Second-Generation DBFOX Ligands for the Synthesis of β-Substituted α-Amino Acids via Enantioselective Radical Conjugate Additions

被引：23

作者：

Banerjee, Biplab ^{[1
]}

Capps, Steven G. ^{[1
]}

Kang, Junghoon ^{[1
]}

Robinson, Joshua W. ^{[1
]}

Castle, Steven L. ^{[1
]}

机构：

[1] Brigham Young Univ, Dept Chem & Biochem, Provo, UT 84602 USA

来源：

JOURNAL OF ORGANIC CHEMISTRY | 2008年 / 73卷 / 22期

基金：

美国国家卫生研究院;

关键词：

D O I：

10.1021/jo801721z

中图分类号：

O62 [有机化学];

学科分类号：

070303 [有机化学]; 081704 [应用化学];

摘要：

A set of second-generation DBFOX ligands possessing extended aryl or benzyl-type groups was synthesized. The requisite amino alcohols were either commercially available (DBFOX/Bn) or constructed via Sharpless asymmetric aminohydroxylation (DBFOX/Nap, DBFOX/t-BuPh, DBFOX/Pip) or phase-transfer-catalyzed asymmetric alkylation (DBFOX/MeNap). Complexes of the ligands with Mg(NTf2)(2) were evaluated as promoters of enantioselective radical conjugate additions to alpha,beta-unsaturated alpha-nitro amides and esters. Reactions employing the DBFOX/Nap ligand exhibited improved enantioselectivity relative to previously published additions mediated by DBFOX/Ph. However, the relatively modest increase in diastereomeric ratio suggests that our substrate-Lewis acid binding model, which was formulated based on results from DBFOX/Ph-promoted radical conjugate additions, is in need of revision.

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收藏

页码：8973 / 8978

页数：6

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