Transannular reactions in the dibenzo[a,d]cycloheptene series. II. Preparation of 10,11-dihydro-10,5-(epoxymethano)-5H-dibenzo [a,d] cyclohepten-13-one and derivatives

The reaction of electrophilic reagents with the 5-substituted 5H-dibenzo[a,d]cycloheptene derivatives (13a–e) and with their 10,11-dihydro analogues (19a–b) occurs with transannular participation of the 5-substituent to yield derivatives of 10,11-dihydro-10,5-(epoxymethano)-5H-dibenzo[a,d]cycloheptene. The epimeric 10,11-dihydro-10-hydroxy-5H-dibenzo[a,d]cycloheptene-5-carboxamides (22, 23) are described. The syn-hydroxy isomer 22 is readily transformed to the lactone 16c under neutral conditions whereas the anti isomer 23 requires acid catalysis for this conversion. Treatment of anti-11-bromo-10,11-dihydro-10,5-(epoxymethano)-5H-dibenzo[a,d]cyclohepten-13-one (16b) with ammonia or primary aliphatic amines gives the epoxyamides 21a–d which can react with secondary aliphatic amines to give the anti-11-dialkylamino-10,11-dihydro-10,5-(epoxymethano)-5H-dibenzo[a,d]cyclohepten-13-ones (25a–d). The epimeric syn-11-dialkylamino compounds 24a–e are obtained from the interaction of 16b with secondary aliphatic amines. The nuclear magnetic resonance spectra of the products are tabulated.