Trimethyltin reaction

Tnmethyl(trifluororaethyl)tin can also be prepared via in situ formation and capture of tnfluorometbide by trimethyltin chlonde [13, 14] (equation 9) This tin analogue has been used as a precursor for difluorocarbene either by thermal decomposition or by reaction with sodium iodide m 1,2-dimethoxyethane This carbene generation procedure has been used to study difluorocarbene selectivity with steroidal olefins [75] (equation 10). 

The phosphonium salt method works best with nucleophilic olefins [//, 12, 16, 17, 18, 19] (Table 1 and equations 1-3) and has been used m mechanistically important studies of difluorocarbene additions to norbornadienes [20 21, 22, 23] that provided the first example of a concerted homo-l,4-addition (equation 4) A recent modification uses catalytic 1,4,7,10,13,16 hexaoxacyclooctadecane (18-crown-6) to shorten reaction times and increase yields with less nucleophilic olefins [12] (Table 1) Neither procedure, however, compares with the use of phenyl(tri-f1uoromethyl)mercury or (trifluoromethyl)trimethyltin reagents [efficient reactions with less nucleophilic olefins (equations 3 and 5) and cyclic dienes [24, 25] (equations 6 and 7)... 

The corresponding reaction with PlnSnM proceeds with complete inversion regardless of addition mode (equation 21). In this case, radical reactions appear unimportant. Displacement of the tosylate by a trimethyltin cuprate was also found to take place by inversion. 

Finally, Podoplelov and coworkers41 have prepared trimethyltin hydride and benzyltrimethyltin labelled with tin-117 from a tin sample enriched to 92% in 117Sn. The photochemical reaction between dibenzyl ketone and trimethyltin-117 hydride was used to investigate the chemically induced dynamic nuclear polarization of tin-containing radicals. 

The methyl-[14C]-dimethyltin chloride was used to compare the performance of packed and megabore capillary columns in a gas chromatographic analysis for separating mixtures of a carbon-14 labelled trimethyllead chloride, tetramethyltin, dimethyltin dichloride and methyltin trichloride. The megabore column was able to separate all four methyltin compounds quickly, i.e., before the tetramethyltin decomposed into trimethyltin chloride and dimethyltin dichloride (equation 47), a reaction which did occur on the packed columns. Thus, the megabore column enabled the determination of the precise distribution of the various methyltin compounds in an environmental sample. The packed columns, on the other hand, could not separate dimethyltin dichloride and the methyltin trichloride and allowed significant decomposition of the tetramethyltin during the 15 minutes the analysis required. 

The various tetraalkyltin compounds were then identified and quantitated by GC MS and gas chromatography-atomic absorption analyses. The results indicated that tin(II) chloride in the simulated sea water was converted into methyltin trichloride and dimethyltin dichloride. The tin(IV) chloride, on the other hand, only formed methyltin trichloride. No trace of trimethyltin chloride was found from either tin(II) or tin(IV). The maximum amount of methyltin trichloride was formed near pH = 6 and at a salinity of 28%. The rate expression for the reaction is... 

CD3(CH3)3Sn by reacting an excess of trideuteromethylmagnesium iodide with tin tetrachloride, methyltin tribromide, dimethyltin dibromide and trimethyltin bromide, respectively. In each reaction, CD3 groups replace all the halogen atoms on the tin forming the various deuterated tetramethyltin compounds. Equation 51 illustrates these reactions using methyltin tribromide. 

This catalytic reaction was believed to proceed analogously to those with phenylboronic acids (Scheme 49) 137 137a Transmetallation of the arylstannane with the cationic rhodium complex generated the rhodium aryl species a and trimethyltin tetrafluoroborate. Conjugate addition generated rhodium enolate b, which subsequently reacted with... 

A third method of estimating solvent basicity is provided by the donor number concept 14 ). The donor number of a solvent is the enthalpy of reaction, measured in kcal per mole, between the solvent and a Lewis add such as antimony (V) chloride. (Other Lewis acids, such as iodine or trimethyltin chloride, may be used, but the scale most often reported is that for SbCl5.) Available values for the SbCls donor number have been included in Table 1. Plots of the Walden product versus solvent basicity (A//SbC1 ) for several solvents are shown for lithium, sodium, and potassium ions in Fig. 10 and for the tetraalkylammon-... 

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. 

