A Convenient Procedure for the Synthesis of N-Acetyl-5,6-dihydro-2H-1,2-oxazines

Abstract

Acetylation of 5,6-dihydro-4H-1,2-oxazines with an acetyl bromide/acetic anhydride mixture provides a general and quite simple procedure for the synthesis of N-acetyl-5,6-dihydro-2H-1,2-oxazines.

Key words

1,2-oxazines - acylations - cycloadditions - γ-amino acids - hydroxylamines

References

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10

The reaction of oxazine 1a with lithium diisopropylamide, butyllithium, or butyllithium/potassium tert-butoxide at 0 °C, -30 °C, and -50 °C, respectively (for two hours), followed by treatment with acetyl chloride led to the recovery of the initial oxazine 1a in almost quantitative yield after treatment of the resulting mixtures with water.