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Strained cyclic cumulenes have been of interest to science since prehistoric times! For evidence to support this astonishing claim, check this reference: |
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Strained Molecules
We have long been interested in the structural limitations in hydrocarbons with strained pi bonds. Some of the amazing structures we have investigated are shown below.
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Strained cyclic cumulenes have been of interest to science since prehistoric times! For evidence to support this astonishing claim, check this reference: |
M. W. Schmidt, R. O. Angus, Jr. and R. P. Johnson*, "Small-Ring Cyclic Allenes: An Ab Initio Study of 1,2-Cyclohexadiene", J. Am. Chem. Soc., 104, 6838-6839 (1982)
R. O. Angus, Jr. and R. P. Johnson*, "Small-Ring Cyclic Cumulenes: The Structure and Energetics of Cyclic Butatrienes and the Synthesis of 1,2,3-Cyclononatriene", J. Org. Chem., 49, 2880-2883 (1984).
R. O. Angus, Jr., M. W. Schmidt and R. P. Johnson*, "Small-Ring Cyclic Cumulenes: Theoretical Studies of the Structure and Barrier to Inversion in Cyclic Allenes", J. Am. Chem. Soc., 107, 532-537 (1985).
J. D. Price and R. P. Johnson*, "Small-Ring Cyclic Cumulenes: Synthesis of a Kinetically Stable 1,2- Cyclooctadiene", J.D. Price and R.P. Johnson*, Tetrahedron Letters 27, 4679 4682 (1986).
R. P. Johnson "The Structure and Energetics of Cyclic Alkenes, Alkynes, and Cumulenes", a chapter for "Molecular Structures and Energetics", Volume 3, Verlag-Chemie International, J.F. Liebman and A. Greenberg, (Eds.), 1986.
R. P. Johnson, "Strained Cyclic Cumulenes", Chem. Rev., 89, 1111 1124 (1989).
W. C. Shakespeare and R. P. Johnson*, "1,2,3Cyclohexatriene and Cyclohexen3-yne: Two New Highly Strained C6H6 Isomers", J. Am. Chem. Soc.,112, 8578 8579 (1990).
Manli Zheng, Kenneth J. DiRico, Mary M. Kirchhoff, Kristine Phillips, Lisa M. Cuff and Richard P. Johnson*, "Photorearrangements of Acyclic Conjugated Enynes: A Photochemical Analogue of the Bergman Rearrangement" Journal of the American Chemical Society, 115, 1216712168 (1993).
Richard P. Johnson* and Kimberly J. Daoust, "Interconversions of Cyclobutyne, Cyclopentyne, Cyclohexyne and Their Corresponding Cycloalkylidenecarbenes" Journal of the American Chemical Society 117, 362367 (1995)
Richard P. Johnson* and Kenneth DiRico, "Ab Initio Conformational Analysis of transCyclohexene", J. Org. Chem., 60, 1074 1076 (1995).
Susana Hernandez, Mary M. Kirchhoff, Stephen G. Swartz Jr. and Richard P. Johnson*, "1,2,3-Cyclooctatriene", Tetrahedron Letters. 37, 4907 - 4910 (1996).
Richard P. Johnson* and Kimberly J. Daoust, "Electrocyclic Ring Opening Modes of Dewar Benzenes: Ab Initio Predictions for Möbius Benzene and trans-Dewar Benzene as New C6H6 Isomers", J. Am. Chem. Soc. , 1996, 118, 7381 - 7385.
John E. Mabry and Richard P. Johnson* "Beyond the Brown Rearrangement: A Trialene Mechanism for Long Range Carbon Automerization in Conjugated Polyynes", J. Am. Chem. Soc. 2002, 124, 6497 - 6501.
Organic Photochemistry
In earlier work, we investigated the photoreactions of allenes and discovered a rich variety of chemistry. More recently, we have studied enyne photochemistry and found a four-electron homolog of the Bergman rearrangement. Carbene photoextrusion from cyclopropanated phenanthrenes provides a general route to carbenes.
R. P. Johnson, "Cumulene Photochemistry", Organic Photochemistry, Volume 7, Chpt. 2, A. Padwa, Editor, 1985.
M. W. Klett and R.P. Johnson*, "Cumulene Photochemistry: Photorearrangements of Tetraphenyl and Triphenyl C3 Isomers", J. Am. Chem. Soc., 107, 3963-3971 (1985).
T. J. Stierman and R.P. Johnson*, "Cumulene Photochemistry: Singlet and Triplet Photorearrangements of 1,2-Cyclononadiene", J. Am. Chem. Soc., 107, 3971-3980 (1985).
M. W. Klett and R. P. Johnson*, "Photogeneration of Triphenyl C3 Radical Cations: Pathways Involving Deprotonation and Nucleophilic Addition", J. Am. Chem. Soc., 107, 6615-6620 (1985).
M.W. Klett and R.P. Johnson*, "Cumulene Photochemistry: Photoaddition of Neutral Methanol to Phenylallenes", Tetrahedron Letters, 1107-1110 (1983).
T.J. Stierman and R.P. Johnson*, "Cumulene Photochemistry: Photorearrangement of 1,2-Cyclononadiene to a Bicyclic Cyclopropene", J. Am. Chem. Soc., 105, 2492-2493 (1983).
M. W. Klett and R. P. Johnson*, "Cumulene Photochemistry: Phenyl and Hydrogen Migration in Phenylallene Photoreactions", Tetrahedron Letters, 2523-2526 (1983).
B. Lam and R. P. Johnson*, "Polarized Nonvertical Excited States: A FORS-MCSCF and CI Study of Torsion and Bending in Allene", J. Am. Chem. Soc., 105, 7479-7483 (1983).
