GB1496427A - Beta-ketoisocyanates and the isomeric 1,3-oxazines - Google Patents

Abstract

1496427 #-Ketoisocyanates and isomeric 1,3- oxazines thereof BAYER AG 17 Feb 1975 [23 Feb 1974 16 Nov 1974] 6541/75 Heading C2C Compounds of the formula or an isomeric 1,3-oxazine corresponding to the tautomeric formulµ wherein R<SP>1</SP>, R<SP>2</SP> and R<SP>3</SP> are the same or different and each represents hydrogen, an optionally substituted alkyl or cycloalkyl radical with up to 6 carbon atoms or an optionally substituted aryl radical, and R<SP>4</SP> represents an optionally substituted alkyl or cycloalkyl radical with up to 6 carbon atoms, or an optionally substituted aryl radical, and in which R<SP>1</SP> and R<SP>2</SP> and/or R<SP>3</SP> and R<SP>4</SP>, and/or R<SP>1</SP> or R<SP>2</SP> and R<SP>4</SP>, together with the carbon atoms substituted by them, may also form a carbocyclic ring, provided that R 3 and R 4 do not complete a benzene ring, may be obtained by reacting phosgene with a #-ketoamine of the formula In one embodiment the #-ketoamines, or salts thereof may be reacted with phosgene in an inert solvent at 100-200‹ C. and the 1,3-oxazines obtained may be converted to the isomeric #- ketoisocyanates by pyrolysis, preferably under a reduced pressure at 120-300‹ C. In another embodiment, the #-ketoamines may be reacted with phosgene in the presence of a base at -30‹ to +35‹ C., and the #-ketoisocyanate product may be cyclized in the presence of catalytic quantities of acid, preferably at elevated temperature in a solvent to form the 1,3- oxazine; the reaction may also be carried out in a two-phase system of water and an inert water-immiscible solvent with the pH of the aqueous phase being adjusted to 7 on completion of the reaction. The products possess plant-growth regulant properties.