Synthesis of Azocine Derivatives from Thioaldehyde Diels-Alder Adducts

Article abstract of DOI:10.1021/jo00245a019

Nitrogen-containing phenacyl sulfides 1 or 2 can be readily cleaved to thioaldehydes that are trapped by electron-rich dienes to give the adducts 4, 5, 11, or 17.The adducts have electrophilic character α to sulfur and can be converted into structures having new C-N bonds at the α-carbon.Thus, 4 leads to lactam 6 by S to N acyl transfer.A similar reaction occurs from 15 to the eight-membered 16.Internal addition of amine nitrogen to Danishefsky diene adducts 11, 17, or 26 affords bicyclic aminals which are converted into azocine derivatives upon desulfurization.Stable structures such as 24, 25, and 31 are prepared in this way.The unusual enaminone 20 is not stable and rearranges upon attempted purification to 21.