Dimethyl fumarate Lewis acid promoted

The discovery that Lewis acids can promote Diels-Alder reactions has become a powerful tool in synthetic organic chemistry. Yates and Eaton [4] first reported the remarkable acceleration of the reactions of anthracene with maleic anhydride, 1,4-benzoquinone and dimethyl fumarate catalyzed by aluminum chloride. The presence of the Lewis-acid catalyst allows the cycloadditions to be carried out under mild conditions, reactions with low reactive dienes and dienophiles are made possible, and the stereoselectivity, regioselectivity and site selectivity of the cycloaddition reaction can be modified [5]. Consequently, increasing attention has been given to these catalysts in order to develop new regio- and stereoselective synthetic routes based on the Diels-Alder reaction. 

In 196146 the initial work on ( —)-(/t)-dimenthyl fumarate (l)47 was revised and a diastereomeric ratio of 78.5 21.5 (15,25) for the aluminum chloride promoted addition to 1,3-butadiene (2) was reported. The absolute configuration was established by degradation of the major cycloadduct 3 to threo-2>,4-dimethyl adipic acid (5). Absence of Lewis acids reverses the sense of chiral induction [d.r. 51.2 48.8 (l/ ,27 )]. These observations are rationalized by means of a modified Prelog model. 

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