1,7-electrocyclisations of 4-azaheptatrienyl lithium compounds to 4,5-dihydroazepines

Klötgen S, Würthwein EU

Abstract

Deprotonation of 4-aza-1,3,6-heptatrienes 9, 10 at -78°C using lithium diisopropylamide as base yields 4-azaheptatrienyl lithium compounds 11. During warming up to room temperature (to 40°C for 10) they undergo a 1,7-electrocyclisation to afford 3-azacycloheptadienyl lithium compounds 13. Subsequent treatment with various electrophiles provides access to several substituted 4,5-dihydroazepines 14.