Publications:
| 166. | Triflone Chemistry 6 Mechanistic Aspects of the C-H Alkynylation Reaction of Acetylenic Triflones. Determination of Phenyl Versus Cyclohexyl Migratory Aptitude for a Vinylidine Carbene. Xiang, J. S.; Fuchs, P. L., Tetrahedron Lett. 1996, 37, 5269-5272. 13C-2 labeled phenyl ethynyl triflone undergoes regiospecific C-H
alkynylation upon reaction with cyclohexane. The 13C label is found to be
exclusively adjacent to the phenyl group in the product phenyl cyclohexyl acetylene,
consistent with cyclohexyl radical addition at the a-position. Control studies show
preferential phenyl migration from a vinylidine carbene, thus excluding the presence of
such an intermediate. |
| 169. | Triflone Chemistry 7 Alkenylation of C-H Bonds via Reaction with Vinyl and Dienyl Triflones. Stereospecific Synthesis of Trisubstituted Vinyl Triflones via Organocopper Addition to Acetylenic Triflones. Xiang, J.; Fuchs, P. L. J. Am. Chem. Soc. 1996, 118, 11986-11987. |
| 172. | Triflone Chemistry 8 Stereospecific Alkenylation of C-H Bonds via Reaction with b-Heteroatom-Functionalized Trisubstituted Vinyl Triflones. Xiang, J.; Jiang, W.; Gong, J.; Fuchs, P. L. J. Am. Chem. Soc. 1997, 119, 4123-4129. Aryl and alkyl beta-heteroatom-trisubstituted vinyl triflones react with THF
and cyclohexane to undergo trifluoromethyl radical-mediated C-H functionalization
reactions to afford E and Z beta-heteroatom-trisubstituted
olefins. Most reactions proceed with both high yield and high stereospecificity
(retention of configuration). beta-Substituents which have been employed in this
study are iodine, bromine, fluorine, benzoate, ethylcarbonate, and phthalimide.
b-Substituents bearing powerful electron-releasing groups suchs as alkoxy or amino render
the vinyl triflone unreactive. |
| 170. | Triflone Chemistry 9 Alkynylation of Aldehydic C-H Bonds via Reaction with Acetylenic Triflones. Gong, J.; Fuchs, P. L. Tetrahedron Lett. 1997, 38, 787-790. Reaction
of aldehydes with acetylenic triflones affords acetylenic ketones and alkylated acetylenes
via the intermediacy of acyl radicals, the product ratio being highly dependent upon
aldehyde structure and reaction conditions. |
| 174. | Triflone Chemistry 10 Scope and Limitations of Functionalized Acetylenic Triflones in the Direct Alkynylation of C-H Bonds. Xiang, J.; Jiang, W.; Fuchs, P. L. Tetrahedron Lett. 1997, 38, 6635-6638. Reactions of TIPS-substituted acetylenic triflones extends the versatility of
the trifluoromethyl radical mediated C-H alkynylation reaction. Alkynes bearing acetylenic
or propargylic oxygen functionality cannot be prepared, but silyl ethers or chlorides in
remote positions may be carried through the reaction. Crown ethers are successfully
monofunctionalized and distal bis-acetylenes may be employed in the title reaction. |
| 181. | Triflone Chemistry 11 Use of Allylic Triflones for Allylation of C-H Bonds. Xiang, J.; Evarts, J.; Rivkin, A.; Curran, D.P.; Fuchs, P.L. Tetrahedron Lett. 1998, 39, 4163-4166. |
| 182. | Triflone Chemistry 12 Chemospecific Alkynylation of Organic Iodides. Xiang, J.; Fuchs, P.L. Tetrahedron Lett. 1998, 39, 8597-8600. |