REGIOCONTROLLED NUCLEOPHILIC-ADDITION TO THE CARBONYL AND IMINO GROUPS IN THE REACTION OF 2-ARYLAMINO-2-METHOXY-1-PHENYLETHANONES WITH SIMPLE LITHIUM ESTER ENOLATES

The nucleophilic addition of lithium ester enolates 3 to 2-arylamino-2-methoxy-1-phenylethanones I (synthetic equivalents of the related phenylglyoxal anils 2) Is reported. While enolates derived from α,α-dialkyl methyl esters, 3a and 3b, give addition products by attack at either the carbonyl (kinetic products) or the imino groups through a thermally controlled process, those derived from methyl dimethoxyacetate, methyl acetate and methyl propionate, 3c, 3d, and 3e. respectively, only lead to addition products to the carbonyl group. On the basis of the Isolation of all these compounds as stable products and of some transformations and crossover experiments a reasonable mechanism Is proposed for the whole process. In all cases, addition products at the imino groups can also be obtained by the SiO2-catalyzed rearrangement of the corresponding kinetic addition compounds. The synthesis of some substituted 4-benzoyl-β-lactams 8a-g Is a particularly significant feature of this work. © 1990.