Facile and Promising Method for Michael Addition of Indole and Pyrrole to Electron-Deficient trans-β-Nitroolefins Catalyzed by a Hydrogen Bond Donor Catalyst Feist’s Acid and Preliminary Study of Antimicrobial Activity

Table 1

Condition optimization of Feist’s acid catalysis in the addition of indole^a (4) to β-nitro-styrene (2a).

Entry	Solvent	𝑡 (°C)	Time (h)	Cat. mol%	Yield^b (%)
1	ACN	60	60	10	49
2	CH2Cl2	40	16	10	—
3	THF	50	72	10	—
4	MeOH	60	72	10	62
5	DMF	60	24	10	96
6	𝑖PrOH	60	42	10	98
7	AcOH	60	18	10	91
8	Xylene	60	42	10	88
9	Tolene	60	42	10	89
10	Benzene	60	42	10	86
11	EtOH	rt	120	0	—
12	EtOH	60	72	0	—
13	EtOH	40	60	5	59
14	EtOH	50	42	10	95
15	EtOH	50	42	15	98
16	EtOH	50	42	20	98

aThe reactions were performed on an 0.425 mmol scale; ^bthe isolated yield after column purification.