Short Synthesis of (+)-Aspicilin via Asymmetric Hexahydroxylation of a Triene
摘要:
Asymmetric synthesis of the 18-membered lichen macrolide (+)-aspicilin has been achieved in 14 steps and 11% overall yield, starting from an achiral hydrocarbon, (3E)-hexadeca-1,3,15-triene. All four stereogenic carbinol centers have been introduced by three Sharpless asymmetric dihydroxylation (AD) reactions, using both AD-mix-beta and AD-mix-alpha to produce the hexol with very high regio- and enantioselectivity (epimeric excess of 88% at position 2, 96% at positions 3 and 4, and 86% at position 15).
Karatungiols A (1) and B (2), two novel antimicrobial polyol compounds, were isolated from the cultivated symbiotic marinedinoflagellateAmphidiniumsp. Their structures were elucidated based on spectroscopic analysis and degradation reactions. Karatungiols A (1) and B (2) consisted of a C69-linear chain with a ketone moiety, 24 or 25 hydroxyl groups, and two tetrahydropyran rings. Karatungiol A (1)