Butyltin moieties

Table II. Relative Atomic Absorbance and Luminescence Intensities (at 457 nm) of Various Butyltin Moieties Accumulated on Cells...

Exchange reactions of this type but involving tributyltin and butyltin moieties have also been studied (251) and are summarized in Eqs. (135) and (136). 

The nucleophilic displacement of the iodine moiety in 2-iodoben-zoates mediated by triphenyltin hydride and di-n-butyltin dichloride in aqueous solution has been demonstrated (Eq. 6.16).33 For example, 2-iodobenzoic acid reacts with a toluene solution of Ph3SnH/l,3-(N02)2 C6H4/aq. NaHC03 to give 89% yield of salicylic acid. 

Long exposure of workers to DBT moieties caused bile-duct damage and exposure to TPhT compounds caused liver damage34. This is probably due to high biliary excretion rate of butyltin compounds. 

Allenes have also been used as substrates in free radical cyclizations. Dener and Hart demonstrated that such entries are valuable in constructing pyrrolizidine and indolizidine ring systems [71]. In a total synthesis of pyrrolizidine base (+)-heliotri-dine (340), compound 338 possessing an allene functionality was used as a key intermediate (Scheme 19.62). Tri-n-butyltin radical-mediated carbon-selenium bond homolysis of 338 followed by the addition of the free radical to the allene moiety... 

Chlorodi- -butyltin hydride (Bu2SnClH) promotes regio- and stereo-selective hydrostannation of propargylic ethers without any additives or catalysts to give /3-(Z) adduct as single isomer (Equation (34)). Effective coordination of ether oxygen to tin moiety determines the selectivity.100,101... 

In a similar manner, N-Cbz leucinal reacted with the ylid of the phosphonate ester shown to give a 15 1 mixture of 6.133 6.134. Stirring this mixture in acetonitrile gave a 98 2 mixture of 6.135 6.136. Reduction of the iodo moiety with tri-n-butyltin hydride, followed by basic hydrolysis, gave statine methyl ester in 45%... 

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