Synthesis of Polyfunctionalized 4H-Pyrans

Table 4

Synthesis of substituted pyrans from ethyl acetoacetate via Scheme 1.^a,b

Entry	R	Product	Time (h)	% Yield^c	m.p. (°C)
1	3-NO2C6H4	2a	2.5	91	182– 184 [12]
2	4-NO2C6H4	2b	2.5	88	180- 181 [12]
3	4-ClC6H4	2c	3.0	83	173- 174 [12]
4	Ph	2d	3.0	75	194– 196 [12]
5	4-MeOC6H4	2e	4.0	77	135- 136 [12]
6	3,4,5-(OMe)3C6H2	2f	5.0	81	165-166
7	3-OHC6H4	2g	3.5	86	161- 162 [12]
8	n-C6H13	2h	6	82	163–165

^aAll reactions were carried out at room temperature; ^bequimolar ratio of all the reactants with 30 mg Amberlyst A21/mmol of aldehyde; ^cisolated yields.