Synthesis of a Novel Non-Benzenoid Quinone, 3,10-Dihydro-2,4-dimethyl-7,13-methanocyclohepta[11]annulene-3,10-dione, from 8H-7,9-Bis(methoxycarbonyl)-5,11-methano[11]annuleno[c]furan-8-one
摘要:
8H-7,9-Bis(methoxycarbonyl)-5,11-methano[11]anuleno[c]furan-8-one (3) undergoes [4+3] cycloaddition with an oxyallyl species generated from 2,4-dibromo-3-pentanone in the presence of KI and copper, followed by dehydration in fluorosulfuric acid to give cyclohepta[11]annulenedione diester 9. After hydrolysis of the ester groups, decarboxylation yielded the title quinone 6. The H-1 NMR spectrum of 6 in D2SO4 indicates generation of its protonated dicationic species.