D-luciferin, the natural substrate of firefly luciferases. A new synthesis of2-cyano-6-hydroxybenzothiazole has been realized starting from the reaction of 1,4-benzoquinone with L-cysteine ethyl ester, followed by oxidation-cyclization of the intermediate ethyl (R)-2-amino-3-(2,5-dihydroxyphenylsulfanyl)propanoate hydrochloride to 2-carbethoxy-6-hydroxybenzothiazole. A suitable protection of this intermediate
2-Cyano-6-hydroxybenzothiazole 是合成
D-荧光素(萤火虫
荧光素酶的天然底物)的关键中间体。从1,4-苯醌与
L-半胱氨酸乙酯的反应开始,然后中间体乙基(R)-2-
氨基-3-( 2,5-二羟基苯
硫基)
丙酸酯盐酸盐转化为 2-carbethoxy-6-hydroxybenzothiazole。对该中间体进行合适的保护并转化为相应的腈,在脱保护后得到
2-氰基-6-羟基苯并噻唑(1,4-苯醌的产率为 32%)。该腈与
D-半胱氨酸反应,在室温下以几乎定量的产率 (90-95%) 提供
D-荧光素。