Alkynyl tin compound

Terminal acetylenes RC=CH, however, yield trialkyl(alkynyl)tin compounds on reaction with trialkyltin amides456 or alkoxides457 or with trialkyltin hydroxides458 or bis(trialkyltin) oxides 459... 

The hypervalent tin compound 350 reacts with the strong base lithium diethylamide leading to the elimination of chloride and subsequent coordination between B-N-Sn to form azoniastannaboratole derivative 351 (Equation 18) <2003JOM188>. The starting materials (m-borylstannanes 350) can be obtained by the organoboration of alkynyl-stannanes stereoselectively. 

Indium trichloride catalytically promotes the alkynylation of aldehydes in which InCl3 plays two roles transme-tallation with tin compounds and activation of aldehydes as a Lewis acid (Equation (65)).219... 

HA Is usually a volatile amine which can readily be removed to drive an equilibrium reaction to completion. Reactions of this type are useful for preparing cyclopentadienyl-, alkynyl-, trihalogenomethyl-, and diazoalkyl-tin compounds. 

Jesi and /csn couphngs have been used by Wrackmeyer et a/. in order to follow the reaction between 1-boraadamantane and di(l-alkynyl)silicon and -tin compounds of the type (Me2M(C = C)R)2, M = Si or Sn, and to characterise some novel 7-metalla-2,5-diboranorbornane derivatives obtained as products. 

Vinyllead and alkynyllead tricarboxylates can only be prepared by metal-metal exchange, such as mercury-lead,ll6 ll7 tin-lead,ll6,ll7 boron-lead i or zinc-lead.l In the case of tin-lead exchange, cleavage of the methyl-tin bond is much slower than cleavage of the vinyl-tin or alkynyl-tin bond. Therefore (trimethyl)vinyltin derivatives are preferred to the corresponding (tributyl)vinyltin analogues for the synthesis of the unstable vinyllead and alkynyllead compounds. 

Analogous reactions afford other compounds of the type R3SnR, such as alkyl(tri(cycloalkyl)]tin,408 alkyl(triphenyl)tin,409 alkenyl-(trialkyl)tin and -(tri-aryl)tin,398,410 and alkynyl(triaryl)tin compounds 411 also compounds of the general formula R2SnR 2, such as dialkyl- and diaryl-bis(perfluorovinyl)-tin412 and dialkynyl(diaryl)tin compounds.413... 

The alkyne insertion reaction is terminated by anion capture. As examples of the termination by the anion capture, the alkenylpalladium intermediate 189, formed by the intramolecular insertion of 188, is terminated by hydrogenolysis with formic acid to give the terminal alkene 192. Palladium formate 190 is formed, and decarboxylated to give the hydridopalladium 191, reductive elimination of which gives the alkene 192 [81]. Similarly the intramolecular insertion of 193 is terminated by transmetallation of 194 with the tin acetylide 195 (or alkynyl anion capture) to give the dienyne 196 [82], Various heterocyclic compounds are prepared by heteroannulation using aryl iodides 68 and 69, and internal alkynes. Although the mechanism is not clear, alkenylpalladiums, formed by insertion of alkynes, are trapped by nucleophiles... 

When we want to transfer a group from tin we do not want to waste three of them. The rule is that tin transfers the best anion to palladium (strengthening our view that the organotin compound is the nucleophile). Alkynyl groups are transferred best and the order for other groups is roughly as below. 

The reaction of a tin tetrahalide with a Grignard reagent or an organolithium compound has been used also for synthesis of the following compounds SnR4 R = cycloalkyl, alkenyl, or alkynyl, e.g., cyclopropyl,396 vinyl,397,398 trifluorovinyl,399 cis- and ms-propenyl,400 (cyclohexylethynyl) 281 substituted and unsubstituted (phenylethynyl) 282,401 ring-substituted aryl of very various types, e.g., w-(trifluoromethyl)phenyl, p-fluorophenyl,402 and pentafluor ophenyl.2 7 8... 

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