Organic Synthesis Using Organoboron Compounds

Organic Synthesis Using Organoboron Compounds 9.05.3.1 Protodeboronation, Oxidation, Halodeboronation, Amination... 

The traditional synthesis of organoboron compounds from organic halides is based on the reaction of trialkyl borates with Grignard or lithium reagents. However, the cross-coupling reaction of diboron solves the difficulties associated with the use of Mg/Li compounds. The cross-coupling reaction of diborons... 

Much attention has recently been focused on organoboronic acids and their esters because of their practical usefulness for synthetic organic reactions including asymmetric synthesis, combinatorial synthesis, and polymer synthesis [1, 3, 7-9], molecular recognition such as host-guest compounds [10], and neutron capture therapy in treatment of malignant melanoma and brain tumor ]11]. New synthetic procedures reviewed in this article wiU serve to find further appHcations of organoboron compounds. 

The use of solid supported, recyclable catalysts, is a well-assessed technique in classic organic chemistry, and many exhaustive reviews dealing with this subject are available [105, 115]. The use of solid supported catalysts for library synthesis in solution has also been reported. Among others, Kobayashi et al. presented the use of a new supported scandium catalyst for 3CC reactions leading to solution libraries of amino ketones, esters, and nitriles (24-member model discrete library) [116], or to quinolines (15-member model discrete library) [117], and Jang [118] presented a polymer bound Pd-catalyzed Suzuki coupling of organoboron compounds with halides and triflates. This area was also briefly reviewed recently [119]. 

Although clearly of use in the synthesis of certain alkylboron compounds, particularly tri-n-alkylboranes and alkylboron hydrides, the hydroboration reaction (developed mainly by H. C. Brown) is of considerable significance in synthetic organic chemistry, as the resulting organoboron compound can be used (without being isolated) as an intermediate in the conversion of olefins or acetylenes into other hydrocarbons (parafi or olefins), alcohols, aldehydes, ketones, carboxylic acids or amines. 

General. - There are many papers in which organoboron compounds are used as reagents in organic synthesis. These are beyond the scope of this review and they are not included here although mention has been made of one or two interesting examples. 

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