A New Approach to 1,4-Oxazines and 1,4-Oxazepines via Base-Promoted Exo Mode Cyclization of Alkynyl Alcohols: Mechanism and DFT Studies
Jaya Kishore Vandavasi, Wan-Ping Hu, Hsing-Yin Chen, Gopal Chandru Senadi, Chung-Yu Chen and Jeh-Jeng Wang*
*Departments of Medicinal and Applied Chemistry, Biotechnology, and Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan, Email: jjwangkmu.edu.tw
J. K. Vandavasi, W.-P. Hu, H.-Y. Chen, G. C. Senadi, C.-Y. Chen, J.-J. Wang, Org. Lett., 2012, 14, 3134-3137.
DOI: 10.1021/ol301219c (free Supporting Information)
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A solvent- and metal-free regioselective cyclization affords 1,4-oxazine and 1,4-oxazepine derivatives as exo-dig products. Substrates for the cyclization step can be produced in a highly diastereomeric fashion by Grignard reaction as key synthetic step following Cram’s rule.
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