Ketenimine Complexes from Carbene Complexes and Isocyanides: Versatile Building Blocks for Carbocycles and N‐Heterocycles [New Synthetic Methods (74)]

Abstract

Dedicated to Professor Ernst Otto Fischer on the occasion of his 70th birthdayKetenimine complexes are readily available in great variety by reaction of isocyanides with carbene complexes. They have proven to be useful building blocks in new synthetic approaches to carbocyclic and N-heterocyclic four-, five-, and six-membered rings. The reactions involve new metal-induced bond formation patterns of the ketenimine ligands, which can be influenced across a wide range by varying the following five parameters: the metal, the ligands, and the three substituents on the N=C=C unit.

Four-membered rings from isocyanides: Developments since the mid 1980s

“…49 Preparatively, these species have turned out to be valuable building blocks for a variety of four-, five-, and six-membered rings (for reviews, see refs. 50,51 ). Concentrating on the first mentioned class, this section will describe applications of the synthetic principles outlined below.…”

Hexacarbonyls and Carbonyl Complexes of Carbon σ-Bonded Ligands of Chromium, Molybdenum and Tungsten

“…The use of carbene complexes for the synthesis of ketenimine complexes has been reviewed. 557 A characteristic reaction of carbenes of the type [M{=C(NR 1 R 2 )CHR 3 R 4 }(CO) 5 ] is their tendency to deprotonate at the a-carbon position. The resulting anion is reactive towards electrophiles.…”

A three-component synthesis of functionalized ketenimines by the reaction of alkyl isocyanides and dialkyl acetylenedicarboxylates in the presence of 2-quinolinol

“…1 There has been intense interest in their reactions, such as cycloaddition, 2 nucleophilic 3,4 and electrophilic addition. 5 They have also found widespread use as reactive starting materials for the formation of four-, five-, and six-membered heterocyclic ring systems. [5][6][7] Methods for the synthesis of ketenimines have been extensively reviewed.…”

“…5 They have also found widespread use as reactive starting materials for the formation of four-, five-, and six-membered heterocyclic ring systems. [5][6][7] Methods for the synthesis of ketenimines have been extensively reviewed. 8 The addition of nucleophilic carbenes, such as isocyanides, to dialkyl acetylenedicarboxylates was investigated in detail.…”