Lewis acid induced homoallylic C-alkylation. A new approach to C-glycosides
Lewis acid induced homoallylic C-alkylation. A new approach to C-glycosides
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DOI：
10.1021/jo00235a008
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发表时间：
1987-12
影响因子：
3.6
通讯作者：
J. Herscovici;Sylvie Delatre;K. Antonakis
中科院分区：
文献类型：
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作者：
J. Herscovici;Sylvie Delatre;K. Antonakis
作为我们对开发用于制备C-糖苷的新方法的持续兴趣的一部分，我们最近探索了烯烃与全乙酰化的糖化物的反应。4 5用这种方法可以以良好的产率和高度的立体选择性制备2 '，3'-不饱和C-糖苷，另外还可以直接引入多官能糖苷配基。为了研究1-醛和2-酮C-糖苷的直接制备，我们现在已经将注意力转向烯丙醇的刘易斯酸诱导的反应。这一想法源于在SnCl 4存在下，二乙酰L-鼠李醛（1）与3-甲基-3-丁烯-1-醇（2）6（当量1）的反应，该反应清楚地表明活化的烯烃比醇与全乙酰化的糖基的反应更快。这一结果促使我们研究与2-甲基-2-丙烯-1-醇（4）的衍生物的类似反应，以研究丙酰基合成子的可能直接引入。
As part of our ongoing interest in the development of new procedures for the preparation of C-glycosides1 2" 3 we have recently explored reaction of olefins with peracetylated glycals. 4 5By this methodology 2', 3'-unsaturated C-glycosides could be produced in good to excellent yields with an high degree of stereoselectivity, allowing in ad-dition the direct introductionof polyfunctional aglycons. We have now turned out our attention to Lewis acid in-duced reactions of allylic alcohols® in orderto investigate a straightforward preparation of 1-aldo and 2-keto C-glycosides.This idea originates from the reaction of diacetyl L-rhamnal (1) with 3-methyl-3-buten-l-ol (2) 6 (eq 1) in the presence of SnCl4 which shown clearly that activated olefins reacted faster than alcohols with peracetylated glycals. This result prompted us to examine analogous reactions with derivatives of 2-methyl-2-propen-l-ol (4) in order to investigate the possible direct introduction of a propionyl synthon.