合成路线1

The treatment of dipeptide S-acetyl-N-(benzyloxycarbonyl)-L-homocysteinyl-L-lysine (I) with L-lysine epsilon aminotransferase (S. paucimobili or E. coli) gives the formyl derivative (II), which is cyclized in acid medium, through the tetrahydropyridinyl intermediate (III), to afford the target pyrido[2,1-b][1,3]thiazepine intermediate (IV). Alternatively, the treatment of dipeptide S-acetyl-N-(benzyloxycarbonyl)-L-homocysteinyl-L-lysine (I) with cell free extracts of E. coli gives N-(benzyloxycarbonyl)-L-homocysteinyl-L-lysine (V), which is digested with L-lysine epsilon aminotransferase (S. paucimobili or E. coli) to yield the formyl derivative (VI). Finally, this compound is cyclized in acid medium to afford the target pyrido[1,2-b][1,3]thiazepine intermediate (IV).