Phosphoramides and thiophosphoramides were prepared from optically pure C2‐symmetric 1,2‐diamines and were used as chiral organocatalysts in the asymmetric Michael additions of aldehydes and ketones to N‐substituted maleimides. The 1,2‐diphenylethane‐1,2‐diamine derived thiophosphoramide, which could be prepared in good yield in a one‐step procedure, was found to be more active and selective catalyst in the addition of aldehydes to various maleimide derivatives, when compared to sulfonamides having the same backbone. Products resulted in reactions of ketones with maleimides were also obtained in high yields and enantioselectivities. The thiophosphoramide derivative was also efficient in the asymmetric conjugate addition of carbonyl compounds to β‐nitrostyrene and in the reaction of nitromethane with α,β‐unsaturated ketones. Based on results obtained with (thio)phosphoramides in asymmetric additions to maleimides it was suggested that a weaker, more flexible hydrogen‐bonding of the rigid electrophile to the catalyst is responsible for the improved performance of these bifunctional organocatalysts, as compared with sulfonamides.

Gyö rgy Sző llő si* [a] and Viktó ria Kozma [b] Dedicated to Prof. Mihály Bartók on his 85 th birthday.Asymmetric Michael additions of isobutyraldehyde to maleimides catalyzed by optically pure diamines and their sulfonamides were investigated to develop heterogeneous chiral catalysts for these reactions. Encouraging results, i. e. complete transformations and optically pure products, were obtained using para-toluenesulfonamide or methanesulfonamide derivatives. Chiral solid materials were prepared by covalent bonding of the diamines on sulfonyl chloride functionalized supports. Immobilization of the amines was confirmed by FT-IR spectroscopy. The heterogeneous catalyst prepared by bonding optically pure 1,2-diphenylethane-1,2-diamine to polystyrene support was highly enantioselective, giving results approaching those obtained using soluble sulfonamide derivatives. The anchored catalyst was recyclable few times keeping its activity followed by gradual small decrease in conversion, however, still providing high, up to 97 %, enantiomeric excesses. These materials are among the first efficient recyclable catalysts used in the enantioselective Michael addition of aldehydes to maleimides.

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Asymmetric Michael addition of carbonyl compounds to N-substituted maleimides is an important method for obtaining optically pure succinimides, which are important chiral fine chemical intermediates. Environmentally friendly and sustainable procedures...

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Asymmetric Michael additions of carbonyl compounds to N-substituted maleimides are among the most convenient reactions to prepare optically pure succinimide building blocks. Although a few β-amino acids were found to be highly efficient organocatalysts in the addition of α-branched aldehydes, the effect of their structure on the results of these reactions has not yet been investigated. In the present study, we disclose several unexpected and interesting structural effects of aliphatic and cycloaliphatic β-amino acids obtained in the enantioselective conjugate addition of isobutyraldehyde to N-benzylmaleimide. The dependence of the sense of the enantioselectivity on the bulkiness of the substituent on the β-carbon atom, the beneficial spatial arrangements of the functional groups in cis isomers with cyclohexane scaffold and the inversion of the enantioselectivity depending on the absence of a base additive observed with some trans isomers are unprecedented findings. The minor influence of the nitrogen substituent of the maleimide ring on both the reaction rate and the enantioselectivity was also evidenced using alicyclic β-amino acid prepared from an easily available terpene derivative.

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