The enantioselective addition of the amino organolithium reagents consists of two stereo-controlled reactions, the asymmetric deprotonation (equation 14) and the following addition to electrophiles. The stereochemical course of the addition depends on the electrophile E. In the cases where heterocyclic enone or a,-unsaturated lactones are the electrophiles (entries 5-7), the addition proceeds with retention of configuration. In contrast, with the other electrophiles in Table 10 and trimethyltin chloride in equation 15, the addition proceeds with inversion of configuration. In the addition which proceeds with retention of configuration, a pre-complexation between the electrophiles and lithium may be involved (equation 16). 

Trimethyltin chloride can be purchased from Strem Chemicals, Inc. or prepared by the reaction of tetramethyltin with tin tetrachloride as follows To a 100-mL, round-bottomed flask, equipped with a magnetic stirring bar, and a septum, and a gas Inlet connected to a static argon atmosphere, containing 41.2 g (0.230 mol) of tetramethyltin cooled to -20°C with a dry ice/carbon tetrachloride slurry, is added 9.0 mL (0.0769 mol) of tin tetrachloride at a slow dropwise rate. After the addition is complete, the... 

The progress of the reaction is conveniently monitored by gas chromatography on a 1/8" x 6 column packed with 6X SP-2100 on Supelcoport, 80-100 mesh, operated at 50°C for 4 min, then heated at 15°C/min to 250°C. The relative retention times are 4.0 min for trimethylvinyltin, 6.5 min for trimethyltin chloride, 13.1 min for 4-tert-butylcyclohexen-l-yl trifluoromethanesulfonate, and 14.7 min for l-(4-tert-butylcyclohexen-l-y1)-2-propen-l-one. Because of the extreme Volatility of trimethylvinyltin, it may be necessary to add additional small amounts of this reagent in order to drive the reaction to completion. 

Pyrrolo[3,2-f]pyridine can be readily substituted with a variety of electrophiles at C-2 or C-3 after protection of the ring nitrogen atom. Derivatives can be synthesized with substituents such as iodo, methyl, trimethyltin, formyl, and allyl groups. The reactions proceed with excellent yields (47-95%) <200583581 >. 

Trimethyltin hydride adds mainly 1,2 to piperylene, but a variety of other organotin compounds are also formed. This suggests that the reaction may be a radical addition (IS). 

Metal-Nitrogen Compounds. Very little work has been done on addition reactions of metal-nitrogen compounds. The trimethyltin dimethylamide apparently does undergo reactions analogous to those of the trialkyltin alkoxides just discussed. For example, the following reactions were observed with carbon dioxide, carbon disulfide, and phenylisocyanate (57) ... 

Coupling of 69 with methyl 4-hydroxyphenoxyacetate 70 was carried out in the presence of imidazole and confirmed by gel-phase 13C NMR of PSDES resin 71. The hydrolysis of resin-bound ester was efficiently achieved using trimethyltin hydroxide (TMTOH) [110-114] to give the corresponding immobilized carboxylic acid 72. For the key Staudinger reaction, activation of the carboxylic acid 72 by Mukaiyama s reagent 74 was employed (Scheme 20) [115-117]. The m-p-lactam 16 was obtained in a 12-14% isolated yield. 

Although no coordination complexes of tetraalkyltins with nucleophiles (i.e. Lewis bases) have been reported, it is known that trialkyltin chlorides can form coordination complexes with various Lewis bases. Bolles and Drago38 have shown that trimethyltin chloride forms 1 1 complexes with bases such as acetone, acetonitrile, dimethylsulphoxide, and pyridine. All of these complexes are formed exothermally (in inert solvents such as CC14), with values of Af/299 ranging from —4.8 to —8.2 kcal.mole-1 for the reaction... 

A mixture of l-[(2 -cyanobiphenyl-4-yl)methyl]-2-ethoxybenzimidazole-7-carboxylate (0.7 g) and trimethyltin azide (0.7 g) in toluene (15 ml) was heated under reflux for 4 days. The reaction mixture was concentrated, and to the residue were added methanol (20 ml) and 1 N HCI (10 ml). The solution was stirred at room temperature for 30 minutes and adjusted to pH 3-4 with 1 N NaOH. After removal of the solvent, the residue was partitioned between chloroform and water. The organic layer was evaporated to dryness to dive a syrup. The syrup was purified by column chromatography on silica gel to give crystals. Recrystallization from ethyl acetate-benzene afforded colorless crystals ethyl 2-ethoxy-l-[[2 -(lH-tetrazol-5-yl)biphenyl-4-yl]-methyl]benzimidazole-7-carboxylate (0.35 g, 45%), M.P. 158-159°C. 

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