Simple Generation of Ester-Stabilized Azomethine Ylides from 2-Amino Esters and Carbonyl Compounds. Stereochemistry of Their Cycloadditions

Article abstract of DOI:10.1246/bcsj.60.4067

Condensation of 2-amino esters with carbonyl compounds leads to simple generation of ester-stabilized azomethine ylides which are trapped by olefinic dipolarophiles as cycloadducts.Anti ylides are exclusively involved in the cycloadditions when N-substituted 2-amino esters are employed for the ylide generation, while syn ylides from N-unsubstituted 2-amino esters.Relative stability among all possible ylide isomers has been inspected and the selective involvement of particular ylidic forms has been explained on the ground of 1,5-dipole interaction or hydrogen bonding stabilization.Endo- and exo-selectivity of the cycloadditions is also discussed.