K₂CO₃/Al₂O₃: An efficient and recyclable catalyst under solvent free conditions for the reaction of electron-deficient nitro-olefins with 1,3-dicarbonyl compounds

Figures & data

Scheme 1. Synthesis of various Michael adducts 4a-h using KCA as a catalyst.

Table 1. Synthesis of compound 4a using KCA as catalyst

Entry	Catalyst (g)	T (°C)	Time (min)	Yield (%)^a
1	None	140	60	19
2	KCA (0.05)	80	15	52
3	KCA (0.05)	110	15	61
4	KCA (0.05)	140	15	64
5	KCA (0.10)	80	15	68
6	KCA (0.10)	110	15	71
7	KCA (0.10)	140	15	75
8	KCA (0.15)	80	20	79
9	KCA (0.15)	110	15	83
10	KCA (0.15)	140	8	98, 97, 96, 95, 95^b
11	KCA (0.20)	140	10	96
12	K2CO3 (0.50)	140	60	62

^a Isolated yields.

^b The same catalyst was used for each of five runs.

Table 2. Scope of the malonate Michael addition with nitroalkenes 3a–e

Entry	R	Ar	Product 4	Time (min)	Yield (%)^a
1	Et (1)	phenyl (3a)	4a	8	98
2	Et (1)	3,4-methylenedioxyphenyl (3b)	4b	13	92
3	Et (1)	4-methoxyphenyl (3c)	4c	13	93
4	Et (1)	2-furyl (3d)	4d	12	94
5	Et (1)	2-thienyl (3e)	4e	12	90
6	Me (2)	phenyl (3a)	4f	9	95
7	Me (2)	4-methoxyphenyl (3c)	4 g	13	92
8	Me (2)	2-furyl (3e)	4 h	11	91

^a Isolated yields.