jo4023765_si_002.cif (71.44 kB)
Catalytic, Enantioselective, Intramolecular Carbosulfenylation of Olefins. Preparative and Stereochemical Aspects
dataset
posted on 2014-01-03, 00:00 authored by Scott E. Denmark, Alex JaunetThe
first catalytic, enantioselective, intramolecular carbosulfenylation
of isolated alkenes with aromatic nucleophiles is described. The combination
of N-phenylsulfenylphthalimide, a chiral
selenophosphoramide derived from BINAM, and ethanesulfonic
acid as a cocatalytic Brønsted acid induced an efficient and
selective cyclofunctionalization of various alkenes (aliphatic
and aromatic) tethered to a 3,4-methylenedioxyphenyl
ring. Under these conditions, 6-phenylthio-5,6,7,8-tetrahydronaphthalenes
are formed diastereospecifically in good yields (50–92%)
and high enantioselectivities (71:29–97:3 er). E-Alkenes reacted much more rapidly and with much higher
selectivity than Z-alkenes, whereas electron-rich
alkenes reacted more rapidly but with comparable selectivity to electron-neutral
alkenes and electron-deficient alkenes. The Brønsted acid played
a critical role in effecting reproducible enantioselectivity. A model
for the origin of enantioselectivity and the dependence of rate and
selectivity on alkene structure is proposed along with a rationale
for the site selectivity in reactions with monoactivated arene
nucleophiles.