjugate Chemistry 2010, 21, 2076-2085. 2009 Arumugam, S. ; Popik, V. V. Photochemical Generation and the Reactivity of o-Naphthoquinone Methides in Aqueous Solutions. Journal of the American Chemical Society 2009, 131, 11892 - 11899. Pandithavidana, D. R. ; Poloukhtine, A. ; Popik, V. V. Photochemical Generation and Reversible Cycloaromatization of a Nine-Membered Ring Cyclic Enediyne. Journal of the American Chemical Society 2009, 131, 351 - 356. Kuzmin, A. V. ; Popik, V. V. Dual reactivity of a photochemically-generated cyclic enyne-allene. Chemical Communications (Cambridge, United Kingdom) 2009, 5707 - 5709. Kostikov, A. P. ; Malashikhina, N. ; Popik, V. V. Caging of Carbonyl Compounds as Photolabile (2,5-Dihydroxyphenyl)ethylene Glycol Acetals. Journal of Organic Chemistry 2009, 74, 1802 - 1804. Poloukhtine, A. A. ; Mbua, N. E. ; Wolfert, M. A. ; Boons, G. - J. ; Popik, V. V. Selective Labeling of Living Cells by a Photo-Triggered Click Reaction. Journal of the American Chemical Society 2009, 131, 15769 - 15776. 2008 Kulikov, A. ; Arumugam, S. ; Popik, V. V. Photolabile Protection of Alcohols, Phenols, and Carboxylic Acids with 3-Hydroxy-2-Naphthalenemethanol. Journal of Organic Chemistry 2008, 73, 7611 - 7615. Polukhtine, A. ; Karpov, G. ; Popik, V. V. Towards photoswitchable enediyne antibiotics: single and two-photon triggering of Bergman cyclization. Current Topics in Medicinal Chemistry (Sharjah, United Arab Emirates) 2008, 8, 460 - 469. Kostikov, A. P. ; Popik, V. V. Photolabile Protection of 1,2- and 1,3-Diols with Salicylaldehyde Derivatives. Organic Letters 2008, 10, 5277 - 5280. Karpov, G. ; Kuzmin, A. ; Popik, V. V. Enhancement of the Reactivity of Photochemically Generated Enediynes via Keto-Enol Tautomerization. Journal of the American Chemical Society 2008, 130, 11771 - 11777. 2007 Poloukhtine, A. ; Popik, V. V. Synthesis and Unusual Reactivity of N-Tosyl-4,5-benzoazacyclodeca-2,6-diyne, Yneamino-Containing Enediyne. Journal of the American Chemical Society 2007, 129, 12062 - 12063. Fu, N. ; Allen, A. D. ; Kobayashi, S. ; Tidwell, T. T. ; Vukovic, S. ; Arumugam, S. ; Popik, V. V. ; Mishima, M. Amino Substituted Bisketenes: Generation, Structure, and Reactivity. Journal of Organic Chemistry 2007, 72, 1951 - 1956. Kostikov, A. P. ; Popik, V. V. 2,5-Dihydroxybenzyl and (1,4-Dihydroxy-2-naphthyl)methyl, Novel Reductively Armed Photocages for the Hydroxyl Moiety. Journal of Organic Chemistry 2007, 72, 9190 - 9194. Karpov, G. V. ; Popik, V. V. Triggering of the Bergman Cyclization by Photochemical Ring Contraction. Facile Cycloaromatization of Benzannulated Cyclodeca-3,7-diene-1,5-diynes. Journal of the American Chemical Society 2007, 129, 3792 - 3793. Popik, V. V. ; Russell, A. E. Encyclopedia of Reagents for Organic SynthesisEthyl Diazoacetate; John Wiley & Sons, Ltd: Chichester, UK, 2007. 2006 Kuzmin, A. ; Popik, V. V. Synthesis and reactivity of 3,4-Benzocyclodeca-3,8-diene-1,5-diyne, a 10-membered enediyne containing additional endocyclic double bond. In; American Chemical Society, 2006; pp. SRM06-435. Poloukhtine, A. ; Popik, V. V. Two-Photon Photochemical Generation of Reactive Enediyne. Journal of Organic Chemistry 2006, 71, 7417 - 7421. Chang, J. A. ; Chiang, Y. ; Keeffe, J. R. ; Kresge, A. J. ; Nikolaev, V. A. ; Popik, V. V. The 2-Oxocyclobutanecarboxylic Acid Keto-Enol System in Aqueous Solution: A Remarkable Acid-Strengthening Effect of the Cyclobutane Ring. Journal of