Model Michael addition in heterogeneous environment catalyzed with IIa–d^a.

Entry	Catalyst	Reaction time [h]	Conversionb (isol. yieldc) [%]	eed [%]	syn : antib
1	IIa	72	51 (36)	78	95 : 5
2	IIb	72	49 (18)	90	90 : 10
3	IIc	72	10 (7)	58	83 : 17
4	IId	72	25 (10)	86	94 : 6

^aReaction conditions: nitrostyrene 0.25 mmol, cyclohexanone 1 ml, catalyst 0.05 mmol, acetic acid 0.035 mmol, t = 25 °C, reaction time = 72 h.

^bDetermined by ¹H NMR.

^cPurified by column chromatography (hexane : ethyl acetate = 5 : 1).

^dDetermined by chiral HPLC (column YMC Amylose C, mobile phase heptane : IPA = 9 : 1, flow rate 0.7 ml min⁻¹).