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Regiocontrolled Synthesis of 4‐Halo‐5,6‐Dihydro‐4H‐1,2‐Oxazines; A Novel Route for α‐Fluorovinyl Ketones
Author(s) -
Shatzmiller Shimon,
Lidor Ramy,
Shalom Eytan
Publication year - 1986
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198600006
Subject(s) - chemistry , deprotonation , halogen , halide , medicinal chemistry , proton nmr , stereochemistry , organic chemistry , ion , alkyl
Regiocontrolled deprotonation (e.g. lithiation) of 3‐methyl‐4‐H‐5,6‐dihydro‐1,2‐oxazine 1 is achieved at −65°C. The lithiated compound reacts cleanly with the halogens Cl 2 , Br 2 and I 2 at low temperatures (−65°C) to give the corresponding 4‐halo derivatives. Reaction of the 4‐iodo compound 2a with KF in diethyleneglycol gives the elimination product 4 whereas the bromo compound 2b reacts under substitution to the 4‐fluoro derivatives 5. The fluorooxazine derivatives 8a‐c were converted to the αfluoroenones 11 a‐c via the oxoiminium salts 10a‐c. The U.V. and 1 HNMR of the novel series of halides 2a‐c and 5 were studied.