Intramolecular reactivity of 1-alkoxyanthronylidenes. Disproportionation (set) of carbene-derived 1,5-biradicals

Article abstract of DOI:10.1016/S0040-4039(98)01398-7

Photolyses of 1-alkoxy-9-diazoanthrones 12 in benzene induce abstraction of hydrogen from the side chain, followed by cyclization (→ 15 → 16) or disproportionation (→ 17 + 18) of the intervening biradicals 20. In alcohols, reduction of triplet anthronylidenes (³14 → 21 → 22) competes with the formation of 20, and intramolecular electron transfer of 20 leads eventually to the acetals 24.