Diels-Alder Reactions of Isoprene and 1,3-Butadiene with Nitroheptenes Derived from Sugars

Abstract
The Diels-Alder cycloadditions of 1,3-butadiene and isoprene with D-galacto- and D-manno-(E)-nitroalkenes are described. These reactions showed an unlike stereoselectivity, as a consequence of the configuration of the adjacent chiral centre to the dienophilic double bond. For isoprene adducts, the favored regioisomers were those in which the nitro and the methyl groups on cyclohexene rings are in a 1,4-relationship. Assignment of absolute configurations at the new chiral centres in the adducts were based on NMR data and polarimetric correlations with known compounds.