Organic Chemistry 2006, 71, 4460 - 4467. Poloukhtine, A. ; Popik, V. V. Mechanism of the Cyclopropenone Decarbonylation Reaction. A Density Functional Theory and Transient Spectroscopy Study. Journal of Physical Chemistry A 2006, 110, 1749 - 1757. Kostikov, A. P. ; Popik, V. V. (2-Hydroxyaryl)methyl ethers and esters as potential photocage for hydroxyl-containing compounds. In; American Chemical Society, 2006; pp. SRM06-436. Urdabayev, N. K. ; Popik, V. V. Synthesis and two-photon induced Wolff rearrangment of 2-diazo-1,3-diketone with high two-photon absorption cross section. In; American Chemical Society, 2006; p. ORGN-840. Bombuwala, K. ; Kinstle, T. ; Popik, V. ; Uppal, S. O. ; Olesen, J. B. ; Vina, J. ; Heckman, C. A. Colchitaxel, a coupled compound made from microtubule inhibitors colchicine and paclitaxel. Beilstein Journal of Organic Chemistry 2006, 2, No. 13, No pp. given. Kulikov, A. ; Popik, V. Design of a new photoremovable protecting (caging) group. In; American Chemical Society, 2006; p. ORGN-127. Urdabayev, N. K. ; Poloukhtine, A. ; Popik, V. V. Two-photon induced photodecarbonylation reaction of cyclopropenones. Chemical Communications (Cambridge, United Kingdom) 2006, 454 - 456. Poloukhtine, A. ; Popik, V. V. Synthesis and reactivity of 10-membered heterocyclic enediyne. In; American Chemical Society, 2006; pp. SRM06-437. 2005 Popik, V. V. The role of molecular geometry in the Wolff rearrangement of α-diazocarbonyl compounds - conformational control or structural constraints? Canadian Journal of Chemistry 2005, 83, 1382 - 1390. Urdabayev, N. K. ; Danilov, E. O. ; Popik, V. V. Development of photoreactive organic molecules with large two-photon absorption cross sections. In; American Chemical Society, 2005; p. ORGN-580. Poloukhtine, A. ; Popik, V. V. Photoswitchable enediynes: use of cyclopropenone as photocleavable masking group for the enediyne triple bond. Chemical Communications (Cambridge, United Kingdom) 2005, 617 - 619. Bogdanova, A. ; Perkovic, M. W. ; Popik, V. V. Structure and Photochemistry of 18-Diazo-1,4,7,10,13,16-hexaoxacyclononadeca-17,19-dione and Its Sodium and Potassium Complexes. Control of the Ground-State Conformation of 2-Diazo-1,3-dicarbonyl Fragment via Host-Guest Complexation. Journal of Organic Chemistry 2005, 70, 9867 - 9873. Urdabayev, N. K. ; Danilov, E. O. ; Popik, V. V. Development of Photoreactive Organic Molecules with Large Two-Photon Absorption Cross Sections. In; American Chemical Society, 2005; p. ONSUB-022. Poloukhtine, A. ; Popik, V. V. Application of Photochemical Decarbonylation of Cyclopropenones for the in Situ Generation of Reactive Enediynes. Construction of a Cyclopropenone-Containing Enediyne Precursor by Using a Cyclopropenone Acetal Building Block. Journal of Organic Chemistry 2005, 70, 1297 - 1305. 2004 Bogdanova, A. ; Popik, V. V. Experimental and Theoretical Analysis of the Photochemistry and Thermal Reactivity of Ethyl Diazomalonate and Its Diazirino Isomer. The Role of Molecular Geometry in the Decomposition of Diazocarbonyl Compounds. Journal of the American Chemical Society 2004, 126, 11293 - 11302. Karpov, G. V. ; Popik, V. V. Activation of enediynes by photochemical ring contraction: Design, synthesis and reactivity of cyclic enediynes containing diazodicarbonyl moiety. In; American Chemical Society, 2004; p. ORGN-367. Poloukhtine, A. A. ; Popik, V. Time-resolved investigation of the photodecarbonylation reaction of