Preparation of alkylidenecyclobutanes and their transformation to 2,2-disubstituted cyclopentanones

摘要

The reaction of ketones with the titanocene reagent prepared by the treatment of 1,1-bis(phenylthio)cyclobutane with the low valent titanium species Cp2Ti[P(OEt)(3)](2) produced the corresponding alkylidenecyclobutanes. These compounds were successfully transformed into 2,2-disubstituted cyclopentanones by the epoxidation and subsequent ring enlargement. The similar reactions of the carbene complexes with carboxylic esters and thiolesters also proceeded to afford (1-alkoxy- and alkylthio-alkylidene)cyclobutanes, respectively, in good yields. [References: 11]