Photoproducts Derived from 9-Substituted Dibenzobarrelenes

Irradiation of 11,12-dibenzoyl-9,10-dihydro-9-hydroxymethyl-9,10-ethenoanthracene, (1a), and 11,12-dibenzoyl-9,10-dihydro-9-methoxy-9,10-ethenoanthracene, (1b), gave the corresponding 4b-substituted dibenzosemibullvalenes, 8c,8d-dibenzoyl-4b-hydroxymethyl-4b,8b,8c,8d-tetrahydrodibenzo[a,f]cyclopropa [cd]pentalene, C₃₁H₂₂O₃, (2a), and 8c,8d-dibenzoyl-4b-methoxy- 4b,8b,8c,8d-tetrahydrodibenzo[a,f]cyclopropa[cd]pentalene, C₃₁H₂₂O₃, (2b), respectively. The molecular structures of (2a) and (2b) have been established unambiguously by single-crystal X-ray diffraction studies.

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