Microwave-assisted one-pot U-4CR and intramolecular O-alkylation toward heterocyclic scaffolds

The one-pot U-4CR and intramolecular O-alkylation sequence starting from 2-aminophenols in combination with alpha-bromoalkanoic acids, aldehydes, and isocyanides under controlled microwave heating has been established for a rapid access to highly functionalized 3,4-dihydro-3-oxo-2H-1,4-benzoxazines. With appropriate substitutions on the 1,4-benzoxazines, a microwave-assisted Cu-catalyzed intramolecular amidation was performed to furnish a novel class of heterocyclic conjugates of 1,4-benzoxazines with a 2-oxindole linked through a C-N single bond. (c) 2006 Elsevier Ltd. All rights reserved.