Alpha-Heteroatom Functionalization of Carbonyl Compounds

The methodology known as direct a-heterofunctionalization of carbonyl compounds was comprehensively reviewed in 2006 [1] and therefore only the most recent developments [2] in this research area since then are considered in this section. These will be presented by the reaction that led to the formation of the new carbon-heteroatom bond, excluding of those in which the hybridization of the previously functionalized carbonyl compound is modified. 

Comprehensive Enantioselective Organocatalysis Catalysts, Reactions, and Applications, First Edition. 

On the other hand, non-covalent interactions [4] have been proposed to justify the stereochemical control of the process when Br0nsted bases or acids and phase-transfer catalysts [5] are used to promote these types of reactions, especially when 1,3-dicarbonyl compounds [6] were used as substrates. While the formation of chiral ion-pairs governs the heteroatom approach for basic catalysts, the formation of hydrogen bonds is responsible in the case of chiral Br0nsted acids. In both cases, the effective shielding of one face of the nucleophile by the chiral catalyst determines the formation of the optically active product. 

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