Highly Stereoselective Synthesis of <i>anti</i>,<i>anti</i>-Dipropionate Stereotriads: A Solution to the Long-Standing Problem of Challenging Mismatched Double Asymmetric Crotylboration Reactions
作者:Ming Chen、William R. Roush
DOI:10.1021/ja300472a
日期:2012.2.29
aldehydes with the chiral, nonracemic crotylborane reagent (S)-(E)-22 (or its enantiomer). This method not only provides direct access to anti,anti-dipropionate stereotriads 24 [a synthetic equivalent of 4] with very good (5-8:1) if not excellent (≥15:1) diastereoselectivity from β-branched chiral aldehydes with ≤50:1 intrinsic diastereofacial selectivity preferences but also provides a vinylstannane
Epoxyamide-Based Strategy for the Synthesis of Polypropionate-Type Frameworks
作者:Francisco Sarabia、Francisca Martín-Gálvez、Miguel García-Castro、Samy Chammaa、Antonio Sánchez-Ruiz、José F. Tejón-Blanco
DOI:10.1021/jo801728s
日期:2008.11.21
A new approach to the stereoselectivesynthesis of polypropionate-type frameworks is reported utilizing reactions of amide-stabilized sulfur ylides with chiral aldehydes. To establish a new strategy for macrolide fragmentsynthesis, the stereoselectivity of these reactions in the construction of epoxy amides was the most important aspect of this study. In this aspect, we found a strong influence of
Sparteine free Hoppe–Matteson–Aggarwal rearrangement was applied to various chiral acetonides. Utilizing different vinyl boronic esters a high level of substrate control was observed leading to excellent selectivities. These selectivities were attributed to stereoelectronic effects of the neighboring acetonide moiety. The obtained formal Felkin and anti-Felkin products feature up to four contiguous
The synthesis of the polypropionate chain of Streptovaricin U (1) is described utilizing a new approach for the stereoselective synthesis of the macrolide-type antibiotics via sulfur ylides.