The Michael reaction of various nitroalkanes with conjugated enones can be performed in NaOH 0.025 M and in the presence of cetyltrimethylammonium chloride (CTACl) as cationic surfactant, without any organic solvent. Good yields of the products are obtained even with hindered starting materials.
Ballini, R., & Bosica, G. (1996). The Michael reaction of nitroalkanes with conjugated enones in aqueous media. Tetrahedron Letters, 37(44), 8027–8030. https://doi.org/10.1016/0040-4039(96)01816-3