Affordable Access

Publisher Website

Influence ofN(2)-substitution in the alkylation of (4S)-alkyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones

Authors
Publisher
Elsevier Ltd
Publication Date
Volume
15
Issue
19
Identifiers
DOI: 10.1016/j.tetasy.2004.07.034

Abstract

Abstract 1-Alkylation of O(3)-lactim, N(11)-azaenolate dilithium species derived from N(2)–H compounds 1a and 1b and the lithium azaenolates derived from the N(2)-phenyl and N(2)-(1-arylethyl) substituted compounds 2, 3 and 4 is studied. In 1 the trans-diastereoselectivity of 1-alkylation is controlled by 1,4-asymmetric induction, with some of these products precursors of the ent-ardeemin framework. By contrast in compounds 2– 4, the stabilization of the lithium azaenolate imposed by the phenyl substituent in 2, and the repulsive steric 1,2-interactions present in the initially formed 1,4- trans derivatives of 3 and 4, favour a C(1)-epimerization to the 1,4- cis isomers.

There are no comments yet on this publication. Be the first to share your thoughts.