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Ghosez Keteniminium-Olefin Cyclization

(Ghosez [2+2] Keteniminium-Olefin Cycloaddition)

Published Online: 15 SEP 2010

DOI: 10.1002/9780470638859.conrr269

Comprehensive Organic Name Reactions and Reagents

Comprehensive Organic Name Reactions and Reagents

How to Cite

2010. Ghosez Keteniminium-Olefin Cyclization. Comprehensive Organic Name Reactions and Reagents. 269:1221–1226.

Publication History

  1. Published Online: 15 SEP 2010

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Abstract

This reaction is the synthesis of cyclobutanones from the reaction of alkenes and keteniminium ions. The keteniminium ions are generated from tertiary amides by reacting with triflic anhydride and a hindered pyridine base or by the dechlorination of 1-chloro-N,N,2-trimethyl-1-propylenamine with AgBF4 followed by the hydrolysis of the resulting iminium salts under biphasic conditions. This reaction is known as Ghosez keteniminium-olefin cyclization and 1-chloro-N,N,2-trimethyl-1-propylenamine, generated by the treatment of N,N-dimethyl 2-methylpropionamide with phosgene and triethylamine, is known as the Ghosez reagent. It has been found that the [2+2] cycloaddition between keteniminium and imines to form β-lactams and azetidiniminium salts are generated from this cycloaddition, which can be converted into many different molecules besides β-lactams. It has been reported that the ratio of β-lactams to β-amino amides depends on the relative rate of protonation on the exocyclic and endocyclic nitrogen atom of the tetrahedral intermediate. This reaction has wide applications in heterocycle synthesis but has not yet been extensively explored.

Keywords:

  • N,N-dimethyl 2-methylpropionamide;
  • β-lactams;
  • azetidinimines;
  • ketenes