Highly Regioselective Synthesis of gem-Difluoroallenes through Magnesium Organocuprate SN2‘ Substitution

The reaction of gem-difluoropropargyl electrophiles with Grignard reagents is complicated by the inherent difficulty of executing nucleophilic substitutions on a CF2 group, and the facile formation of carbenoid intermediates arising from α-elimination of fluoride. In the presence of an excess amount...

Full description

Saved in:
Bibliographic Details
Published in:Organic letters 2006-02, Vol.8 (3), p.479-482
Main Authors: Mae, Masayuki, Hong, Jiyoung A, Xu, Bo, Hammond, Gerald B
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The reaction of gem-difluoropropargyl electrophiles with Grignard reagents is complicated by the inherent difficulty of executing nucleophilic substitutions on a CF2 group, and the facile formation of carbenoid intermediates arising from α-elimination of fluoride. In the presence of an excess amount of a copper salt, a Grignard reagent reacts with gem-difluoropropargyl bromide via an SN2‘ mechanism to produce gem-difluoroallene in high yield. If desired, the resulting difluoroallene can undergo a second nucleophilic attack on the CF2 terminus to yield a trisubstituted monofluoroallene through an addition−elimination mechanism.
ISSN:1523-7060
1523-7052
DOI:10.1021/ol052816g