hetero-Michael (DIHMA) reaction to alkynones was applied. The sequence allows for introduction of numerous substituents on the scaffold and for variation of stereochemistry. [5.5]-Spiroketals bearing an additional ketone were obtained in high overall yields. Further diversification was achieved by reduction of the ketone and reductive amination using polymer-supported borohydride, Grignard reaction and conversion
Highly (<i>E</i>)-Selective BF<sub>3</sub>·Et<sub>2</sub>O-Promoted Allylboration of Chiral Nonracemic α-Substituted Allylboronates and Analysis of the Origin of Stereocontrol
作者:Ming Chen、William R. Roush
DOI:10.1021/ol1007444
日期:2010.6.18
delta-Methyl-substituted homoallylic alcohols 2 were prepared in 71-88% yield, E:Z>30:1 and 93% to >95% ee via BF3 center dot Et2O-promoted allylboration with alpha-Me-allylboronate 1. The origin of high (E)-selectivity is proposed.
A Formal Synthesis of Herboxidiene/GEX1A
作者:Jhillu S. Yadav、G. Madhusudhan Reddy、S. Rehana Anjum、B. V. Subba Reddy
DOI:10.1002/ejoc.201402235
日期:2014.7
A formalsynthesis of herboxidiene/GEX 1A is described. This approach demonstrates successful application of the Prins cyclization for the construction of the tetrahydropyran core of the target molecule. The chirality of the side chain has been established through the Sharpless asymmetric dihydroxylation and Evan's alkylation. The olefin cross-metathesis was applied to couple both key fragments.