cyclopropenones. In; American Chemical Society, 2004; p. ORGN-309. Poloukhtine, A. ; Popik, V. V. Application of Photochemical Decarbonylation of Cyclopropenones for the In Situ Generation of Reactive Enediynes. In; American Chemical Society, 2004; p. GEN-313. Poloukhtine, A. A. ; Popik, V. V. En route to photoactivatable enediyne antibiotics. In; American Chemical Society, 2004; p. ORGN-414. Urdabayev, N. K. ; Popik, V. V. Wolff Rearrangement of 2-Diazo-1(2H)-Naphthalenone Induced by Nonresonant Two-Photon Absorption of NIR Radiation. Journal of the American Chemical Society 2004, 126, 4058 - 4059. 2003 Bogdanova, A. ; Popik, V. V. Experimental and Theoretical Investigation of Reversible Interconversion, Thermal Reactions, and Wavelength-Dependent Photochemistry of Diazo Meldrum's Acid and its Diazirine Isomer, 6,6-Dimethyl-5,7-dioxa-1,2-diaza-spiro[2,5]oct-1-ene-4,8-dione. Journal of the American Chemical Society 2003, 125, 14153 - 14162. Poloukhtine, A. ; Popik, V. V. Highly Efficient Photochemical Generation of a Triple Bond: Synthesis, Properties, and Photodecarbonylation of Cyclopropenones. Journal of Organic Chemistry 2003, 68, 7833 - 7840. Bogdanova, A. ; Popik, V. V. Wavelength-Dependent Photochemistry of Diazo Meldrum's Acid and Its Spirocyclic Isomer, Diazirino Meldrum's Acid: Wolff Rearrangement versus Isomerization. Journal of the American Chemical Society 2003, 125, 1456 - 1457. Chiang, Y. ; Gaplovsky, M. ; Kresge, J. A. ; Leung, K. H. ; Ley, C. ; Mac, M. ; Persy, G. ; Phillips, D. L. ; Popik, V. V. ; Roedig, C. ; Wirz, J. ; Zhu, Y. Photoreactions of 3-Diazo-3H-benzofuran-2-one; Dimerization and Hydrolysis of Its Primary Photoproduct, A Quinonoid Cumulenone: A Study by Time-Resolved Optical and Infrared Spectroscopy. Journal of the American Chemical Society 2003, 125, 12872 - 12880. Chang, J. A. ; Kresge, A. J. ; Nikolaev, V. A. ; Popik, V. V. The 2-Oxocyclohexanecarboxylic Acid Keto-Enol System in Aqueous Solution. Journal of the American Chemical Society 2003, 125, 6478 - 6484. 2002 Bogdanova, A. ; Popik, V. V. Comparison of the photochemical and thermal reactivity of diazo Meldrum's acid and 6,6-dimethyl-5,7-dioxa-1,2-diaza-spiro[2,5]oct-1-ene-4,8-dione: Its diazirine isomer. In; American Chemical Society, 2002; p. ORGN-471. Poloukhtine, A. A. ; Popik, V. V. Efficient generation of acetylenes by photodecarbonylation of cyclopropenones. In; American Chemical Society, 2002; p. ORGN-472. 2001 Bakulev, V. A. ; Chiang, Y. ; Kresge, A. J. ; Meng, Q. ; Morzherin, Y. Y. ; Popik, V. V. Flash Photolytic Generation and Study of the Enol of 2-Hydroxy-2-cyano-N-methylacetamide in Aqueous Solution, Leading to an Empirically-Based Estimate of the Keto-Enol Equilibrium Constant for the Parent Unsubstituted Acetamide in That Medium. Journal of the American Chemical Society 2001, 123, 2681 - 2682. Popik, V. V. Ethyl Diazoacetate. In; John Wiley & Sons, Ltd., 2001; p. No pp. given. Popik, V. V. Lithium Trichloropalladate. In; John Wiley & Sons, Ltd., 2001; p. No pp. given. Bogdanova, A. ; Popik, V. V. Photochemical ring opening of 7-benzoyl- and 7-methoxycarbonyldibenzonorcaradienes. Competing 1,2-hydrogen shift and cyclization reactions of 1,3-diradicals. Organic Letters 2001, 3, 1885 - 1888. Popik, V. V. ; Wright, A. G. ; Khan, T. A. ; Murphy, J. A. Hypophosphorous Acid. In; John Wiley & Sons, Ltd., 2001; p. No pp. given. Popik, V. V. Nitrogen Dioxide. In; John Wiley & Sons, Ltd., 2001; p. No pp. given. Bogdanova, A. ; Popik, V. Photochemical ring opening 7-acyl substituted dibenzonorcaradienes: Formation and reactions of 1,3-diradical. In; American Chemical Society, 2001; p. ORGN-449. Popik, V. V. Encyclopedia of Reagents for Organic SynthesisNitrogen Dioxide; John Wiley & Sons, Ltd: Chichester, UK, 2001. Popik, V. V. Encyclopedia of Reagents for Organic SynthesisLithium Trichloropalladate; John Wiley & Sons, Ltd: Chichester, UK, 2001. 