A facile synthesis of 5-methyl-6,8-dioxabicyclo[3.2.1]octan-3-ones from 4-(t-butyldimethylsiloxy)pent-3-en-2-one and protected α-ketols. A synthesis of (±)-frontalin
Abstract
An efficient method for the synthesis of substituted 5-methyl-6,8-dioxabicyclo[3.2.1]octan-3-one derivatives (4a–f) and (6) has been developed. This utilises the cross-aldol condensation of the lithium enolate of 4-(t-butyldimethylsiloxy)pent-3-en-2-one (1) with the protected α-ketols (2a–g) and (5) and subsequent acid-catalysed deprotection and intramolecular acetalisation. A short synthesis of (±)-frontalin (14) was carried out using this method.