Lewis Base Catalyzed, Enantioselective, Intramolecular Sulfenoamination of Olefins

Abstract

A method for the enantioselective, intramolecular sulfenoamination of various olefins has been developed using a chiral BINAM-based selenophosphoramide, Lewis base catalyst. Terminal and trans disubstituted alkenes afforded pyrrolidines, piperidines, and azepanes in high yields and high enantiomeric ratios via enantioselective formation and subsequent stereospecific capture of the thiiranium intermediate with the pendant tosyl-protected amine.

Mechanistic, crystallographic, and computational studies on the catalytic, enantioselective sulfenofunctionalization of alkenes

“…of 98.6:1.4, whereas 4ea gave only a moderate selectivity which is in line with stereochemical outcome previously observed with terminal alkene 1c . Apart from the sulfenoetherification, we were able to demonstrate the benefit of 2j in a sulfenoamination reaction 25 using alkenyl sulfonamide 1f . Again an enhanced enantioselectivity was noticed with 2j forming product 4fj in 94.3:5.7 e.r.…”

“…In addition to the use of hydroxyl groups in sulfenoetherification reactions 21 , electron-rich arenes have been deployed in carbosulfenylations of olefins affording trans -tetrahydronaphthalenes with complete diastereospecificity and high enantiomeric ratios 22,23,24 . More recently, we have extended our protocol to tosyl-protected amines that can be engaged in sulfenoamination reactions yielding enantioenriched nitrogen heterocycles 25 .…”

Catalytic, Enantioselective, Intramolecular Sulfenoamination of Alkenes with Anilines

“…20 The electronic properties of the amine were varied by installing different protecting groups on the amine. Also, the tether length between the alkene and amine was varied to examine the accessibility of medium-sized rings.…”

“…20 Therefore, it was logical that anti -2,3-disubstituted tetrahydroquinolines could be analogously accessed by substituting aniline nucleophiles in place of the established amines. Anilines are unique functional groups in both their steric and electronic properties when compared to the aliphatic amines.…”

Enantioselective Trifluoromethylthiolating Lactonization Catalyzed by an Indane‐Based Chiral Sulfide

“…[18] Owing to the involvement of ac halcogenide in the catalytic cycle,w e envisioned that chiral trifluoromethylated products could be formed through chiral chalcogenide catalysis (Scheme 1b). Compared to the asymmetric incorporation of SCF 3 groups by S N 2p athways, [13][14][15][16] the enantioselective trifluoromethylthiolation of alkenes is more challenging.According to studies of enantioselective alkene bromo-and chalcofunctionalizations by the groups of Denmark [19] and Yeung, [20] the enantioselectivities can be heavily affected by two issues:racemization of the iranium ion through olefin-to-olefin degeneration and the racemization derived from which nucleophilic partners may capture the thiiranium or seleniranium species.T oovercome these possible racemization problems,wec onsidered the use of abifunctional catalyst that would stabilize the intermediary iranium ion. Thep roposed bifunctional catalyst possesses achalcogenide group as the Lewis base and an NH moiety as the hydrogen-bond donor.H erein, we report an efficient approach for the asymmetric trifluoromethylthiolation of alkenes that is based on the use of such an indane-based chiral bifunctional sulfide catalyst and an ew electrophilic SCF 3 reagent.…”