Reductive anti‐Dizincation of Arylacetylenes

Abstract

Arylacetylenes undergo anti‐1,2‐dizincation to afford trans‐1,2‐dizincioalkenes. The process employs sodium dispersion as a reducing agent and zinc chloride TMEDA complex as a reduction‐resistant zinc electrophile. This reductive anti‐dizincation contrasts with the conventional additive syn‐dimetalation like silylzincation. The resulting dizincated alkenes undergo the cross‐coupling to yield multi‐substituted alkenes stereoselectively.

Sodium-Mediated Reductive anti-Dimagnesiation of Diarylacetyl­enes with Magnesium Bromide

“…13 All the resonances in the 1 H and 13 C NMR spectra of (E)-10 were consistent with the reported values. 10 The rest of the 1 H NMR resonances of (Z)-10 could not be assigned due to overlapping with the resonances of (E)-10.…”

“…Very recently, we have achieved reductive antidizincation of alkynes using ZnCl 2 (tmeda) as a reductionresistant zinc electrophile (Scheme 1E). 10 Encouraged by the success of the dizincation using a simple zinc halide, we decided to revisit the investigation of magnesiation reagents, despite the intuition that simple magnesium halides readily undergo reduction by sodium metal to form Rieke Scheme 1 Generation of organomagnesium species: A) Common methods for generation of organomagnesium halides. B) -Elimination from 1-magnesio-2-halo species.…”