Carbonyl heterofunctionalization

Abstract Aldehydes obtained from olefins under hydroformylation conditions can be converted to more complex reaction products in one-pot reaction sequences. These involve heterofunctionalization of aldehydes to form acetals, aminals, imines and enamines, including reduction products of the latter in an overall hydroaminomethylation. Furthermore, numerous conversions of oxo aldehydes with additional C.C-bond formation are conceivable such as aldol reactions, allylations, carbonyl olefinations, ene reactions and electrophilic aromatic substitutions, including Fischer indole syntheses. 

Accessing enantioenriched carbonyl compounds possessing heterofunctionalized a-carbon stereocenters is a very challenging task in organic synthesis, especially in... 

Conjugate additions of enamines to ot,p-unsaturated carbonyl or nitro compounds belong to the most commonly applied and useful organocatalytic C-C bondforming reactions (JS5,143-150). As already mentioned above, enamine-catalyzed conjugate additions are often used in combination with a-heterofunctionalizations. These combined examples will be described in more detail in Sect. 2.6. 

Guillena G, Ramon DJ (2006) Enantioselective a-Heterofunctionalization of Carbonyl Compounds Organocatalysis Is the Simplest Approach. Tetrahedron Asymmetry 17 1465... 

Reviews cover transition-metal-catalysed enantioselective a-heterofunctionalization of carbonyl compounds (103 references)," and organocatalysed enantioselective a-hetero-functionalization from 2006 to 2009, demonstrating straightforward syntheses of useful a-amino acids and alcohols, epoxides, 1,2-diols, and a-sulfenylated, a-selenenylated, and a-halogenated carbonyl derivatives." ... 

Transition-metal catalysed enantio-selective a-heterofunctionalization of carbonyl compounds has been reviewed. The kinetics and mechanism of iodination of substituted hydroxyacetophenones by iodine monochloride (ICl) in acetic acid/water... 

Scheme 22.5 (S)-Proline-catalyzed asymmetric heterofunctionalization of carbonyl compounds in an IL medium.

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. 

Only in the last decades, the use of organic molecules as catalysts has emerged as an important area of research with spectacular numbers of contributions in every journal issue. The aim of this chapter is to cover some important achievements in the enantioselective a-heterofunctionalization of carbonyl compounds using the organocatalyst strategy, in which a new carbon-heteroatom bond is... 

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