2000 Chiang, Y. ; Eustace, S. J. ; Jefferson, E. A. ; Kresge, A. J. ; Popik, V. V. ; Xie, R. - Q. Flash photolysis of 4-diazoisochroman-3-one in aqueous solution. Hydration of the carbene produced by loss of nitrogen and ketonization of the enol hydration product. Journal of Physical Organic Chemistry 2000, 13, 461 - 467. 1999 Kresge, A. J. ; Lough, A. J. ; Popik, V. V. 1,3-Dihydrobenzo[c]thiophene-1-carboxylic acid. Acta Crystallographica, Section C: Crystal Structure Communications 1999, C55, iii, IUC9900139. Chiang, Y. ; Jefferson, E. A. ; Kresge, A. J. ; Popik, V. V. Flash Photolytic Investigation of 4-Diazoisothiochroman-3-one in Aqueous Solution: Observation of a Short-Lived Carboxylic Acid Enol. Journal of the American Chemical Society 1999, 121, 11330 - 11335. Andraos, J. ; Chiang, Y. ; Eustace, S. J. ; Kresge, A. J. ; Paine, S. W. ; Popik, V. V. ; Sung, K. Solvent isotope effect on the hydroxide-ion-catalyzed hydration of ketenes in aqueous solution. Canadian Journal of Chemistry 1999, 77, 459 - 462. Chiang, Y. ; Kresge, A. J. ; Popik, V. V. Diazoacetaldehyde: completion of the rate profile for hydration of its photo-Wolff rearrangement product, ketene, in aqueous solution and kinetics and mechanism of acid-catalyzed hydrolysis of the diazo aldehyde. Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry 1999, 1107 - 1109. Kresge, A. J. ; Lough, A. J. ; Popik, V. V. 2-Hydroxy-N-methylcyanoacetamide. Acta Crystallographica, Section C: Crystal Structure Communications 1999, C55, iii, IUC9900140. Kresge, A. J. ; Lough, A. J. ; Popik, V. V. 4-Hydroxyisochroman-3-one. Acta Crystallographica, Section C: Crystal Structure Communications 1999, C55, iii, IUC9900138. Carter, J. ; Fenwick, M. H. ; Huang, W. - W. ; Popik, V. V. ; Tidwell, T. T. Addition of the nitroxyl radical TEMPO to 1-naphthylketene: formation of an unusual adduct. Canadian Journal of Chemistry 1999, 77, 806 - 809. Chiang, Y. ; Kresge, A. J. ; Popik, V. V. Scavenging of Intermediates Formed in Photolysis of α-Diazocarbonyl Compounds and Hydroxycyclopropenones. Implication on the Mechanism of the Photo-Wolff Reaction. Journal of the American Chemical Society 1999, 121, 5930 - 5932. 1998 Chiang, Y. ; Kresge, J. A. ; Schepp, N. P. ; Popik, V. V. ; Rappoport, Z. ; Selzer, T. The acid dissociation constant of triphenylethenethiol, a simple thioenol, and that of its oxygen-enol analog. Canadian Journal of Chemistry 1998, 76, 657 - 661. Chiang, Y. ; Jefferson, E. A. ; Kresge, A. J. ; Popik, V. V. ; Xie, R. - Q. Conjugate addition of water to α-carbonylcarbenes. Journal of Physical Organic Chemistry 1998, 11, 610 - 613. 