From Propargylic Fluorinations to [1,3]-Rearrangements: Anion and Ligand Effects in Cu-Acetylide Chemistry

Abstract

Metal-catalyzed reactions of propargylic substrates have been widely studied. Of this reaction class, Cu-catalyzed methods have received much attention within the past decade, with Cu-allenylidenes being proposed as key reactive intermediates. This Synpacts article will outline our development of a nucleophilic fluorination protocol of propargylic electrophiles using copper catalysis. Following an analysis of the importance of anion and ligand effects, this study led us to the unexpected discovery of a formal [1,3]-rearrangement of O-propargylic alkoxypyridine derivatives that was later rendered enantioselective. By contrast to Cu-allenylidene proposals, our mechanistic findings have identified alternatives involving bimetallic intermediates.

1 Introduction

2 Propargylic Fluorination

3 Anion Effects

4 Propargylic Rearrangements

5 Mechanistic Studies

6 Conclusions

Key words

copper - catalysis - alkynes - enantioselectivity - alkyne complexes - asymmetric catalysis

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