Construction of the [6,5,7,5] Tetracyclic Core of Calyciphylline A Type Alkaloids via a Tandem Semipinacol Rearrangement/Nicholas Reaction
作者:Hui Shao、Wen Bao、Ze-Ran Jing、Yun-Peng Wang、Fu-Min Zhang、Shao-Hua Wang、Yong-Qiang Tu
DOI:10.1021/acs.orglett.7b02274
日期:2017.9.1
A novel and efficient approach toward the assembly of the synthetically challenging tetracyclic [6,5,7,5] core structure of calyciphylline A-type alkaloids is developed. The synthetic route features a tandem semipinacol rearrangement/Nicholas reaction that has been devised strategically to construct the spirocyclic A/Bring and the sterically congested vicinal all-carbon quaternary carbon centers in
Reaction of Alkynyl- and Alkenyltrifluoroborates with Propargyldicobalt Cations: Alkynylation, Alkenylation, and Cyclopropanation Product Pathways
作者:Brent St Onge、S. Maryamdokht Taimoory、Jeffrey Battersby、John F. Trant、James R. Green
DOI:10.1021/acs.joc.1c02352
日期:2021.12.17
alkenyltrifluorobrates directly alkenylate, predominantly with the retention of stereochemistry. C-1-substituted alkenyltrifluoroborates alkenylate at C-2. Potassium vinyltrifluoroborate incorporates a cyclopropane at the site propargyl to alkynedicobalt. Computational analysis of these systems explains the differential modes of reactivity of alkenyltrifluoroborates and outlines the probable mechanisms for