Triorganotin hydrides

From Triorganotin Hydrides to Triorganostannyl-Transition Metal... 

The reaction between triorganotin hydrides and organic halides is known since 1957 68). Analogous reactions have been described for chiral triorganosilicon69) and -germanium 70) hydrides, which are stereoselective. It is well known that they proceed via the triorganometal radical, which can also be formed photochemically from metallated ketones 71). 

Triorganotin hydrides do react with HMn(CO)5 to give Mn2(CO)10 and the expected (triorganostannyl)pentacarbonyl manganese80. In THF, only these two compounds are formed. In benzene, in addition to these two products, the hexa-organoditin and some starting product are found in the reaction mixture. 

A series of nonracemic triorganotin hydrides (37-39) was prepared by reduction of racemic halostannane precursors with a chiral alkoxy hydride reagent (Scheme 14)21. 

The first optically active organotin, where the metal atom is the only chiral center, was synthesized132 using tetra-p-anisyltin as starting material. A racemic triorganotin hydride was first prepared by the sequence of reactions... 

In the case of triorganotin hydrides, the reaction with R3SnX (where X = OAc, Cl, I, CN) requires the presence of triethylamine as a catalyst99. 

Hydrostannation refers to the addition of triorganotin hydride to different types of alkenes or alkynes, in the presence of catalysts, making possible the preparation of various types of stannylalkanes or stannylalkenes130. 

Reactions of triorganotin hydrides with amines resulted in the formation of the corresponding ditin species according to equation 4454- 56. 

TABLE 43. Selected structural and NMR data for tetraorganotin compounds and triorganotin hydrides containing a potential C,N- or C,P-chelating ligand... 

SCHEME 11. Triorganotin hydrides containing one C,N-chelating ligand... 

Triorganotin hydrides are common reductants in a large number of organic and organo-metallic syntheses. In many cases these reductions proceed by a normal radical reaction pathway. However, ionic reductions using tin hydrides also occur, but they were only sparsely investigated. Studies of ionic reduction processes with tin hydrides by using Sn NMR are found elsewhere . 

Organotin hydrides can undergo either heterolytic or homolytic reactions. Reactions with carboxylic acids and with R)SnX (X = OR, NR2, or other nucleophilic groups) are considered to be heterolytic reactions. Other heterolytic reactions of triorganotin hydrides are shown in Scheme 12. 

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