7-1(1-Acetoxymethylidene) Bensonorbornadiene: A versatile re-agent for the synthesis of 7-formyl and 7-hydroxymethyl benzonorbornadienes

7-(1-Acetoxymethylidene)benzonorbornadiene 3, prepared in one step by the addition of benzyne to 6-acetoxyfulvene 2, is hydrolysed in acid solution to form a 3:2-epimeric mixture of syn- and anti- 7-formylbenzonorbornadienes 4 and 5, respectively; the corresponding 7-hydroxymethylbenzonorbornadienes 6 and 9 were produced by reduction of the formyl isomers with sodium borohydride.