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
Synthesis of Caeliferins, Elicitors of Plant Immune Responses: Accessing Lipophilic Natural Products via Cross Metathesis
作者:Inish O’Doherty、Joshua J. Yim、Eric A. Schmelz、Frank C. Schroeder
DOI:10.1021/ol202541b
日期:2011.11.4
A crossmetathesis (CM)-based synthesis of the caeliferins, a family of sulfooxy fatty acids that elicit plant immune responses, is reported. Unexpectedly, detailed NMR spectroscopic and mass spectrometric analyses of CM reaction mixtures revealed extensive isomerization and homologation of starting materials and products. It is shown that the degree of isomerization and homologation in CM strongly
accelerative asymmetricgoldcatalysis is achieved for the first time via chiral ligand metal cooperation. An asymmetrically positioned remote amide group in the designed chiral binaphthyl-based ligand plays the essential role of a general base catalyst and selectively accelerates the cyclizations of 4-allen-1-ols into one prochiral allene face. The reactions are mostly highly enantioselective with achiral
Synthetic Studies toward Phorboxazole A. Stereoselective Synthesis of the C<sub>28</sub>−C<sub>46</sub> Side Chain Fragment
作者:David R. Williams、Michael P. Clark、Ulrich Emde、Martin A. Berliner
DOI:10.1021/ol0063656
日期:2000.9.1
A stereoselectivesynthesis of the C(28)-C(46) fragment (3) of phorboxazole A is described. Key advances include an enantioselective allylation to establish the stereochemistry of the tetrahydropyran unit and a useful SmI(2)-mediated modification of the Barbier reaction of iodomethyloxazole 15 with aldehyde 14.