Synthesis of 1,4-Dihydropyridines Bearing a Carbamate Moiety on the 4-Position

Table 1

Synthesis of various carbamate derivatives (1a–f).

Entry	Phenyl isocyanate	Aldehyde	Carbamate	Time (min)	Yield^a %	M.p. °C
1				20	92	129–133
2				15	96	160–164
3				210	64^b	125–129
4				210	93^b	106–110
5				195	78^b	187–191
6				195	70^b	191–194

aIsolated yield.
^bReaction took place in ethyl acetate.