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A new synthetic route to benzannelated bisdehydroannulenes is described, which led to the bisdehydrobenz[14]annulenes 14 and 2, the bisdehydrobenz[16]annulenes 25 and 26, and the bisdehydrobenz[18]annulenes 35 and 36, as well as the bisdehydrobenz[20]annulene 41. The electronic and NMR spectra of the various benzannelated bisdehydroannulenes are discussed.

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Recent investigations have shown that direct bromination of (+)-3,3-dibromocamphor provides a mixture of (+) -3,3,8-tribromocamphor, 1,7-dibromo-3,3.4-trimethylnorbornan-2-one, and 1.7-dibromo-4-dibromornethyl-3.3-dimethylnorbornan-2-one. Related studies have shown that (+) -3,9,9-tribromocamphor is a minor product in the known conversion of (+)-3-bromocamphor into (+)-3,9-dibromocarnphor. The for mation of these products can be rationalised by a general mechanistic scheme which also includes mechanisms for the conversion of (+)-camphor into partially racemic 9-bromocamphor, the acid-catalysed racemisation of camphor, and the isomerisation of (+) -3,9-to (-) -6.9-dibromocamphor.

Chemical oxidation of (−)-bornyl acetate provides a mixture of 3-, 5-, and 6-oxobornyl acetate, whereas microbiological hydroxylation with cultures of Helminthosporiumsativum gives a mixture of 2,3-, 2,6-, and 2,5-bornanediols. In each case the reaction occurs preferentially at the C(5) position. Microbiological hydroxylation of (+)-bornyl acetate with H. sativum occurs almost exclusively at the C(5) position. Regiospecific hydroxylation of (+)- or (−)-bornyl acetate with cultures of Fusariumculmorum also occurs at the C(5) position but without concomitant hydrolysis of the acetoxy group.