Reactions of alkyltins

Three papers have appeared in which tetramethyltin is used as a methyl-transfer agent one involves an aryl triflate [151], one a vinyl triflate [152], and the third a sextuple coupling [153] (conversion of three PC12 units in hexachlorocyclotriphosphazene into PMe2 units). 

Falck and co-workers [154] have studied reactions of alkoxyalkyltributyltins with acid chlorides, and in one case studied the stereochemistry of the reaction, which proceeded with 98% retention. Cyclopropyl transfer via reaction with a nucleoside bromide has also been carried out [155]. The traditional catalysts [Pd(PPh3)4 or PdCl2(PPh )2] were used, but with various additives (LiCl, CuCN). 

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Chemical reactions of alkyltin compounds which occur by way of radical cations are described in Section 5.3.7. The radical cations themselves have been examined in frozen matrices mainly by the technique of ESR spectroscopy, and in the gas phase by mass spectrometry. 

TABLE 2. Pd-Catalyzed Cross-Coupling Reactions of Alkyltins with Alkenyl and Aryl Electrophiles... 

Some reactions of alkyltin compounds are summarized in Fig. 4.5. This... 

The stoichiometric reactions of alkyltin chlorides with sodium alkoxides generally yield the aUcyltin alkoxide derivatives. The method was finally extended to the preparation of Bu Sn(OR)3, in spite of earlier unsuccessful attempts ... 

The reactions of tetraorganotins with ICl, EBr, and CICN have been investigated as synthetic routes to aryl cyanides (111) and alkyltin bromides and chlorides (112,113). 

Mixed alkyltin hydrides are relatively difficult to prepare. Nevertheless, a convenient synthesis starts from the reaction of SnBr4 or SnLt with 2,4,6-tri-f -butylphenyllithium 105 ... 

Alkylhalotin hydrides are prepared by reaction of an alkyltin hydride with either an alkyltin halide with the same alkyl groups232 or with hydrogen halides233, e.g. ... 

Redistribution reactions are considered as quite important for the preparation of alkyltin halides having mainly identical alkyl groups. Actually, the redistribution reactions are halogenation reactions of organotin halides by SnX4 (X = F, Cl, Br, I). 

Nucleophiles react by attack at the tin center. The reaction of the trialkynyltin compounds RSnfC CR T with primary or secondary alcohols gives the alkyltin trialkoxides, RSn(ORz)3, and controlled hydrolysis gives the closo-clusters [(RSn)12(/730)i4(/r20H)6](0H)2 (Equation (86)).24 The spacer-bridged hexaalkynyldistannanes are... 

The kinetics and mechanism of the phosphorus-catalysed dimerization of acrylonitrile to give 1,4-dicyanobut-l-ene and 2,4-dicyanobut-l-ene have been studied.114 The reactions of aryhminodimagnesium (138) with //-substituted p-cyanobenzophenones, l-cyano-9-fluorenenone, o-, m-, and p-dicyanobcnzcnes, and o-, m-, and p-nitrobenzonitriles have been examined.115 The effect of pressure on the reaction of 3 -methyl- l-(4-tolyl)triazene (139) and benzoic acid in chloroform and acetonitrile has been studied.116 The effect of acids on the rate of urethane formation from alcohols and isocyanates in the presence of alkyltin carboxylates has been examined.117 A Hammett a value has been reported for the amidine group N=CHNMe2 and used for the prediction of the basicity of sites in bifunctional amidines.118... 

Similar reaction of a bifunctional alkyltin reagent with the enol silyl ether of a cyclic ketone gives rise to fused ring systems (cf. 13, 118 15, 237). 

Mercaptides are unchallenged as the ligand of choice for the other entities bonded to the tin, but carboxylates can also be used. Whereas a variety of mercaptans are used, the thioglycolic acid derivatives remain the laigest single mercaptan. Dibutyltin bis(isooctyl thioglycolate) [25168-24-5] and butyltin tris(isooctyl thioglycolate) [25852-704] are two common examples. These materials are produced by the reaction of the appropriate alkyltin chloride or oxide, and the mercaptan. 

SnCU is also the principal source of alkyltin chlorides, R SnCl4 [51]. Allyltrialkyl-tin reagents react with SnCU to produce allyltrichlorotin species through an Se2 pathway (Eq. 32) [52-56], Allyltrimethylsilanes react with SnCU to produce the corresponding allyltrichlorotin (Eq. 33) [57]. Silyl enol ethers react with SnCU to give a-tri-chlorotin ketones (Eq. 34) [58]. Transmetalation or metathesis reactions of this type... 

Coupling reactions of alkylzinc and alkyltin reagents with alkenyl halides are catalyzed efficiently by Pd and, in some cases, by Ni complexes. 

Similarly the polarity of the Sn5+-X5 bond enhances the nucleophilicity of X in substitution reactions.6 A simple example is the reaction of bis(tributyltin) oxide with a dialkyl carbonate, which gives the alkyltin carbonate, which then eliminates C()2 by the reverse of the above reaction to provide the easiest route to tributyltin alkoxides (see Section 14.1.1). 

Reactions of organotin compounds with Lewis acids by have been carried out particularly with mercury(II) salts in mechanistic studies, with SnCl4 (the Kocheshkov reaction) for the preparation of alkyltin chlorides, and with lead tetraacetate. 

The opposite polarity in the organotin reagent R3Sn5+X5 can be exploited in, for example, the reaction of a tin alkoxide with an vinyl ester,83 the addition of an alkoxy- or amino-tin compound to a ketene,84 the reaction of a silyl enolate with a tin chloride,85 or the addition of an alkyltin hydride under non-radical conditions to an a,P-unsaturated carbonyl compound.86... 

A similar reaction of a stannonic acid with triethanolamine, or of an alkyltin trihalide and triethanolamine in the presence of sodium methoxide (equation 14-50) gives stanna-tranes,100 which have attracted some attention because of their interesting structures and their relation to the silatranes which have purported physiological properties. 

The field of organotin chemistry has a long history that started as early as 1849, when Frankland isolated a specimen of diethyltin diiodide (1,2). In 1852, Lowich independently reported on the reaction of alkyl halides with a tin-sodium alloy giving alkyltin compounds (3). This last publication is usually considered to represent the beginning of organotin chemistry. 

Further reaction of the organotin(II) chloride 14 with 4-tolyl-, neopen-tyl-, or neophyllithium affords the unique corresponding mixed aryl—alkyltin(II) compounds 15,16, and 17 respectively [Eq. (3)] (85). 

Trialkyltin hydrides are prepared by the reduction of trialkylhalostannanes with lithium aluminum hydride or the reaction of poly(methylhydrosiloxane) with bis(tri-alkyltin)oxides (eq (138)) [133]. Starting materials for the latter preparation are obtained by the hydrolysis of trialkylchlorostannanes with sodium hydroxide followed by the further treatment of the resulting trialkylhydroxystannanes with sodium metal. 

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