Validation, structural discoverie

Synthetic activity associated with the carbonyl-ene reaction is extensive. During the past decade, the trend has been to perform these reactions in the presence of a Lewis acid in an enantioselective fashion. Efforts to find a general catalyst that affords homoallylic alcohols in high yields and enantioselectivities are continual. The synthetic utility of this reaction has been validated by its application to the synthesis of a number of natural products (see Section 10.12.6) and many structurally novel motifs that have found a place in drug discovery vide infra). It is the latter application that has resulted in research efforts aimed at large-scale production of carbonyl-ene adducts. 

The discovery of a cluster of six face-sharing [M6N] octahedra, shown in Figure 3.1-7, in a compound that contained 14 additional Na atoms per cluster, seemed to violate the validity of Miedema s rule, because the central atom refined perfectly as K in the X-ray structure determination. 

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