Intramolecular electrophilic cyclization of functional derivatives of unsaturated compounds: II. Synthesis and transformation of N-{(2Z)-5-[(arylsulfanyl)methyl]dihydrofuran-2(3H)-ylidene}-N-alkyl(aryl)aminium perchlorates

Abstract

N-Alkyl(aryl)amides of allylacetic acid when reacting with arylsulfenyl chlorides in acetic acid in the presence of lithium perchlorate undergo a selective cyclization to form N-{(2Z)-5-[(arylsulfanyl)methyl] dihydrofuran-2(3H)-ylidene}-N-alkyl-(aryl)aminium perchlorates. Treating of the latter with sodium acetate leads to the formation of the corresponding 5-[(arylsulfanyl)methyl]lactones, and with sodium ethylate, to 5-[(arylsulfanyl) methyl]-2-iminolactones. In reaction with secondary cycloalkylamines in the presence of water a transamidation and tetrahydrofuran ring opening occurs to afford 5-arylsulfanyl-4-hydroxypentanoic acid amides.