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Tri-n-butyltin hydride is used as a radical reagent in reductive cleavage, radical dehalogenation and intramolecular radical cyclization. It also promotes intramolecular cyclization leading to isoxazolo-benzaulene ring system. Further, it acts as a reducing agent for the conversion of alkyl halides to hydrocarbons. In addition to this, it is used in a veterinary anthelmintic for poultry and an intermediate to make other butyltin compounds.
Reducing agent and source of tributyltin radicals. Widely used for selective reduction of alkyl halides to alkanes by a radical chain mechanism. The reaction is tolerant of a wide range of functionality, including OH and NH, in contrast to polar metal hydride reagents. For reviews, see: Synthesis, 499 (1970); 665 (1987). For a brief feature on uses of this reagent in synthesis, see: Synlett, 173 (2007). For use in the synthesis of deoxy sugars via reductive rearrangement of glycosyl bromides, see: Org. Synth. Coll., 8, 583 (1993). Cyclization of the initially-formed alkyl radical to a suitably positioned double bond may occur. Formation of 5-membered rings is strongly favoured, and ring closure onto an existing ring gives the cis-fused product. See, e.g.: J. Am. Chem. Soc., 108, 5893 (1986):
Intermolecular coupling with electron-deficient alkenes is also effective: Angew. Chem. Int. Ed., 23, 69 (1984); Org. Synth. Coll., 8, 148 (1993). Review: Synthesis, 417 (1988).
Secondary alcohols can be deoxygenated by reduction of their xanthate derivatives: J. Chem. Soc., Perkin 1, 1574 (1975); Org. Synth. Coll., 7, 139 (1990), avoiding the rearrangements encountered with carbocation-based methods.
TBTH also cleaves other C-heteroatom bonds, controlled by the stability of the resulting radical: Nitro-groups at tertiary centers are readily cleaved: Synthesis, 693 (1986). Azides are readily reduced to amines: Synlett, 342 (1991). C-S and C-Se bonds are also cleaved. J. Am. Chem. Soc., 104, 2046 (1982); 112, 4008 (1990); J. Org. Chem., 49, 5206 (1984); 54, 1234 (1989).
Free-radical hydrostannylation of alkenes occurs with TBTH to give alkylstannanes. The reaction is catalyzed by, e.g. Rh complexes: Chem. Lett., 881 (1988), or Pd complexes: Angew. Chem. Int. Ed., 35, 1329 (1996), and refs therein. Syn-addition to alkynes gives vinylstannanes, useful intermediates which undergo electrophilic substitution reactions with retention of configuration. Thus, iodine, NIS and NBS give vinyl halides: J. Org. Chem., 47, 404 (1982); Tetrahedron, 42, 3575 (1986), and alkyllithium compounds exchange to give vinyllithiums: J. Am. Chem. Soc., 99, 7365 (1977). Intramolecular reaction with a double bond has been used in cyclization reactions: Org. Synth. Coll., 8, 381 (1993):
Dialdehydes and keto aldehydes undergo free-radical intramolecular pinacol coupling to give cyclic diols: J. Am. Chem. Soc., 117, 7283 (1995); J. Org. Chem., 63, 6357 (1998).
Arylstannanes have been produced by Pd-catalyzed coupling with aryl iodides: Synlett, 1064 (2000).
For generation and use of tributylstannyllithium, see: Org. Synth. Coll., 8, 562 (1993). Hydroxymethylation of TBTH occurs with LDA and paraformaldehyde. Subsequent reaction with dimethoxymethane gives the hydroxymethyl anion equivalent tributyl[(methoxymethoxy)methyl]stannane: Org. Synth. Coll., 9, 493, 704 (1998).
Zhang, B.; Studer, A. Recent advances in the synthesis of nitrogen heterocycles via radical cascade reactions using isonitriles as radical acceptors. Chem. Soc. Rev. 2015, 44 (11), 3505-3521.
Ghosh, A. K.; Xu, C. X.; Osswald, H. L. Enantioselective synthesis of dioxatriquinane structural motifs for HIV-1 protease inhibitors using a cascade radical cyclization. Tetrahedron Lett. 2015, 56 (23), 3314-3317.
Mentions de danger (UE): H226-H301-H312-H315-H319-H360-H372
Flammable liquid and vapour. Toxic if swallowed. Harmful in contact with skin. Causes skin irritation. Causes serious eye irritation. May damage fertility or the unborn child. Causes damage to organs through prolonged or repeated exposure.
Mentions de prudence: P210-P301+P310a-P303+P361+P353-P305+P351+P338-P405-P501a
Keep away from heat/sparks/open flames/hot surfaces. - No smoking. IF SWALLOWED: Immediately call a POISON CENTER/doctor IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.