Microwave-assisted one-pot regioselective synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines

Wei-Min Dai*, Xuan Wang and Chen Ma

*Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China, Email: chdaiust.hk

W.-M. Dai, X. Wang, C. Ma, Tetrahedron, 2005, 61, 6879-6885.

DOI: 10.1016/j.tet.2005.04.072

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Abstract

A regioselective one-pot synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines under microwave heating starts from commercially available 2-aminophenols. Base-mediated regioselective O-alkylation with 2-bromoalkanoates gives acyclic intermediates. A subsequent intramolecular amidation reaction furnishes the desired products in good yields.

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Key Words

1,4-Benzoxazines, benzo-fused O-Heterocycles, benzo-fused N-Heterocycles, 2-Aminophenols, Microwave, Regioselectivity, Annulation, Microwave Synthesis

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ID: J72-Y2005-2980