Diastereoselective allylation of α-ketoamides bearing camphor N-tosylpyrazolidinone auxiliary: efficient synthesis of highly optically active two stereoisomers
Complementary allylation conditions were developed for the synthesis of both diastereomers of tertiary homoallylic alcohols. Treatment of camphor N-tosylpyrazolidinone derived α-ketoamides with allyltributylstannane afforded both the individual homoallylic alcohols in high optical purity (up to 98% de) when the reaction was carried out in the presence of Sn(OTf)2 and PdCl2, respectively. The stereochemical
开发了互补的烯丙基化条件以合成叔均烯丙基醇的两种非对映异构体。当反应分别在Sn(OTf)2和PdCl 2的存在下进行时,用烯丙基三丁基锡烷处理樟脑N-甲苯磺酰基吡唑烷酮衍生的α-酮酰胺可提供高光学纯度(最高98%de)的两种均烯丙基醇。基于13 C NMR和FTIR研究,提出了反应中的立体化学结果和立体选择性的逆转。
Indium-mediated diastereoselective allylation reactions: preparation of tert-α-hydroxy acids
作者:Jeong Ah Shin、Joo Hwan Cha、Ae Nim Pae、Kyung Il Choi、Hun Yeong Koh、Han-Young Kang、Yong Seo Cho
DOI:10.1016/s0040-4039(01)01064-4
日期:2001.8
Indium-mediated allylation reactions of α-ketoimides derived from Oppolzer's sultam were accomplished in aqueous THF in good yields and excellent diastereomeric excesses. It could be a useful method for the preparation of enantiopure t-α-hydroxy acids. When the substituent of α-ketoimides was changed from phenyl to thiophenyl or furyl group, diastereoselectivity decreased in comparison to N-phenyl
Diastereoselective addition of allylic reagents to chiral α-ketoimides derived from Oppolzer's sultam
作者:Katarzyna Kiegiel、Janusz Jurczak
DOI:10.1016/s0040-4039(98)02470-8
日期:1999.1
Additions of allylmagnesium chloride and allyl bromide in the presence of zinc dust to N-methyl- and N-phenylglyoxyloyl-(2R)-bornane-10,2-sultam and the Lewis acid-mediated additions of allyltrimethylsilane to these chiral α-ketoimides were studied. High diastereoselection in these reactions was observed, and in the case of the allyltrimethylsilane/TiCl4 additions, a change of direction of asymmetric
Highly diastereoselective allylation and reduction of chiral camphor-derived α-ketoamides
作者:Neelesh A. Kulkarni、Shy-Guey Wang、Li-Chen Lee、Huei Ru Tsai、Uppala Venkatesham、Kwunmin Chen
DOI:10.1016/j.tetasy.2006.01.011
日期:2006.2
The diastercoselective allylation and reduction of camphor-derivcd alpha-ketoamides to give optically enriched a-hydroxyl amides with high to excellent stereoselectivities are described. Allylation was carried out using allyltributylstannane in the presence of a stoichiometric amount of a Lewis acid to afford the desired homoallylic alcohols in relatively high chemical yields (up to 98%) and stereoselectivities (LIP to 98% de). Diastereoselective reductions were performed with the relatively bulky hydride K-Selectride at -78 degrees C to give the corresponding a-hydroxy amides in excellent chemical yields (LIP to 98%) and stereoselectivities (up to 98% de). The absolute configuration of the new stereogenic center of the major diastereomer was established by X-ray crystallographic analysis. Finally, stereochemical induction and the Lewis acid dependent reversal of stereoselectivity is described. (c) 2006 Elsevier Ltd. All rights reserved.
Asymmetric Hetero-Diels-Alder Addition of 1-Methoxybuta-1,3-diene to (2R)-N-Pyruvoyl- and (2R)-N-(Phenylglyoxyloyl)bornane-10,2-sultam