Vinyltins

Trimethyltin hydride has been shown to add to trimethylvinyltin, and triethyltin hydride to triethylvinyltin, to give both the 1,1- and the 1,2-distannylethanes, whereas triphenyltin hydride reacts with triphenyl vinyltin to give only the 1,2-adduct (180). 

Vinylic halides can also be coupled " with Zn—NiCli, with vinyltin reagents and a palladium catalyst, and with n-BuLi in ether in the presence of MnCl2. 

Arylation and Alkylation of Alkenes by Vinyltin Compounds The Stale Reaction... 

Other organometallic compounds add to isocyanates. Vinyltin reagents lead to conjugated amides. ... 

Arylation and alkylation of alkenes by vinyltin compounds (the Stille... 

It is commonly known that vinyltin compounds undergo no free-radical polymerization and do not readily copolymerize with various vinyl monomers which can be attributed to their inhibiting effect towards radical reactions48,79. ... 

Free-radical copolymerization of trimethyl- or tributylvinyltin with styrene or methyl methacrylate results in low ( 10%) yield of copolymer. Moreover, both the reaction rate and viscosity decrease considerably with higher vinyltin content in the starting mixture 49). These findings imply that organotin monomers tend to inhibit free-radical copolymerization. 

However, vinyltin monomers are readily polymerized or copolymerized with butyllithium at 0 and 20 °C respectively by an anionic mechanism51). 

Vinyltin compounds are very important in organic synthesis, since the vinyl moiety can be readily transferred to carbon in the (palladium-catalyzed) Stille reaction. The transfer is stereospecific, and the geometry of the vinyltin moiety can be easily checked using proton and carbon-13 NMR via the coupling satellites. 

By regiospecific [4+2] cycloadditions of functional alkenyltin derivatives with dienes such as 1,3-butadiene, 2,3-dimethyl-l,3-butadiene or 1-substituted 1,3-butadienes, polyfunctional cyclic vinyltin compounds 80 are obtained. 

Fukuyama employed a vinyltin derivative in the carbonylation of 3-carbomethoxymethyl-2-iodoindole to afford 320 [176]. Buchwald effected the carbonylation of 4-iodoindole 321 to give lactam 322 [136], and a similar carbonylation reaction on 4-iodoindole malonate 125 gives ketone 323 in 68% yield. 

In the more prolific aspect of the Stille couplings involving a pyrimidine fragment, pyrimidinyl halides or triflates have been coupled with a variety of stannanes. When there is only one reactive halide on the pyrimidine ring, the reaction outcome is straightforward with no regiochemical concern. The simpler stannanes are vinyl stannanes [35-37]. More complicated variants include stannylquinones [38] and l-(trialkylsilyloxy)vinyltin [39] as illustrated by the synthesis of 66. 

Coupling of vinyl halides with vinyltin reagents. This cross-coupling can be effected at room temperature in DMF in the presence of (CH,CN)2PdCl, or CLPd[P(C6H5),]2. Pure (E,E)-, (E,Z)-, (Z,E)-, or (Z,Z)-1,3 dienes can be prepared by this reaction, since the geometry of each partner is retained. The reaction tolerates many functional groups. 

Macrolides can be obtained in satisfactory yield by a Pd(0)-catalzed intramolecular coupling of an ester with vinyl triflate and vinyltin groups at the two ends (cf., 12,469-470). This cyclization is insensitive to the ring size the yield is 56-57% in the cyclization of 1 to form 12- to 15-membered rings.3... 

The fluorodestannylation with XeF2 takes place rapidly at room temperature in the presence of 2,6-di-t-butyl-4-methylpyridine, fast enough for introducing the short-lived 1SF isotope, and is thought to involve the initial formation of triflic hypofluoride, F3CSO3F, and then its adduct with the vinyltin compound (Equations (74)-(76)).228... 

The lithiated compound was obtained via the vinyltin derivative which was first converted into the vinyl iodide before doing the halogen-metal exchange, Fig. (30 and 31). 

Table 9. Fluorination of Vinyltin Compounds with F-Teda BF4 (6) in Acetonitrile88...

This general procedure has been used to prepare x3 a large number of vinyltin compounds, including ... 

---