Tributyl tin hydride

When 1,2,3-selenadiazoles such as 102 are treated with a catalytic amount of tributyl tin hydride and AIBN a vinyl radical species 103 is formed. This radical species can add to electron deficient olefins to give intermediates such as 104 which then undergo intramolecular cyclization to give the dihydroselenophenes such as 105 in moderate to good yields <99TL6293>. 

Tributyl tin hydride [688-73-3] M 291.1, b 76°/0.7mm, 81°/0.9mm, 114 Dissolve in Et20, add quinol (500mg for 300ml), dry over Na2SO4, filter, evaporate and distil under dry N2. It is a clear liquid if dry and decompose very slowly. In the presence of H2O traces of tributyl tin hydroxide are formed in a few days. Store in sealed glass ampoules in small aliquots. It is estimated by reaction with aq NaOH when H2 is liberated. CARE stored samples may be under pressure due to liberated H2. [J Appl Chem 7 366 7957]. 

Sodium triacetoxyborohydride, 283 Other reducing agents Dichlorotris(triphenylphosphine)-ruthenium(II), 107 Dicyclopentadienyldihydrido-zirconium, 108 Samarium(II) iodide, 270 Sodium-Alcohol, 277 Tributyl tin hydride, 316 Reagents which can be used to reduce cyclic ketones to axial (less stable) alcohols... 

Ionization of the substrates to cation radicals is effected by means of tris(4-bro-mophenyl) ammoniumyl hexachloroantimonate (see Section 1.7.10). Subsequent reduction of the cation radicals is accomplished by tributyl tin hydride. For example, 1,1-di(anisyl)ethylene was efficiently (93%) reduced essentially in the time of mixing (less than 1 min). 

Treatment of 6 with a benzene solution of tributyl tin hydride 23 and azobis/.vobutyronitrile (AIBN) 22, introduced slowly with a syringe pump at reflux, provided the tricyclic ketone 7 in 82 % yield. Overall only traces of AIBN as radical initiator and not more than a slight excess of Bu3SnH are needed. 

Tributyl tin hydride reduces selectively bromocyclopropanes without affecting the triple bond (equation 167) The reduction of g m-dibromides is stepwise, which enables convenient access to the monobromoacetylenes and further, via elimination of HBr, to 3-(cyclopropylethynyl)cyclopropene. 

The cyclic (iodomethyl)carbamates 15 can be easily converted into 3-amino-l,2-diol derivatives 17 via iodine displacement with Amberlyst A-26 in the acetate form. In addition, cleavage of the carbon- iodine bond (lithium aluminum hydride or tributyl tin hydride) leads to the trans-2-oxazolidinones 18, which are useful intermediates for the synthesis of 1,2-iyn-amino alcohol systems 199 12. 

The 4-hydroxyl of 8,9-0-isopropylidene derivative 4b has been protected as its 4-t-butyl-dimethyl-silyl ether 4e. Then, the 7-hydroxyl has been converted to its xantate ester 4f, by deprotonation with butyl litium, treatment with carbon disulfide and alkylation with methyl iodide. Deoxygenatiobn of the 7-position has been accomplished by heating with tributyl-tin hydride in xylenes. Then, the cleavage of acetonide and of silyl ether, by heating in 80% acetic acid, followed by hydrogenolysis to remove the benzyl ester, afford 7-deoxy-Neu%Ac-ctMe Im. 

The reduction of (3-hydroxyalkyl selenides to alcohols has been achieved - - - by lithium in ethylamine (Scheme 161, a Scheme 162, a Scheme 163, a Scheme 167) or triphenyl- or tributyl-tin hydride in toluene, with or without AIBN. Most of these reactions proceed through radicals. The reactions involving tin hydrides can be carried out thermally around 120 or photochemically at much lower temperature (0-20 The cleavage of the C—SePh bond is faster than that of the... 

Alkyl halides can be reduced to alkanes by a radical reaction with tributyl tin hydride, (C4H9)3SnH, in the presence of light (hi ) ... 

The trifluoromethyltin halides, (CF3) SnX4 react with trimethyl- or tributyl-tin hydride at -40 °C to give the trialkyltin halide and the corresponding trifluoromethyltin hydrides (CF3)3SnH, (CF3)2SnH2, CF3SnH3, and (CF3)2SnClH as liquids which are unstable at room temperature.18... 

Cyclopropenylium ions 1 were converted into the corresponding cyclopropenes 2 by the addition of hydride ion derived from various hydride sources, such as lithium aluminum hydride,sodium borohydride, borane-amine complex, triethylsilane, and tributyl-tin hydride. Particularly in the case of borohydride reduction of the diphenylcyclo-propenylium ion, the order of reagent addition was quite important. The slow addition of an acetonitrile solution of the cyclopropenylium salt into a solution of the borohydride gave the cyclopropene derivative,whereas the inverse order of addition resulted in quantitative formation of 1,2,4,5-tetraphenylbenzene (see Section 2.1.2.3.), No such precaution of the inverse addition was required in the case of borane-amine reduction of the l-chloro-2,3-diphenyl-cyclopropenylium ion. ... 

In situ synthesis of vinyl stannanes from alkynes [53] A solution of terminal alkyne (1.69 mmol), Pd2dba3 (0.0423 mmol) and lris(furyl)phosphine (P(fu)3, 0.169 mmol) in dry toluene (20 mL) -was stirred and cooled at 0 °C. To this solution was added tributyl tin hydride (1.69 mmol). After 5 min the cooling bath was removed and die reaction mixture stirred for another 2 h at r.t. This vinyl stannane solution can be used directly for Slide couplings. 

As will be elaborated upon later in this chapter, glycosyl fluorides and bromides tend to produce a anomeric radicals while chlorides and iodides show substantially less selectivity. One particular study, involving the reduction of glycosyl bromides under various conditions, was reported by Somsak, et al.,8 and is shown in Scheme 5.1.4. As shown, this study compared a variety of reducing conditions on two 1-bromo-l-cyano glycosides. In both cases, utilizing tributyl tin hydride and a radical initiator, the major products observed resulted from delivery of a hydride with retention of the anomeric configurations. These observations support the preferential formation of a anomeric radicals. 

Indolyl radicals can be generated under standard conditions by reacting 2-bromoindole with tributyl tin hydride. 

The reaction is usually performed at low temperature, typically 20-50 °C, in order to avoid a reaction of the tin complex with the hydroxy groups of the support, as shown by solid-state C CP-MAS NMR. Indeed, it has been shown that tetra-n butyl tin or tributyl tin hydride reacts, above ca. 150 °C with the hydroxy groups of silica, siUca-alumina or alumina with formation of a surface grafted =M-0-Sn(n- 4119)3 fragment and evolution of butane or hydrogen [61, 109-111] (Scheme 18.5). 

A recent synthesis of spiroindolenine derivatives has employed a tandem radical-oxidation sequence [86]. Enamides 137 were subjected to a mixture of tributyl-tin hydride and DLP to produce the corresponding indolenine as a single diastereomer (confirmed from 2D NMR experiments). The mechanism is thought to involve the cyclization of the initial aryl radical to the vinyl group in a 6-endo fashion to generate an a-amidoyl radical which is oxidized by DLP to an acyU-minum ion prior to cyclization at the C-3 position of the indole ring. 

---