Henry biologically active compounds

In general, the Henry reaction gives a mixture of diastereomers and enantiomers. The lack of selectivity is due to the reversibility of the reaction and the easy epimerization at the nitro-substituted carbon atom. Existing reviews have hardly mentioned the stereochemistry of the Henry reaction. Recently, Shibasaki has found that the modification of the Henry reaction can control the stereochemistry to give (3-nitro alcohols with high diastereo- and enantio-selectivity.6 In Section 3.3, the progress of the stereoselective Henry reaction and its application to biologically active compounds are discussed. 

Figure 29.1 Biologically active compounds synthesized employing the Henry reaction as a key step.

Compounds containing nitro groups are very usefiil intermediates for the synthesis of natural products and other biologically active molecules. In this respect, p-nitroalka-nols, easily obtained via the nitroaldol (Henry) reaction, provide efficient access to valuable compounds such as 3-amino alcohols. Ramstrom et al. have performed the DKR of several (3-nitroaIkanols combining a Henry reaction and a lipase-catalyzed transesterification (Scheme 57.15). Seeing as the nitroaldol reaction is... 

Fluorine (F) is the second most active chemical element after astatine. It was isolated in 1886 by Henri Moisson in Paris (BriH 1995), and five years later, F. Erhardt in Germany recommended that pregnant women and children should take fluorine pastilles at second dentition. Moreover, F. Erhardt was the first to observe that fluorine fortified dogs dental enamel (Anke 1991). However surprising it is, now as before, the plastic role of fluorine is beyond doubt. Nevertheless, in spite of the availability of a wide class of flu-orous compounds with a pronounced physiological activity, some of the aspects of its biological effects are still not clear. 

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