Platinum functionalized with amides

Reductions of nitronitriles situated to favor interaction are apt to involve both functions (S4,93). Hydrogenation of o-nitrobenzonitrile over either palladium or platinum gave o-aminobenzamide (78), with the amide oxygen transferred from the nitro group (66). On the other hand, l-amino-2-cyanonaphthalene gave the amino amide on reduction over Pt02, but the amino nitrile over palladium (82). 

Hydrogenation of 3 over 10% Pd-on-C led to the expected cyanoamine (4), the amide (5), the lactam (7), as well as 6, in which the nitrile carbon is lost (5. ). The nitrile function is lost before formation of the amine, for 4 resists reduction. A somewhat different distribution is obtained over Pt02, as expected, and accords with the tendency of platinum to produce more intermediate hydroxylamine (82). 

Reduction of amides is an important preparative method for the synthesis of primary amines. Reducing agents used for this purpose include lithium aluminum hydride, sodium borohydride, triphenyl-phosphine (Staudinger reduction), and thiols. In the present case it is important to consider the compatibility of the reduction system with the carboxylic and methanesulfonic acid functions. Platinum and palladium arc often used for catalytic reduction. 

Polyaddition of organosilicon dihydrides, mainly dihydro(poly)siloxanes to dialkenyl-substituted organic compounds also known as hydrosilylation copolymerization, leads to polycarbosiloxanes with functionalized organic segments (359). Platinum-catalyzed polymerization hydrosilylation of a,allyl-substituted bisphenols, imides, or amides leads to the synthesis of block copolymers that are useful thermoplastic elastomers (Scheme 40). 

Carboie lic acids have also been utilised as electrophiles for N-alkylation. Beller reported the reaction of primary or secondary amines with carboxylic acids in the presence of a platinum catalyst and phenylsilane to directly provide the products of reductive amination. The proposed mechanism involves initial amide formation followed by reduction to the amine. A diverse range of functional groups are tolerated, including olefins, alcohols, heterocycles, and esters (Scheme 12.15). 

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