C 2对称的双(氮丙啶)配体1-5已通过对亚胺类有机锂试剂的对映选择性加成而得到筛选。发现配体1(以化学计量的量使用)在化学产率和对映选择性方面是优异的,最好的结果是在亚胺6a中添加乙烯基锂后,产率为90%,ee为89%。配体1的用途低于化学计量的量给出较差的收率和较低的对映选择性。研究了反应的对映选择性与底物,试剂,化学计量和温度的函数关系,但尚不能得出确切的机械结论。氘标记的甲基锂的初步结果表明涉及配体,试剂和底物的络合/交换过程。
Modular Asymmetric Synthesis of 1,2-Diols by Single-Pot Allene Diboration/Hydroboration/Cross-Coupling
作者:Nicholas F. Pelz、James P. Morken
DOI:10.1021/ol0616891
日期:2006.9.1
Chiral allyl vinyl boronates are generated by catalytic enantioselective diboration of prochiral allenes. They may then be reacted, in situ, with a hydroborating reagent to form a novel triboron intermediate. The least hindered and most reactive C-B bond then participates in cross-coupling wherein the coupling is brought about by the same catalyst as that which catalyzed the diboration reaction. The
Synthesis and Reactivity of Enantiomerically Enriched Thiiranium Ions
作者:Scott E. Denmark、Thomas Vogler
DOI:10.1002/chem.200901377
日期:2009.11.2
Enantiomericallyenrichedthiiraniumion 5 has been prepared by silver‐assisted ionization of chloro sulfide 4 at −20 °C. This thiiraniumion is configurationally stable in solution up to room temperature as demonstrated by the stereospecific capture of the ion by various oxygen‐ and nitrogen‐based nucleophiles. Both isolated olefins and weak Lewis bases can promote the racemization of 5 but these
Enantioselective Acyloin Rearrangement of Acyclic Aldehydes Catalyzed by Chiral Oxazaborolidinium Ion
作者:Soo Min Cho、Si Yeon Lee、Do Hyun Ryu
DOI:10.1021/acs.orglett.1c00314
日期:2021.2.19
A catalytic enantioselective acyloin rearrangement of acyclic aldehydes to synthesize highly optically active acyloin derivatives is described. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provided chiral α-hydroxy aryl ketones in high yield (up to 95%) and enantioselectivity (up to 98% ee). In addition, the enantioselective acyloin rearrangement of α,α-dialkyl-α-siloxy
The attempted stereoselective synthesis of chiral 2,2′-biindoline
作者:Mary J. Gresser、Steven M. Wales、Paul A. Keller
DOI:10.1016/j.tet.2010.06.035
日期:2010.8
The attempted first stereoselective synthesis of 2,2'-biindoline using a metathesis-Sharpless asymmetric dihydroxylation strategy results in the synthesis of the heterocycle in poor to modest stereoselectivity. Attempts to improve the ee by varying the heteroatom protecting groups in key intermediates did not enhance the outcome of the Sharpless AD reaction. Therefore a limitation of this AD reaction is the use of 1,4-substituted but-2-enes where these substituents are ortho-substituted aromatics. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Wallace, Timothy W.; Wardell, Ian; Li, Ke-Dong, Journal of the Chemical Society. Perkin transactions I, 1995, # 18, p. 2293 - 2308
作者:Wallace, Timothy W.、Wardell, Ian、Li, Ke-Dong、Leeming, Peter、Redhouse, Alan D.、Challand, S. Richard