Tin hydrides water-soluble

A Water Soluble Tin Hydride Tris(3-(2-methoxyethoxy)-propyl)stannane. 

A WATER-SOLUBLE TIN HYDRIDE TRIS[3-(2-METHOXYETHOXY)PROPYL]STANNANE (2,5,13,16-Tetraoxa-9-stannaheptadecane, 9-[3-(2-methoxyethoxy)propyl]-)... 

Finally, although the use of tributyltin hydride is possible in water with or without a detergent as a solubilizing agent [224], noteworthy is the preparation of a water-soluble tin hydride which can be used for the reduction of alkyl halides in phosphate buffer in the presence of a radical initiator. In this way, water-soluble compounds such as unprotected sugars can be used directly without tedious protection/deprotection steps [225]. 

Water-soluble tin hydrides have been synthesized and studied as reducing agents for halides. The work of Breslow and coworkers is based on methoxyethoxypropyl substituents on the SnH moiety (7) in order to afford a water-soluble substrate [48], Another procedure for the reduction of bromides in the presence of a base-soluble dialkyltin(IV) reagent (8) and NaBH4 has been carried out [49]. The use of BujSnH in water solubilized by a suitable detergent has also been reported for the reduction of halides [50]. 

Radical reductions of alkyl halides in water.1 Radical reactions with Bu3SnH are limited to organic solvents, but this tin hydride (1) is sufficiently soluble in water to reduce alkyl bromides or iodides under free-radical conditions in water or in organic solvents. 

The reactions are commonly initiated with AIBN at ca. 80 °C in a solvent such as benzene or toluene, but alkyl halides have also been reduced at -60 °C with tributyltin hydride under sonication conditions.133-134 Some reductions of halides have been carried out by generating the tin hydride in situ from a molar equivalent of the reducing agent [lithium aluminium hydride, sodium borohydride, or poly(methylhydrosiloxane)] and a catalytic amount of organotin hydride, halide, or oxide. Reduction of halides has also been carried out under aqueous conditions, using 4,4 -azobis(4-cyanovaleric acid) (ACVA) as a water-soluble radical initiator.60... 

Water-soluble polyether tin hydride and the bis(2-cardoxyethyl)tin hydroxide allowed reductions and cyclizations to be carried out in water with easy separation from organic soluble products. The latter tin reagent is generated in situ and has not been characterized, but may be a multiplicity of tin oxides and hydroxides. It is soluble in dilute alkali and catalyzes the reduction of alkyl and aryl bromides in the presence of NaBH4 and the water-soluble initiator 4,4 -azobis(4-cyanovaleric acid) (AVCA). 

Clive and Wang have introduced a water-soluble variant of triphenyltin hydride that can be used for the Barton-McCombie reaction. Work-up involves basic or acidic work-up by washing the reaction products with an H2O/THF solution of LiOH or TsOH, respectively, to remove all tin residues. 

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