Synthesis of gem-difluoromethylenated analogues of boronolide

• Jing Lin,
• Xiao-Long Qiu and
• Feng-Ling Qing

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

• ]. Considering the similarity in size of fluorine and hydrogen atoms, the strong electron-withdrawing property of gem-difluoromethylene group (CF2) [19][20] and our continual efforts to prepare gem-difluoromethylenated analogues of natural products containing α,β-unsaturated-δ-lactone moiety [21][22][23][24], we