J. E. Chateauneuf*, R. P. Johnson* and M. M. Kirchhoff, "Absolute Kinetics of Dichlorocarbene in Solution", J. Am. Chem. Soc., 112, 3217 3218 (1990).
J. D. Price and R. P. Johnson*, "Cumulene Photochemistry: Evidence for Cis and Trans Cyclopropylidene Intermediates in the Photoreactions of 1,2-cyclodecadiene", J. Am. Chem. Soc., 107, 2187-2189 (1985).
L. M. Tolbert*, Md. N. Islam, R. P. Johnson*, P. M. Loiselle and W. C. Shakespeare, "Carbanion Photochemistry: A New Photochemical Route to Strained Cyclic Allenes", J. Am. Chem. Soc.,112, 64166417 (1990).
Manli Zheng, Kenneth J. DiRico, Mary M. Kirchhoff, Kristine Phillips, Lisa M. Cuff and Richard P. Johnson*, "Photorearrangements of Acyclic Conjugated Enynes: A Photochemical Analogue of the Bergman Rearrangement" Journal of the American Chemical Society, 115, 1216712168 (1993).
Reactive Intermediates
R. P. Johnson, "An Ab Initio Molecular Orbital Study of the Phenyl Radical", J. Org. Chem., 49, 4857-4859 (1984).
J. E. Chateauneuf*, R. P. Johnson* and M. M. Kirchhoff, "Absolute Kinetics of Dichlorocarbene in Solution", J. Am. Chem. Soc., 112, 3217 3218 (1990).
Marc Robert, John P. Toscano, Matthew S. Platz*, Sarah C. Abbot, Mary M. Kirchhoff, and Richard P. Johnson*, "A Laser Flash Photolysis Study of Chlorocarbene", J. Physical Chem. 1996, 100, 18426 - 18430.
Marc Robert, Igor Likhotvorik, Matthew S. Platz*, Sarah C. Abbot, Mary M. Kirchhoff, and Richard P. Johnson*, "A Laser Flash Photolysis Study of Alkylhalocarbenes Generated from Non-Nitrogenous Precursors", J. Physical Chem. 1998, 102, 1507-1512.
M. Nigam, M. S. Platz*, B. M. Showalter, J. P. Toscano, R. P. Johnson*, S. C. Abbot and M. M. Kirchhoff, "Generation and Study of Benzylchlorocarbene from a Phenanthrene Precursor", J. Am. Chem. Soc. 1998, 120, 8055 - 8059.
New Diels-Alder Chemistry
The Diels-Alder reaction is not limited to dienes. We have shown that enynes and even diynes can act as the four-electron component. With three triple bonds, this leads to benzyne. Contrary to the textbook view, we have also found a perfectly good reaction pathway for reaction of s-trans-1,3-butadiene with ethylene to give trans-cyclohexene. Recent work also involves collaborative studies with John Porco on the synthesis of torreyanic acid and panapophenanthrin.
R.O. Angus, Jr. and R.P. Johnson*, "A Butatriene Cycloaddition Equivalent Approach to the Multiple Linear Homologation of Six- Membered Rings and the Synthesis of Benzocyclobutenes", J. Org. Chem., 48, 273-277 (1983).
Richard C. Burrell, Kimberly J. Daoust, Alexander Z. Bradley, Kenneth J. DiRico and Richard P. Johnson* "Strained Cyclic Cumulene Intermediates in Diels-Alder Cycloadditions of Enynes and Diynes", Journal of the American Chemical Society, 118, 4218 - 4219 (1996).
Alexander Z. Bradley and Richard P. Johnson*, "Thermolysis of 1,3,8-Nonatriyne: Evidence for Intramolecular Cycloaromatization to a Benzyne Intermediate", J. Am. Chem. Soc. , 1997, 119, 9917 - 9918.
Martin G. Kociolek and Richard P. Johnson, "Intramolecular Thermal Cyclotrimerization of an Acyclic Triyne: An Uncatalyzed Process", Tetrahedron Letters , 1999, 40, 4141 - 4144.
Alexander Z. Bradley, Martin G. Kociolek and Richard P. Johnson, "Conformational Selectivity in the Diels-Alder Cycloaddition: Predictions for Reactions of s-trans-1,3-Butadienes " J. Org. Chem. 2000, 65, 7134 - 7138.
Chaomin Li, Richard P. Johnson and John A. Porco, Jr. "Total Synthesis of the Quinone Epoxide Dimer (+)-Torreyanic Acid: Application of a Biomimetic Oxidation/ Electrocyclization/Diels-Alder Dimerization Cascade", J. Am. Chem. Soc. 2003, 125, 5095-5106.
Xiaoguang Lei, Richard P. Johnson and John A. Porco Jr., "Total Synthesis of the Ubiquitin-Activating Enzyme Inhibitor (+)-Panepophenanthrin", Angew. Chem. Int. Ed. 2003, 42, 3913 3917.
Other Topics
Other current projects include: 1) Mechanistic studies on the fragmentation mechanisms in MALDI mass spectra of carbohydrates 2) Synthesis of degradable polymers 3) Mechanistic studies on the environmental formation of halomethanes.
J. D. Price and R. P. Johnson*, "Thermal Rearrangements of Cyclic Allenes via Retro-Ene Reactions:, Tetrahedron Letters, 2499-2502 (1985).
R. O. Angus, Jr. and R. P. Johnson*, "Columnar Homoconjugation", J. Org. Chem., 53, 314 317 (1988).
D. W. Kurtz* and R. P. Johnson, " A Valence Isomer Trapping Procedure for Introductory Organic Laboratory: Synthesis of a Homobarrelene Derivative", J. Chem. Educ., 66, 873874 (1989).
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