Beilstein J. Org. Chem.2010,6, No. 37, doi:10.3762/bjoc.6.37
, Shanghai 200032, China 10.3762/bjoc.6.37 Abstract The straightforward synthesis of four gem-difluoromethylenated analogues 4–7 of boronolide is described. The key steps of the synthesis include the concise preparation of the key intermediates 12a–b through the indium-mediated gem-difluoropropargylation of
aldehyde 9 with the fluorine-containing building block 11 and the efficient construction of α,β-unsaturated-δ-lactones 15a–b via BAIB/TEMPO-procedure.
Keywords: boronolide; gem-difluoromethylenated analogues; gem-difluoropropargylation; α,β-unsaturated-δ-lactones; Introduction
(+)-Boronolide (1
from Tetradenia riparia [3][5], a Central African species traditionally employed by the Zulu as an emetic, and whose leaf infusions have also been reported to be effective against malaria [2][4]. Boronolide (1) and its analogues 2–3 feature an interesting polyacetoxylated (or polyhydroxyl) side chain