Nitroalkenes solubility

Nitroalkenes derived from galactose or other carbohydrates are converted directly into pyrroles substituted with such carbohydrates at the (3-position. They are important precursors for water-soluble porphyrins (Eq. 10.29).34 Such kinds of porphyrins are good candidates for photodynamic therapy of cancer and have been extensively studied. 

Further to this work, the same group published another multicatalytic reaction in aqueous buffer, which involved two aldehydic substrates with similar reactivities but different polarities [11]. The biphasic reaction allowed the differentiation of the two aldehydes, which reacted in a controlled manner to generate the desired cross-product. Two catalysts were used, and each catalyst triggered an individual reaction step in either aqueous or organic phase. L-Proline, soluble in the aqueous phase, catalyzed the addition of nitromethane with the less hydrophobic aldehyde (Scheme 12.6). Diphenylprolinol trimethylsilyl ether 5, which is an efficient catalyst for the conjugated addition of aldehydes to nitroalkenes, catalyzed the reaction of the... 

DiaryIprolinol 83 (Figure 24.28) was used in the addition of aldehydes to 3-nitroacrylates and aryl- and alkyl-substituted nitroalkenes [104]. Water was the reaction medium of choice with benzoic acid as additive to improve the reaction rate and diastereoselectivity. Under these conditions high stereoselectivities were observed. Diarylprolinol 84 (Figure 24.28) was developed with the aim of having a water-soluble catalyst that is easily recoverable in water. Catalyst 84 may be used... 

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