According to the present invention, it becomes possible to perform a process for converting into an α-substituted cysteine represented by general formula (1) or a salt thereof at low cost and on an industrial scale by employing a process that is routed through a compound represented by general formula (3) to a compound represented by general formula (6). Particularly, by employing a process that is routed through a compound represented by general formula (7-2), it becomes possible to detach a tert-butyl protection group in a simple manner and to produce the compound represented by general formula (1) with high purity. Furthermore, by employing a process that is routed through tert-butylthiomethanol or a process that is routed through a compound represented by general formula (9), it becomes possible to produce a compound represented by general formula (2) without generating bischloromethylether that is an oncogenic substance. In the production of an α-substituted-D-cysteine or a salt thereof, it becomes possible to perform a process for converting the compound represented by general formula (2) into a compound represented by general formula (3S) in one step by allowing an enzyme or the like to act on the compound represented by general formula (2).
根据本发明,通过通式(3)所代表的化合物到通式(6)所代表的化合物的过程,可以低成本和工业规模地进行通式(1)所代表的α-取代半胱
氨酸或其盐的转化过程。特别是通过通式(7-2)所代表的化合物,可以简单地分离叔丁基保护基团,并生产出高纯度的通式(1)所代表的化合物。此外,通过采用叔丁基
硫代
甲醇或通式(9)所代表的化合物的工艺,可以生产通式(2)所代表的化合物,而不会产生致癌物质双
氯甲基醚。在生产α-取代的-
D-半胱氨酸或其盐的过程中,可以通过让酶或类似物作用于通式(2)所代表的化合物,一步将通式(2)所代表的化合物转化为通式(3S)所代表的化合物。