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SYNTHESIS OF SYMMETRICAL CHROMENO[2,3-b]CHROMENES ON THE BASIS OF О-QUINONE METHIDES AND 1,1-BIS(MORPHOLINO)ETHENE
Abstract
The reaction of 1,1-bis(morpholino)ethene with precursors of о-quinone methides derived from Mannich bases of phenols and
2-naphthols provided a series of chromeno[2,3-b]chromenes. The cascade process included a hetero-Diels–Alder reaction between
о-quinone methide and ketenaminal, elimination of secondary amine, and [4+2] cycloaddition between о-quinone methide and the
chromene intermediate.
2-naphthols provided a series of chromeno[2,3-b]chromenes. The cascade process included a hetero-Diels–Alder reaction between
о-quinone methide and ketenaminal, elimination of secondary amine, and [4+2] cycloaddition between о-quinone methide and the
chromene intermediate.
Keywords
chromeno[2,3-b]chromenes, ketenaminals, о-quinone methides, cascade reactions, Diels–Alder reaction.
Latvian Institute of Organic Synthesis - Aizkraukles iela, 21, Riga, LV-1006, Latvia - hgs@osi.lv