1957 年 77 巻 9 号 p. 989-992
Methylation of coixol in ether solution with diazomethane and purification through alumina chromatography affords O-methylated compound of m. p. 55° and N-methylated compound of m. p. 103°. From determination by ultraviolet absorption spectra, the ratio of O-methyl- to N-methylcoixol is 40.5:59.5. This fact reveals that coixol is present, at least in the ether solution under application of diazomethane, as a mixture of tautomers of 60% of the lactam type and 40% of the lactim type. Methylcoixol alone can be obtained by the application of sodium methoxide to 2-chloro-6-methoxybenzoxazole. Methylation of coixol with methyl iodide in the presence of alkali affords only N-methylcoixol.
Methylation of 4-, 5-, and 7-methoxy-2(3H)-benzoxazolone with diazomethane and purification by chromatography give the corresponding O-methylated derivatives (m. p. 78°, 40-41.5°, and 58.5-59.5°) and N-methylated derivatives (m. p. 105°, 1.31-132°, and 127-128°).