Studies on Conformation and Reactivity. VIII. Stereochemical Aspects of the Diels-Alder Reaction of Diethyl Azodicarboxylate with Steroid Homodienes. (1)

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The Diels-Alder reaction of diethyl azodicarboxylate (I) with steroid 2,4-and 5,7-dienes and its stereochemistry were reported. The azo-ester (I) reacted with cholesta-2,4-diene (II) to afford three one-to-one adducts, i.e. the 1,4-adduct (IV) at 2α and 5α positions and two addition-abstraction adducts (V and VI) isomeric at 3 position, and diethyl hydrazinedicarboxylate (VII) in 21.4%, 10.8%, 5.2%, and 12.2% yields respectively. The 1,4-adduct (IV) was chemically modified to its dihydro derivatives, VIII and IX. The reaction of the azo-ester (I) with 3β-benzoyloxycholesta-5,7-diene (III), on the other hand, led to the formation of two one-to-one adducts, i.e. the 1,4-adduct (XI) at 5α and 8αpositions and an addition-abstraction adduct (XII) at 7α position in 4.2% and 36% yields respectively. The 1,4-adduct (XI) was converted to its dihydro derivative (XIII). The result showed that whereas with the 2,4-diene (II) as substrate, the 1,4-addition and addition-abstraction reactions take place to the almost same extent, with the 5,7-diene (III) as substrate the latter reaction is preferred. Stereochemical aspects of the different reactivity of the azo-ester (I) toward those dienes were discussed.
公益社団法人日本薬学会の論文
1970-03-25