CYCLOADDITION REACTIONS OF PYRIDINIUM AND RELATED AZOMETHINE YLIDES
CYCLOADDITION REACTIONS OF PYRIDINIUM AND RELATED AZOMETHINE YLIDES
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DOI：
10.1021/jo00057a029
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发表时间：
1993-02-26
影响因子：
3.6
通讯作者：
ZHI, L
中科院分区：
文献类型：
--
作者：
PADWA, A;AUSTIN, DJ;ZHI, L
在Rh(H)催化下，α-重氮苯乙酮在2-甲硫基吡啶和乙酰二甲酸二甲酯存在下的反应生成3-benzoyl-1，2-dicarbomethoxy-3，5-dihydro-5-(methylthio)-indolizine.环加合物的形成通过氮孤对亲电的酮卡宾的攻击而形成的吡啶叶立德进行。1-重氮-3-[(2-吡啶)硫代]-2-丙酮也发生了相应的环化反应。Rh(II)催化的1-(3‘-重氮丙酮基)-2-吡啶酮与DMAD的反应也得到了亚甲基叶立德的环加合物。初始反应包括通过酮类卡宾在酰胺基氧原子上的分子内环化生成预期的羰基叶立德偶极。随后的质子交换产生热力学上更稳定的亚甲基叶立德，它被DMAD捕获。硫代苯并恶唑通过酮类卡宾环合而得的亚甲基叶立德环加合物也可生成。当使用1-重氮-3-[(2-苯并恶唑基)硫代]-2-丙酮时，最初形成的环加合物发生了随后的1，3-Sigmatrotic硫代移动。2-(4-重氮-3-氧基丁基)苯并恶唑发生了类似的环化反应。除了进行偶极环加成反应外，由该苯并恶唑形成的高度稳定的偶极还会失去一个质子来生成环乙烯酮N，O-缩醛。该化合物进一步与DMAD反应生成一种新的酚内酰胺，其结构经X-射线晶体结构分析确定。
The Rh(H)-catalyzed reaction of alpha-diazoacetophenone in the presence of 2-(methylthio)pyridine and dimethyl acetylenedicarboxylate gave 3-benzoyl-1,2-dicarbomethoxy-3,5-dihydro-5-(methylthio)-indolizine. The formation of the cycloadduct proceeds via a pyridinium ylide formed by attack of the nitrogen lone pair on the electrophilic keto carbenoid. A related cyclization occurred using 1-diazo-3-[(2-pyridyl)thio]-2-propanone. The Rh(II)-catalyzed reaction of 1-(3'-diazoacetonyl)-2-pyridone with DMAD was also found to give cycloadducts derived from an azomethine ylide. The initial reaction involves generation of the expected carbonyl ylide dipole by intramolecular cyclization of the keto carbenoid onto the oxygen atom of the amide group. A subsequent proton exchange generates the thermodynamically more stable azomethine ylide which is trapped by DMAD. Azomethine ylide cycloadducts derived from keto carbenoid cyclization onto a thiobenzoxazole are also formed. When 1-diazo-3-[(2-benzoxazolyl)thio]-2-propanone was used, the initially formed cycloadduct underwent a subsequent 1,3-sigmatropic thio shift. An analogous cyclization occurred using 2-(4-diazo-3-oxobutyl)benzoxazole. In addition to undergoing dipolar cycloaddition, the highly stabilized dipole formed from this benzoxazole loses a proton to produce a cyclic ketene N,O-acetal. This compound reacts further with DMAD to eventually produce a novel phenolic lactam whose structure was established by an X-ray crystal structure analysis.