Dimethyl fumarate, with cyclopentadiene

The stereochemistry of the adduct obtained in many Diels-Alder reactions can be selected on the basis of two empirical rules formulated by Alder and Stein in 1937. According to the cis principle , the relative stereochentistry of substituents in both the dienophile and the diene is retained in the adduct. That is, a dienophile with trans substituents will give an adduct in which the trans configuration of the substituents is retained, while a cis disubstituted dienophile will form an adduct in which the substituents are cis to each other. This aspect is often referred to as the stereospecific nature of the Diels-Alder reaction. For example, in the reaction of cyclopentadiene with dimethyl maleate, the cis adducts 74 and 75 are formed, while in the reaction with dimethyl fumarate, the trans configuration of the ester groups is retained in the adduct 76 (3.64). 

Predict the products of the following reactions (show the stereochemistry clearly) (a) trans-1,3-pentadiene with 2-butenedioic anhydride (maleic anhydride) (b) 1,3-cyclopentadiene with dimethyl trans-2-butenedioate (dimethyl fumarate). 

Diels-Alder reactions are stereospecific with respect to the E- and Z-relationships in both the dienophile and the diene. For example, addition of dimethyl fumarate and dimethyl maleate with cyclopentadiene is completely stereospecific with respect to the cis or trans orientation of the ester substituents. 

When (67) was treated with a wide variety of cycloaddition reagents under various conditions, it behaved as a diene or a dienophile but not as a 1,3-dipole. As a dienophile it reacted with 2,3-dimethyl-1,3-butadiene to give (70) and with cyclopentadiene to give an analogous product. As a diene it reacted with [2.2.1] bicycloheptene to give (72), presummably via (71), by loss of carbon monoxide and hydrogen. No products were isolated when (67) was treated with maleic anhydride, dimethyl acetylene-dicarboxylate, diphenylacetylene, dimethyl fumarate, carbon disulfide, isobutyl vinyl ether, cyclohexene, and cyclopentene. 

Complete stereoselectivity occurs in the Diels-Alder reaction through syn addition of the dienophile to the diene. Hence, the reaction of dimethyl fumarate and dimethyl maleate with cyclopentadiene yields the trans and cis adducts, respectively (Scheme 26.1).29... 

The first report of the use of racemic sulfinyl maleates as dienophiles appeared in 1983 [85]. This paper described the synthesis of 2-phenylsulfmyl maleate and fumarate, but only the reaction of cyclopentadiene with the first ( )-87, a synthetic equivalent of dimethyl acetylenedicarboxylate, was studied. The reaction takes place at room temperature on silica gel and the stereochemistry of the adducts remained undetermined because the isolated product is the compound resulting from the pyrolytic sulfinyl elimination, which occurs spontaneously under the reaction conditions used (Scheme 46). 

Toward asymmetric Diels-Alder reaction in industrial chemistry, the use of menthyl group as an inexpensive and recyclable chiral auxiliary was investigated. As a pioneering work in this field, Yamamoto reported aluminum Lewis acid-catalyzed Diels-Alder reaction of dimethyl fumarate with cyclopentadiene (Scheme 6.119) [143]. Later, more suitable reaction conditions for large-scale synthesis was investigated. 

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