ChemInform Abstract: New Synthesis of Multi‐Substituted α‐Chlorocyclobutanones from 1‐Chloro‐3‐cyanoalkyl p‐Tolyl Sulfoxides by 4‐exo‐dig Nucleophilic Ring Closure of Magnesium Carbenoids to Nitrile Group as the Key Reaction.

Abstract

1-Chloro-3-cyanoalkyl p-tolyl sulfoxides were easily prepared from 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from carbonyl compounds and chloromethyl p-tolyl sulfoxide, with lithium α-cyano carbanion of acetonitrile derivatives in good yields. Treatment of these sulfoxides with i-PrMgCl resulted in the formation of multi-substituted α-chlorocyclobutanones in good to high yields via the 4-Exo-Dig nucleophilic ring closure of the generated magnesium carbenoid intermediates to the nitrile group. This procedure provides a new and good way for the synthesis of multi-substituted α-chlorocyclobutanones from carbonyl compounds and substituted acetonitriles with formation of three carbon–carbon bonds in relatively short steps.