Reactions of 9-substituted 9-thia-10-azaphenanthrenes with electrophiles

Abstract

Reactions of 9-substituted 9-thia-10-azaphenanthrenes with several electrophiles have been investigated. Reaction of 9-alkyl-9-thia-10-azaphenanthrenes with dimethyl acetylenedicarboxylate (DMAD) afforded dibenzothiazonine derivatives 4 and 5, dibenzothiazocine derivatives 6, 2-alkylsulfinyl-2′-vinylaminobiphenyls 7, and bis(biphenylylimino)ethane derivatives 8. The product distribution was markedly influenced by the substituent on the sulfur atom. 9-Methyl 3a and 9-isopropyl derivatives 3d afforded predominantly dibenzothiazonine derivatives 5a and 4d, respectively, while 9-ethyl 3b, 9-isopropyl 3c and 9-cyclohexyl derivatives 3e gave predominantly dibenzothiazocine derivatives 6 and alkylsulfinyl vinylaminobiphenyls 7. In contrast, the reactions of 9-phenyl-3f or 9-vinyl-9-thia-10-azaphenanthrene 3g with DMAD afforded only the corresponding dibenzothiazocine derivative 6. Reactions of 9-alkylthiaazaphenanthrenes 3a–c with methyl propiolate (MP) in benzene afforded dibenzothiazecine derivatives 12 as 1:2 adducts. Reactions of compounds 3a–c with diphenylcyclopropenone in ethanol yielded the ring-opened products 13, while the same reaction in benzene solvent afforded the 4-quinolone derivatives 14via intramolecular cyclization of a ketene intermediate, L.