Organostannane halides

Ionomers have been synthesized from reaction of tin II and tin IV metal halides and organostannane halides through reaction with an ethylene-acrylic acid copolymer. Mass spectral, infrared spectral, and elemental analysis results are consistent with the formation of tin-containing ionomers. The products all exhibit "ionomer-like" properties and soften below 150 C, many softening below 50 C. 

Other Instances have been reported relating biological response with state and eiq>loyed solvent. For Instance there exists a direct correlation between the tendency toward Inhibition by solid samples of (polyethylenelmlne modified through condensation with organostannane halides) and results employing the same solvents dis solved In DMSO (3). 

The product is a yellow or yellowish brown powder insoluble in all common solvents. It degrades upon prolonged stirring with NaOH solution hence the reaction should be terminated as soon as product formation is complete. It does not melt but decomposes above 250°. Elemental analysis shows approximately 7-11% Ti, which corresponds to 0.5-0.7 (C3H )2 Ti unit per glucose subunit in the amylose. (one (0511 )2 Ti unit per glucose subunit would be 14% Ti, two would be 19% Ti and three would be 21%. Titanocene dichloride itself is 27.1% Ti). In our previous studies of the reaction of titanocene dichloride with dextran approximately 1 1 stoichiometry was also observed. For similar reactions with organostannane halides yields of 80% and approximately 1 1 stoichiometry was also observed. Apparently steric factors limit the number of titanocene units that can bind, since an excess of titanocene is present. y... 

CHEMICAL MODIFICATION OF POLYSACCHARIDES - MODIFICATION OF DEXTRAN THROUGH INTERFACIAL CONDENSATION WITH ORGANOSTANNANE HALIDES... 

Thus, modification is general for a variety of organostannane halides and is dependent on the nature of the stannane. 

MODIFICATION OF DEXTRAN THROUGH REACTION WITH ORGANOSTANNANE HALIDES AS A FUNCTION OF REACTION SYSTEM - A MODEL FOR POLYSACCHARIDE MODIFICATION... 

The major purpose of this research involves the evaluation of a number of potential condensation systems for the purpose of determining which systems might be useful in the modification of various polysaccharides through condensation with organostannane halides. 

There are commercially available a wide number of R.SnX. confounds including R = methyl, propyl, butyl, hexylf cyclohexyl, octyl, benzyl, phenyl, ethyl, and X = F,Cl,Br permitting trends to be established with regard to the steric and electronic nature of the employed organostannane. The use of dibutyltin diohloride was emphasized since it has been successfully condensed with diols and with polyvinyl alcohol and it is the least expensive organostannane halide. 

Aryl halides react with a wide variety of aryl-, alkenyl- and alkylstan-nanes[548-550]. Coupling of an aryl tritlate with an arylstannane is a good preparative method for diaryls such as 688. The coupling of alkenylstannanes with alkenyl halides proceeds stereospecifically to give conjugated dienes 689. The allylstannane 690 is used for allylation[397,546,551-553]. Aryl and enol triflates react with organostannanes smoothly in the presence of LiCl[554]. 

The intramolecular insertion of an internal alkyne into an aryl or alkenyl halide 727 generates aryl- or alkenylpalladium as an intermediate, which is trapped with an organozinc or organostannane to give 728. Overall cis addition to the alkyne takes place[595,596]. The reaction of the alkenylstannane 730 with the 2-bromomethylfuran 729 is used for the introduction of a prenyl group[597]. 

Procedures for the synthesis of ketones based on coupling of organostannanes with acyl halides have also been developed.211 The catalytic cycle is similar to that involved in coupling with aryl halides. The scope of compounds to which the reaction is applicable includes tetra-u-butylstannane. This example indicates that the reductive elimination step competes successfully with (3-elimination. 

Coupling of organostannanes with halides in a carbon monoxide atmosphere leads to ketones by incorporation of a carbonylation step.249 The catalytic cycle is similar to that involved in the coupling of alkyl or aryl halides. These reactions involve Reactions involving a migration of one of the organic substituents to the carbonyl carbon, followed by... 

The main method for the preparation of different types of organostannanes is the ancient Wilrtz reaction between triorganotin halides or diorganotindihalides. Reactions proceed with or without solvent. Usual solvents are benzene, toluene, xylene, diethyl ether and ethanol. Occasionally hquid ammonia is also used. The preferred metals for this reaction are sodium and lithium. In the case of triorganotin halides, the reaction leads to symmetric hexaorganoditin compounds72 ... 

Like most aryl halides, furyl halides and furyl triflates have been coupled with a variety of organostannanes including alkenyl, aryl, and heteroaryl stannanes in the presence of catalytic palladium. Carbamoylstannane 66 was prepared by treating lithiated piperidine with carbon monoxide and tributyltin chloride sequentially. The Stille reaction of 66 and 3-bromofuran then gave rise to amide 67 [61]. In another example, lithiation of 4,4-dimethyl-2-oxazoline followed by quenching with MesSnCl resulted in 2-(tributylstannyl)-4,4-dimethyl-2-oxazoline (68) in 70-80% yield [62], Subsequent Stille reaction of 68 with 3-bromofuran afforded 2-(3 -furyl)-4,4-dimethyl-2-oxazoline (69). 

Palladium-catalyzed cross-coupling reaction of organostannanes with organic halides, triflates, etc. For the catalytic cycle, see Kumada coupling on page 345. 

We note that while tin reagents have often been employed for the organoboron halides/ the use of organostannanes as starting materials can also be applied to the synthesis of heavier group 13 derivatives. In the context of polyfunc-tional Lewis acid chemistry, this type of reaction has been employed for the preparation of ort/ o-phenylene aluminum derivatives. Thus, the reaction of 1,2-bis(trimethylstannyl)benzene 7 with dimethylaluminum chloride, methylaluminum dichloride or aluminum trichloride affords l,2-bis(dimethylaluminum)phenylene 37, l,2-bis(chloro(methyl)aluminum)phenylene 38 and 1,2-bis(dichloroalumi-num)phenylene 39, respectively (Scheme 16). Unfortunately, these compounds could not be crystallized and their identities have been inferred from NMR data only. In the case of 39, the aluminum derivative could not be separated from trimethyltin chloride with which it reportedly forms a polymeric ion pair consisting of trimethylstannyl cations and bis(trichloroaluminate) anions 40. 

Some examples of Pd-catalyzed coupling of organostannanes with halides and triflates are included in Scheme 8.10... 

Synthesis of a-fluoro-ot, -unsaturated ketones via palladium-catalyzed crosscoupling reaction of 1-fluorovinyl halides (79) with organostannanes (80)... 

C. Chen, K. Wilcoxen, C.Q. Fluang, N. Strack, J.R. McCarthy, New methods for the synthesis of fluoro olefins via the palladium catalyzed cross-coupling reaction of 1-fluorovinyl halides with organoboranes and organostannanes, J. Fluor. Chem. 101 (2000) 285-290. 

In 2001, Nolan described the palladium/imidazoilium salt-catalyzed coupling of aryl halides with hypervalent organostannanes.The imidazolium salt 36 in combination with Pd(OAc)2 and TBAF was found to be most effective for the cross-coupling of aryl bromides and electron-deficient aryl chlorides with aryl and vinyl stannanes. 

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