ja8b11395_si_001.pdf (6.07 MB)
Catalytic Hydrothiolation: Counterion-Controlled Regioselectivity
journal contribution
posted on 2019-02-08, 19:49 authored by Xiao-Hui Yang, Ryan T. Davison, Shao-Zhen Nie, Faben A. Cruz, Tristan M. McGinnis, Vy M. DongIn
this Article, we expand upon the catalytic hydrothiolation
of 1,3-dienes to afford either allylic or homoallylic sulfides with
high regiocontrol. Mechanistic studies support a pathway in
which regioselectivity is dictated by the choice of counterion
associated with the Rh center. Non-coordinating counterions, such
as SbF6–, allow for η4-diene coordination to Rh complexes and result in allylic sulfides.
In contrast, coordinating counterions, such as Cl–, favor neutral Rh complexes in which the diene binds η2 to afford homoallylic sulfides. We propose mechanisms that
rationalize a fractional dependence on thiol for the 1,2-Markovnikov
hydrothiolation while accounting for an inverse dependence on
thiol in the 3,4-anti-Markovnikov pathway. Through
the hydrothiolation of an essential oil (β-farnesene),
we achieve the first enantioselective synthesis of (−)-agelasidine
A.