Synthesis of Benzothiophene-Fused Pyran Derivatives via Piperidine Promoted Domino Reaction

Table 2

Scope of the domino .

Entry	R^1	R^2	Time [min]	Yield
1	5-CH3(1a)	COOEt	15	83 (3a)
2	5-CH3(1b)	COOBn	20	52 (3b)
3	5-CH3(1c)	o-PhCl	10	84 (3c)
4	5-CH3(1d)	m-PhCl	10	99 (3d)
5	5-CH3(1e)	p-PhMe	15	69 (3e)
6	5-F(1f)	COOEt	15	60 (3f)
7	5-Br(1g)	COOEt	20	59 (3g)
8	6-OMe(1h)	COOMe	15	71 (3h)
9	7-Cl(1i)	Phenyl	10	80 (3i)

conditions: 0.2 mol thioaurone 1, 0.4 mol malononitrile 2a, 2.0 mL DCM at room temperature, and 10% mol piperidine as the catalyst. yields.