Allylstannation of N-acyliminium intermediates: a possible method for the stereocontrolled synthesis of polyhydroxypiperidines
摘要:
The stereochemistry of the allylstannation of acyliminium intermediates has been examined for gamma-alkoxyallyltins and gamma-silyloxyallyltributyltins. In the latter case, the reaction has been shown to afford cleanly the syn adduct. Its subsequent ring-closing metathesis and dihydroxylation has allowed the highly stereoselective preparation of a 2-aryl-trihydroxypiperidine. (C) 2003 Elsevier Ltd. All rights reserved.
在三氟化硼的存在下,通过烷基氰基戊酸酯与3,3-二苄氧基-1-三丁基锡烷基丙-1-烯的S N 2'反应,以50-80%的产率获得苄氧基烯丙基三丁基锡。他们在不同的路易斯酸存在下与亚环己基甘油醛反应,并通过与真实的醛糖苷酶比较,在臭氧分解/脱保护序列后明确鉴定了所获得的非对映异构体加合物。简要讨论了机理以及试剂构型与烯丙基锡化反应选择性的关系。
syn-Allylstannation of N-Acyliminium Intermediates by Tributyl[γ-(silyloxy)allyl]stannanes: A Key Reaction for the Diastereoselective Synthesis of Polyhydroxypiperidines and Polyhydroxyazepanes
作者:Floris Chevallier、Alexandre Lumbroso、Isabelle Beaudet、Erwan Le Grognec、Loïc Toupet、Jean-Paul Quintard
DOI:10.1002/ejoc.201100302
日期:2011.8
The allylstannation of N-alkenyl N-acyliminium intermediates by tributyl[gamma-(silyloxy)allyl]stannanes afforded the expected adducts with a high syn-selectivity (up to 99: 1). Ensuing ring-closing metathesis afforded dehydropiperidines or dehydroazepanes which were engaged in a stereoselective dihydroxylation reaction leading to polyhydroxypiperidines or polyhydroxyazepanes in good yields. This sequence
Addition of γ-silyloxyallyltins on ethyl glyoxylate: evaluation of the influence of the experimental conditions on the stereochemical course of the reaction
作者:Alexandre Lumbroso、Piotr Kwiatkowski、Anna Blonska、Erwan Le Grognec、Isabelle Beaudet、Janusz Jurczak、Slawomir Jarosz、Jean-Paul Quintard
DOI:10.1016/j.tet.2009.12.037
日期:2010.2
Ethyl glyoxylate was reacted with α-substituted γ-(t-butyldimethylsilyloxy)-allyltributyltin in order to obtain selectively each diastereomer of ethyl 3-(t-butyldimethylsilyloxy)-2-hydroxyhex-4-enoate and subsequently the corresponding diols. Diastereomers syn-E, anti-E and anti-Z were obtained in good yields with good to high selectivities and the obtained results were rationalized by consideration