Efficient and Versatile Stereoselective Synthesis of Cryptophycins
作者:Christian Alexander Mast、Stefan Eißler、Arvydas Stončius、Hans-Georg Stammler、Beate Neumann、Norbert Sewald
DOI:10.1002/chem.200500282
日期:2005.8.5
units A to D which correspond to the respective amino acids and hydroxy acids. A new synthetic route to unit A allows the selective generation of all four stereogenic centres by introducing two of them in a catalytic asymmetricdihydroxylation, followed by substrate-controlled diastereoselective reactions. The diol also serves as the epoxide precursor. This approach provides selective access to stereoisomers
作者:Heinrich Becker、Marcos A. Soler、K. Barry Sharpless
DOI:10.1016/0040-4020(94)01021-q
日期:1995.1
The asymmetricdihydroxylation procedure (AD) is applied to a variety of polyenes. In many cases excellent regioselectivities are obtained. The observed selectivities are rationalized in terms of electronic and/or steric effects inherent to the substrate, superimposed on the substrate's favorable or unfavorable interactions with the binding pocket of the AD ligand. Surprisingly, for medium and large
Remote steric effect on the regioselectivity of Sharpless asymmetric dihydroxylation
作者:Yan Zhang、George A. O'Doherty
DOI:10.1016/j.tet.2005.03.119
日期:2005.6
Studies on the regioselectivities for the Sharpless asymmetric dillydroxylation (AD) of conjugated dienoates, trienoates, dienones and dienamides are described. Excellent regioselectivities were obtained in straight chain dienoates, all trienoates, ketones damicles. The remote branched iso-propyl and tert-butyl groups of dienoates greatly lowered the normally excellent regiocontrol. This observation is rationalized in terms of substrate conformational changes, and the steric interaction between the branched methyl group of iso-propyl ortertbutyl groups and the ethyl group Oil the (DHQD)(2)PHAL ligand. (c) 2005 Elsevier Ltd. All rights reserved.
A Simple and Efficient Total Synthesis of a Styryllactone, 7-<i>epi</i>-Goniodiol
作者:Gowravaram Sabitha、K. Sudhakar、J. Yadav
DOI:10.1055/s-2007-965879
日期:2007.2
Regioselective mono-dihydroxylation, Red-Al reduction, and cis-Horner-Wadsworth-Emmons reactions have been efficiently performed as key steps in the synthesis of 7-epi-goniodiol, isolated from Goniothalamus leiocarpus.