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A Novel Controlling Method for Regio- and Stereoselectivity in the Carbonyl-Allylation using Allylic Tin Reagents

使用烯丙基锡试剂控制羰基烯丙基化区域选择性和立体选择性的新方法

基本信息

批准号：
09640636
负责人：
TAKUWA Akio
金额：
$ 1.79万
依托单位：
SHIMANE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

In the light promoted reaction of gamma -substituted allyltin reagents with carbonyl compounds, the allylic groups could be introduced predominantly at their a-position into carbonyl carbon via single electron-transfer from allylic tin reagent to the photoexcited triplet carbonyl compounds. The photoinduced alpha-allylation proceeds stereospecifically, for example, (E)- and (Z)-gamma-alkoxyallylic tin reagents give (R)- and (Z)-a-homoallylic alcohols. The photoinduced allylic 1,3-rearrangement has been also investigated in detail by direct excitation of y -substituted allyltin compounds.In the reaction between a-alkoxyaldehydes and pentadienyltin, each of the possible four regio- and stereolsomers, syn-gamma-, anti-gamma-, syn-epsilon-, and syn-e-adducts, was selectively synthesized by the use of an appropriated combination of alkoxy groups. Lewis acids, and solvents. When MgBr2 was used as Lewis acid, the protecting a-oxygenated aldehyde such as benzyl (Bn) or methoxymethyl (MOM) affoided gamma-syn-adduct, but the combination of BF3OEt2 with a-protected aldehyde by tert-butyldimethylsilyl (TBS) gave a-anti-adduct, On the other hand, SnCI4 was found to give syn-gamma-adduct in the reaction with the benzyl protected aldehyde, When the reaction of the aldehyde protected by TBS was performed in the presence of InCl3 in ethanol media, gamma-anti-adduct was produced. Thus, the regio- and stereocontrolled allylation and pentadienylation of carbonyl group could be achieved by a appropriate combination of the reaction promoter and the protecting group of aldehyde.

在γ-取代烯丙基锡试剂与羰基化合物的光促进反应中，烯丙基锡试剂通过单电子转移到光激发三重态羰基化合物上，烯丙基基团主要在其α位引入羰基碳中。光诱导的α-烯丙基化立体专一地进行，例如，（E）-和（Z）-γ-烷氧基烯丙基锡试剂得到（R）-和（Z）-α-高烯丙醇。在α-烷氧基醛与α-烯基锡的反应中，通过适当的烷氧基组合，选择性地合成了syn-gamma-、anti-gamma-、syn-gamma-和syn-e-加合物四种可能的区域和立体异构体。刘易斯酸和溶剂。以MgBr_2为刘易斯酸时，α-含氧保护醛如苄基（Bn）或甲氧甲基（CH_3）等生成γ-顺式加合物，而以叔丁基二甲基硅烷基（TBS）为保护剂时，BF_3 OEt_2与α-保护醛反应生成α-反式加合物，而SnCl_4与苄基保护醛反应生成γ-顺式加合物。在InCl_3存在下，乙醇介质中，TBS保护的醛与InCl_3反应，生成γ-反加合物。因此，通过反应促进剂和醛的保护基的适当组合，可以实现羰基的区域和立体控制的烯丙基化和烯丙基化。