A Convenient Method for the Synthesis of β,γ-Unsaturated Amines from Alkenes via α,β-Unsaturated Diphenylsulfonium Salts

Abstract

1,1-Disubstituted and trisubstituted alkenes were converted into the corresponding β,γ-unsaturated amines 4 via three steps: the initial formation of α,β-unsaturated diphenylsulfonium triflates 2 from alkenes and diphenyl(trifluoromethanesulfonyloxy)sulfonium trifluoromethanesulfonate (1), followed by double bond migration of 2 to β,γ-unsaturated sulfonium triflates 3 with primary or secondary amines, and successive nucleophilic substitution of 3 with these amines.

A Facile One-Pot Benzylation of Sodium Enolates Using Trifluoromethanesulfonic Anhydride and Diphenyl Sulfoxide

“…We have previously reported that diphenyl sulfide bis(trifluoromethanesulfonate) reacts with styrene to generate the corresponding active sulfonium intermediate, which in turn reacts with amines to afford aziridines or b,g-unsaturated amines. 12,13) Therefore, formation of an alkoxy diphenyl sulfonium intermediate was anticipated upon treatment of an alcohol with diphenyl sulfide bis(trifluoromethanesulfonate). Initially, reaction of 4-methoxybenzyl alcohol with sodium dimethyl malonate was studied as a model system; that is, the diphenyl alkoxy sulfonium intermediate was generated by adding 1.2 eq of 4-methoxybenzyl alcohol to a mixture of trifluoromethanesulfonic anhydride and diphenyl sulfoxide in tetrahydrofuran (THF) at Ϫ78°C.…”

Sulfur-Mediated Reactions through Sulfonium Salts and Ylides

“…It should be noted that a similar sulfur mediated allylic C-H amination of 1,1-disubstituted and trisubstituted alkenes was reported by Mukaiyama group back in 2003. 18…”

“…It should be noted that a similar sulfur-mediated allylic C-H amination of 1,1-disubstituted and trisubstituted alkenes was reported by Mukaiyama back in 2003. 18 When we conducted this reaction with allylbenzene and isopropylamine (Scheme 4), the originally expected product 5a was only isolated in a low 8% yield; however, two undesired products were obtained in higher yields, i.e., the rearranged allylic C-H amination product 5b and the four-membered ring azetidine product 5c. The most plausible explanation involves an anti-Markovnikov rearrangement from a secondary carbocation A toward primary carbocation B or primary triflate C. Intramolecular electrostatic repulsion in the less stable dicationic sulfonium salt A could be the thermodynamic driving force for such an unusual rearrangement from a more substituted carbocation to a less substituted one.…”

New methods for the preparations of 2-aryl aziridines, α-imido styrenes, and allyl amines from olefins via diphenylvinylsulfonium triflates

“…(ii) α-imidostyrenes 3 6 from styrene derivatives via 1, and (iii) allylamines 5 7 from alkenes via unusual conversion of 1 to allylsulfonium salts 4. In this article, we would like to describe these three reactions in detail.…”