Chiral organoaluminum complex 1 efficiently catalyzed the asymmetric hetero-ene reaction of commercially available 2-methoxypropene (2) with aldehydes under mild conditions to give the corresponding β-hydroxymethyl ketones 3 in good to excellent chemical yields with high enantiomeric excesses. The asymmetriccatalysis of 1 was further applied to the carbonyl addition of methallylsilanes, where exclusive
作者:Gary E. Keck、Yam B. Poudel、Thomas J. Cummins、Arnab Rudra、Jonathan A. Covel
DOI:10.1021/ja110198y
日期:2011.2.2
synthetic route adopted is a highly convergent one in which the preformed, heavily functionalizedpyran rings A and C are united by "pyran annulation", the TMSOTf-promoted reaction between a hydroxyallylsilane appended to the A-ring fragment and an aldehyde contained in the C-ring fragment, with concomitant formation of the B ring. Further elaborations of the resulting very highly functionalized intermediate
苔藓抑素 1 是一种海洋天然产物,是一种非常有前景的先导化合物,因为它对多种人类疾病状态显示出强大的生物活性。我们在此描述了该试剂的首次全合成。所采用的合成路线是一种高度收敛的路线,其中预先形成的、高度官能化的吡喃环 A 和 C 通过“吡喃环化”结合,即附加在 A 环片段上的羟基烯丙基硅烷与包含在 A 环片段中的醛之间的 TMSOTf 促进反应。 C 环片段,伴随 B 环的形成。所得的高度官能化中间体的进一步加工包括大环内酯化和仅存在的五个酯键之一的选择性裂解。
Enantioselective Synthesis of
<i>cis</i>
‐2,
<scp>6‐Disubstituted</scp>
‐4‐methylene Tetrahydropyrans via Chromium Catalysis
<sup>†</sup>
作者:Jing Bai、Bin Chen、Guozhu Zhang
DOI:10.1002/cjoc.202000296
日期:2020.12
2‐(trimethylsilyl methyl)allylation and Prins cyclization. Commercially available (2‐(chloromethyl)allyl)trimethylsilane serves as the bifunctional linchpin to combine two aldehydes to assemble the 2,6‐disubstituted pyrans. A variety of functional groups are compatible under the mild reaction conditions. The synthetic utility of this methodology was demonstrated by the asymmetricsynthesis of 16 examples of
A Bidirectional S<sub>E</sub>′ Strategy for 1,5-<i>syn</i> and 1,5-<i>anti</i> Stereocontrol toward the Synthesis of Complex Polyols
作者:David R. Williams、Christopher D. Claeboe、Bo Liang、Nicolas Zorn、Nicholas S. C. Chow
DOI:10.1021/ol3015682
日期:2012.8.3
Studies report a bidirectional SE′ strategy applicable for the stereocontrolled synthesis of nonracemic 1,5-syn and 1,5-anti diols and their derivatives. Nonracemic 1,3,2-diazaborolidine auxiliaries are incorporated by chemoselective tin–boron exchange to provide reactive allylic boranes. The convergent pathway utilizes sequential reactions with two aldehydes producing stereochemical outcomes from
研究报告了一种双向 S E ' 策略,适用于非外消旋 1,5- syn和 1,5- anti二醇及其衍生物的立体控制合成。非外消旋 1,3,2-二氮杂硼烷助剂通过化学选择性锡-硼交换加入,以提供反应性烯丙基硼烷。收敛途径利用与两种醛的顺序反应,分别从循环、闭合和开放过渡态偏好产生立体化学结果。peloruside A片段16的合成分四步完成,由容易获得的醛9和13 组成。