Chiral N-dienyl-L-pyroglutamic esters in asymmetric hetero-Diels-Alder reactions with acylnitroso dienophiles

Article abstract of DOI:10.1016/0040-4020(95)01111-0

Asymmetric Diels-Alder reaction of the N-dienyl-L-pyroglutamic esters 1a-h with acyl nitroso dienophiles 4a-h gave diastereoisomeric adducts 6a-n, 7a-n with 12-90% de, depending on solvents and temperature. An interpretation was given. The 'allylic effect' (π(C=C) - σ*(N-C) MO interactions) was found to be effective to account for the conformations of the adducts.