Total Synthesis and Structural Reassignment of Laingolide A
作者:Fusong Wu、Tao Zhang、Jie Yu、Yian Guo、Tao Ye
DOI:10.3390/md19050247
日期:——
The asymmetric totalsynthesis of four diastereomers of laingolide A was achieved, which led to the unambiguous assignment of the stereochemistry of the natural product. The salient features of the convergent, fully stereocontrolled approach were a copper-catalysed stereospecific Kumada-type coupling, a Julia-Kocienski olefination and an RCM/alkene migration sequence to access the desired macrocyclic
Solvent-Dependent Diastereoselectivities in Reductions of β-Hydroxyketones by SmI<sub>2</sub>
作者:Pramod R. Chopade、Todd A. Davis、Edamana Prasad、Robert A. Flowers
DOI:10.1021/ol049129u
日期:2004.8.1
The reductions of a series of beta-hydroxyketones by Sml(2) were examined in THF, DME, and CH3CN using methanol as a proton source. Reductions in THF and DME typically lead to the syn diastereomer with DME providing higher diastereoselectivities. Reductions in CH3CN provided the anti diastereomer predominantly. This study reveals that solvation plays an important role in substrate reduction by Sml(2).
Reduction of β-Hydroxyketones by SmI<sub>2</sub>/H<sub>2</sub>O/Et<sub>3</sub>N
作者:Todd A. Davis、Pramod R. Chopade、Göran Hilmersson、Robert A. Flowers
DOI:10.1021/ol047835p
日期:2005.1.1
Reduction of a series of beta-hydroxyketones by SmI2/H2O/Et3N provided 1,3-diols in quantitative yields. The reactions were exceedingly clean with no byproduct formation, negating the need for further purification. Most reactions provided moderate to excellent diastereoselectivity with syn-diols as the major isomer in most instances.
Regioselective Ring Opening of Di-isopropylsilylenes Derived from 1,3-Diols with Alkyl Lithium Reagents
作者:Katelyn M. Chando、Patricia A. Bailey、Joseph A. Abramite、Tarek Sammakia
DOI:10.1021/acs.orglett.5b02529
日期:2015.11.6
The selective alkyl lithium-induced ring opening of 1,3-di-isopropylsilylenes is described. The reaction affords a differentially substituted 1,3-diol bearing a silane that resides at the oxygen in the more sterically demanding position. The reaction can be highly selective with a regiochemical preference up to >50:1 and likely proceeds via an alkoxy-silane intermediate. This intermediate can by trapped by methyl iodide to provide the corresponding silyl methyl ether, wherein the silane again resides at the oxygen in the more sterically demanding position.