抄録
Pyridoxal or its phosphate reacts with DL-homocystcine in aqueous solution to give 2-(3-hydroxy-5-hydroxymethyl-2-methylpyridyl-4)-tetrahydro-1,3-thiazine-4-carboxylic acid (I) or 2-(3-hydroxy-5-phosphoryloxymethyl-2-methyl-pyridyl-4)-tetrahydro-1,3-thiazine-4-carboxylic acid (II). (I) and (II) are comparatively stable in slightly acidic solution and crystallize from the reaction solution. (I) is obtained in a good yield by an addition of pyridoxal hydrochloride to a solution containing DL-homocysteine thiolactone hydrochloride. Polymorphism is observed in (I), the one with mp. 128-130℃ which is a stable form and the other with mp. 159-160℃ which is a semistable form. These two forms of (I) are interconvertible. UV spectra of the two are identical, however the IR spectra are different in a sharp absorption at ν 1735 cm^<-1> which is seen only in the former. The chemical structure of (I) is confirmed by means of NMR spectrum.
