Hydrophosphinations aldehydes

Because organophosphorus compounds are important in the chemical industry and in biology, many methods have been developed for their synthesis [1]. This chapter reviews the formation of phosphorus-carbon (P-C) bonds by the metal-catalyzed addition of phosphorus-hydrogen (P-H) bonds to unsaturated substrates, such as alkenes, alkynes, aldehydes, and imines. Section 5.2 covers reactions of P(lll) substrates (hydrophosphination), and Section 5.3 describes P(V) chemistry (hydrophosphorylation, hydrophosphinylation, hydrophosphonylation). Scheme 5-1 shows some examples of these catalytic reactions. 

Abstract In the first part of this mini review a variety of efficient asymmetric catalysis using heterobime-tallic complexes is discussed. Since these complexes function at the same time as both a Lewis acid and a Bronsted base, similar to enzymes, they make possible many catalytic asymmetric reactions such as nitroal-dol, aldol, Michael, Michael-aldol, hydrophosphonyla-tion, hydrophosphination, protonation, epoxide opening, Diels-Alder and epoxi-dation reaction of a, 3-unsaturated ketones. In the second part catalytic asymmetric reactions such as cya-nosilylations of aldehydes... 

Simultaneous publication of the iminium ion catalysed hydrophosphination of a,p-unsaturated aldehydes by Melchiorre and Cordova showed diarylprolinol silyl ether 55 was effective in the conjugate addition of diphenylphosphine 74 [117, 118], Direct transformation of the products allowed for one-pot methods for the preparation of P-phosphine alcohols 75 (72-85% yield 90-98% ee), P-phosphine oxide acids 76 (65% yield 92% ee) and 3-amino phosphines 77 (71% yield 87% ee) (Scheme 34). These reports represent the first examples of the addition of P-centred nucleophiles and the resulting highly functionalised products may well have further use in asymmetric catalysis. 

Organolanthanide complexes are known to be highly active catalysts for a variety of organic transformations, which can be either intramolecular or intermolecular in character. Successful intramolecular transformations include hydroelementation processes, which is the addition of a H-E (E = N, O, P, Si, S, H) bond across unsaturated C-C bonds, such as hydroamination, hydroalkoxylation, and hydrophosphination. Intermolecular transformations include a series of asymmetric syntheses, the amidation of aldehydes with amines, Tishchenko reaction, addition of amines to nitriles, aUcyne dimerization, and guanylation of terminal aUcynes, amines, and phosphines with carbodiimides. 

Interest has also eontinued in addition reactions of P-H bonds to carbonyl groups. A kinetic study of the reaction of phosphine with formaldehyde, including the eflfeets of eatalysts, has appeared. A study of the hydrophosphination of phenolie aldehydes with diphenylphosphine has demonstrated the initial reversible formation of a-phosphinocarbinols (103) that rearrange to form the phosphine oxides (104). Treatment of the latter with iodomethane, followed by reduction with lithium aluminium hydride, affords the related phosphines (105). A mixture of diastereoisomers of the bis(phosphatrioxaadamantyl)propane (106) is formed on treatment of 1,3-diphosphinopropane with acetylacetone in the presence of aeid. RecrystaUisation from ethanol gives a mixture enriched in the rac-isomer (90% 10%). ... 

In addition, Cordova et al. have developed highly enantioselective organocatalytic hydrophosphination reactions of a,p-unsaturated aldehydes. These novel reactions were catalysed by protected chiral diarylprolinol derivatives... 

Scheme 1.73 Hydrophosphinations of a,P-unsaturated aldehydes catalysed by sily-lated diarylprolinols.

Ibrahem I, Rios R, Vesely J, Hammar P, Eriksson L, Himo F, Cdrdova A. Enantioselective organocatalytic hydrophosphination of a, p-unsaturated aldehydes. Angew. Chem. Int. Ed. 2007 46 4507 510. 

Scheme 8.82 BHs-mediated transition-metal-free hydrophosphination of aldehydes and imines...

Carlone A, Bartoli G, Bosco M, Sambri L, Melchiorre P (2007) Organocatalytic asymmetric hydrophosphination of a,J -unsaturated aldehydes. Angew Chem Int Ed 46 4504-4506... 

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