A new approach to 1,4-oxazines and 1,4-oxazepines via base-promoted exo mode cyclization of alkynyl alcohols: mechanism and DFT studies.
A new approach was developed to synthesize 1,4-oxazine and 1,4-oxazepine derivatives without solvent and metal. Regioselective cyclization occurred to afford exclusively the exo-dig product, and stereochemistry was studied by circular dichroism and specific optical rotation techniques. The Grignard reaction is a key synthetic step to produce high diastereomeric compounds via Cram's rule and was well supported by DFT calculations. A hydroalkoxylation mechanism was proposed and supported by DFT calculations.
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan.
Jaya Kishore
JK
Vandavasi
Wan-Ping
WP
Hu
Hsing-Yin
HY
Chen
Gopal Chandru
GC
Senadi
Chung-Yu
CY
Chen
Jeh-Jeng
JJ
Wang
D000438:Alcohols / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D003500:Cyclization; D005583:Fourier Analysis; D008958:Models, Molecular; D015394:Molecular Structure; D010077:Oxazepines / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry*; D013237:Stereoisomerism
D000438:Alcohols; D000480:Alkynes; D010077:Oxazepines; D010078:Oxazines