Ozonolyses of indene (1a) and of 1-alkyl- and 1,1-dialkyl-substituted indenes 1b-h in protic solvents including methanol, 2-propanol, and trifluoroethanol revealed that (i) two types of the solvent-derived products, a hemiperacetal and/or an isochroman derivative, are produced depending on the nucleophilicity of the solvent and the steric bulk of the alkyl substituent(s), and (ii) the regiochemistry of the fragmentation of a primary ozonide is a marked function of the nature of the 1-alkyl-substituent. In the case of indene (1a) and 1-substituted indenes 1b-e, both possible modes of primary ozonide cleavage operate competitively yielding two carbonyl oxide intermediates in roughly equal amounts, whereas in the case of 1,1-dialkyl-substituted indenes 1f-h the contribution of the less-hindered carbonyl oxide predominates. © 1995 American Chemical Society.
|Number of pages||9|
|Journal||Journal of Organic Chemistry|
|Publication status||Published - 1995|