Variations of solvent and substitution pattern in Pb(OAc)4 mediated domino reactions

Abstract

The effect of solvent on oxidative cleavage of the Hajos–Parrish ketone derived hydrindene–diols 1, and Wieland–Miescher ketone derived octaline–diols 2 with Pb(OAc)4 is presented. Various solvents were screened and compared for these domino reactions. Changing the solvent influenced the reaction rate, product distribution, and chemical yield in the octalin–diol series, while no-effect was detected in the lower homologue hydrindene–diol series. The use of a cheap, readily available chiral carboxylic acid, such as (S)-2-acetoxypropionic acid gave diastereomeric mixtures when performed in the racemic series, offering the potential of a chemical resolution. The influence of the substitution pattern on the substrate was also investigated on variously substituted derivatives of 1. Diols 38 failed to give any detectable amount of IMDA type ring closure, leading only to dialdehyde 39. For the compounds studied, alkyl or carboxyalkyl substituents on the olefin 41 and 44 led to incomplete cascade transformation due to steric interference caused by the alkyl or acyl groups. The oxidative cleavage of unsaturated diols 46 and 48 derived from monocyclic precursors, used as templates to determine whether any unsaturated 1,2-diol could be regarded as a substrate, is also described.