Carbonyl compounds, addition reactions overview

Several reviews on allylboron compoimds and odier allylmetal reagents and their additions to carbonyl compoimds and imines have appeared [1-6], including two excellent chapters in a book from Wiley-VCH [1,2]. Accordingly, diis chapter does not aim to provide a comprehensive accoimt on die chemistry of allylboronates, but presents instead an overview of die main preparative methods for allylboronates, with particular focus on advances reported in die past five years, and on several recent synthetic applications such as the Lewis add-catalyzed additions to carbonyl compounds and tandem allylation reactions. 

Abstract The use of organoaluminum-based Lewis acids (A1R X3 R = alkyl, alkynyl, X = halide or pseudohalide) in the period 2000 to mid-2011 is overviewed with a focus on (1) stoichiometric reactions in which one of the organoaluminum substituents is transferred to the substrate (e.g., the opening of epoxides, 1,2-additions to carbonyl compounds, coupling with C-X, and Reissert chemistry) and (2) asymmetric, often catalytic, reactions promoted by Lewis acid catalysts derived from organoaluminum species (e.g., use of auxiliaries with alanes, Diels-Alder, and related cycloaddition reactions, additions to aldehydes and ketones, and skeletal rearrangement reactions). 

Cyclopropanation reactions are one set in an array of C-C bond-forming transformations attributable to metal carbenes (Scheme 5.1) and are often mistakenly referred to by the nonspecific term carbenoid. Both cyclopropanation and cyclopropenation reactions, as well as the related aromatic cycloaddition process, occur by addition. Ylide formation is an association transformation, and insertion requires no further definition. All of these reactions occur with diazo compounds, preferably those with at least one attached carbonyl group. Several general reviews of diazo compounds and their reactions have been published recently and serve as valuable references to this rapidly expanding field [7-10]. The book by Doyle, McKervey, and Ye [7] provides an intensive and thorough overview of the field through 19% and part of 1997. 

The reaction of 2,3,4,5-tetrakis(trifluoromethyl)(yclopenta-2,4-dien-l-one with tertiary phosphines results in nucleophilic attack by the phosphine at carbonyl ojgrgen to form zwitterionic adducts. Nucleophilic attack at carbonyl ojgrgen is also implicated in a phosphine-mediated addition of 1,2-dicarbonyl compounds to nitroso-electrophiles. The diphosphine l,l-bis(diphenylphosphino)methane has been shown to undergo redox reactions with o-quinones, forming phosphine oxides of type (104). An overview of the reactions of HNO (azanone) with metal porphyrins includes reference to O-atom abstraction by phosphines from HNO to form nitrite. ... 

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