1997 Chiang, Y. ; Kresge, A. J. ; Popik, V. V. ; Schepp, N. P. The Mandelic Acid Keto-Enol System in Aqueous Solution. Generation of the Enol by Hydration of Phenylhydroxyketene and Phenylcarboxycarbene. Journal of the American Chemical Society 1997, 119, 10203 - 10212. Kresge, A. J. ; Popik, V. V. Unusual acid-catalyzed cyclization of 2,4,6-trimethoxydiazoacetophenone into 4,6-dimethoxy-3(2H)-benzofuranone. Mechanisms of intramolecular vs. intermolecular nucleophilic displacement of diazo group in protonated diazo ketones. In; Royal Society of Chemistry, 1997; p. No pp. given. Chiang, Y. ; Kresge, A. J. ; Nikolaev, V. A. ; Popik, V. V. The 1-oxo-2-cyclopentanecarboxylic acid keto-enol system in aqueous solution: generation of the enol by hydration of an acylketene. Journal of the American Chemical Society 1997, 119, 11183 - 11190. Andraos, J. ; Chiang, Y. ; Kresge, A. J. ; Popik, V. V. Flash Photolysis of 10-Diazo-9(10H)-phenanthrenone in Aqueous Solution. Hydration of Fluorenylideneketene and the Fluorene-9-carboxylic Acid Keto-Enol System. Journal of the American Chemical Society 1997, 119, 8417 - 8424. 1996 Kresge, A. J. ; Popik, V. V. Photochemical Wolff rearrangement of diazo Meldrum's acid and corresponding diazirine in aqueous solution. Generation of the enol of an alpha-oxocarboxylic acid. In; Royal Society of Chemistry, 1996; p. Paper 52. Chiang, Y. ; Kresge, A. J. ; Paine, S. W. ; Popik, V. V. Reactive species: ynols and ynamines. Journal of Physical Organic Chemistry 1996, 9, 361 - 370. 1995 Kresge, A. J. ; Mathew, L. ; Popik, V. V. Acid-catalyzed hydrolysis of phenyldiazoacetic acid. Effect of an α-diazo group on carboxylic acid acidity. Journal of Physical Organic Chemistry 1995, 8, 552 - 8. Wang, J. - L. ; Toscano, J. P. ; Platz, M. S. ; Nikolaev, V. ; Popik, V. Dicarbomethoxycarbene. A Laser Flash Photolysis Study. Journal of the American Chemical Society 1995, 117, 5477 - 83. Chiang, Y. ; Kresge, A. J. ; Popik, V. V. Flash Photolytic Generation and Study of Ynolate Ions and the Corresponding Ketenes in Aqueous Solution. Journal of the American Chemical Society 1995, 117, 9165 - 71. 1994 Toscano, J. P. ; Platz, M. S. ; Nikolaev, V. ; Popic, V. Carboethoxycarbene. A Laser Flash Photolysis Study. Journal of the American Chemical Society 1994, 116, 8146 - 51. Andraos, J. ; Kresge, A. J. ; Popik, V. V. Kinetics and Mechanism of the Isomerization of 1H-Indene-1-carboxylic Acid to 1H-Indene-3-carboxylic Acid in Aqueous Solution and Determination of Their Keto-Enol Equilibrium Constants and Acid Dissociation Constants of the Keto and Enol Forms. Implicatio. Journal of the American Chemical Society 1994, 116, 961 - 7. 1993 Popik, V. V. ; Nikolaev, V. A. Stereochemistry and thermal stability of diazo diketones. Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999) 1993, 1791 - 3. 1992 Nikolaev, V. A. ; Popik, V. V. Decomposition of 2-diazo-1,3-diketones: stereocontrol of the mechanism. Tetrahedron Letters 1992, 33, 4483 - 6. 1991 Popic, V. V. ; Korneev, S. M. ; Nikolaev, V. A. ; Korobitsyna, I. K. An improved synthesis of 2-diazo-1,3-diketones. Synthesis 1991, 195 - 8. Nikolaev, V. A. ; Popik, V. V. ; Korobitsyna, I. K. Chemistry of diazodicarbonyl compounds. IX. Conformational analysis of sterically hindered 2-diazo-1,3-diketones. Zhurnal Organicheskoi Khimii 1991, 27, 505 - 21. 1989 Nikolaev, V. A. ; Popik, V. V. Chemistry of diazo dicarbonyl compounds. VIII. Dipole moments and structure of aroylacetyl- and diaroyldiazomethanes. Zhurnal Organicheskoi Khimii 1989, 25, 1014 - 23. Popik, V. V. ; Nikolaev, V. A. Acylation of ketones with esters in the presence of a crown ether. Zhurnal Organicheskoi Khimii 1989, 25, 1810 - 11. Nikolaev, V. A. ; Popik, V. V. Conformational equilibrium in 2-diazo-1,3-diketones. Zhurnal Organicheskoi Khimii 1989, 25, 222 - 4.
