A Pummerer-Type Novel Ring Fission of 2-Methylsulfinyl-5,6-dihydro-4H-1,3,4-thiadiazine Derivatives: A Homologation of Aldehydes and Ketones

Article abstract of DOI:10.1246/bcsj.69.1043

Aldehydes and ketones were converted into 2-methylsulfinyl-5,6-dihydro-4H-1,3,4-thiadiazines via the formation and base-induced ring-closure of N-alkylidene-N′-bis(alkylthio)methylenehydrazines followed by mCPBA oxidation. The subsequent Pummerer-type ring fission of the rings was performed by treating with trifluoroacetic anhydride or trifluoromethanesulfonic anhydride at -78°C to give α,β-unsaturated esters and ketones in modest yields. Thus, this reaction sequence was regarded as being a new method for the two-carbon homologation of aldehydes and ketones.