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Nicholas Reaction

Published Online: 15 SEP 2010

DOI: 10.1002/9780470638859.conrr461

Comprehensive Organic Name Reactions and Reagents

Comprehensive Organic Name Reactions and Reagents

How to Cite

2010. Nicholas Reaction. Comprehensive Organic Name Reactions and Reagents. 461:2049–2053.

Publication History

  1. Published Online: 15 SEP 2010

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Abstract

The nucleophilic substitution on a propargylic alcohol, ether or ester by a carbon or heteroatom nucleophile involving the generation of a carbocation by a strong Lewis acid, stabilization of the propargylic cation via the formation of hexacarbonyldicobalt alkyne complex, and final liberation of alkyne moiety by oxidation with cerium ammonium nitrate or N-methylmorpholine N-oxide is generally referred to as the Nicholas reaction. The Lewis acid BF3 OEt2 is the most commonly used acid for this reaction. All the favorable conditions and mechanism of the reaction have been discussed. It has been found that the application of an Evans's oxazoline enolate in coupling with a propargylic cation generates high stereoselectivity. This reaction has been used for the preparation of cyclic ethers and macrocycles.

Keywords:

  • hexacarbonyldicobalt alkyne complex;
  • cobalt-mediated cyclization;
  • propargylic cation;
  • N-methylmorpholine