Reductive detelluration

Reductive detelluration of aryldichlorotellurolactones (general procedure) f To a solution of the dichloroteUurolactone (1 mmol) in deoxygenated toluene, (10 mL), under reflux and N2, is added dropwise BujSuH (4 mmol). The reaction is monitored by TLC. After 4 h the solvent is evaporated and the residue chromatographed on Si02 (eluted first with petroleum ether to remove Te and Sn by-products, and then with petroleum ether/EtOAc, 1 5), giving the tellurium-free lactone. 

Reductive detelluration of cyclic dichlorotelluroethers (general procedure) This procedure is identical to that described for dichlorotellurolactones (see Section 4.5.1.5). 

Reductive detelluration of cyclic telluroethers (typical procedure) To a solution of 2,3-diliydro-2-[(phenylteUuro)methyl]benzofuran (0.338 g, 1 mmol) in toluene (6 ml.) is injected TBTH (0.67 ml, 2.5 mmol) at room temperamre, and the resulting solution is stirred under reflux for 1 h. The solution is evaporated under vacuum and the residual yellowish oil subjected to Si02 column chromatography (eluting with benzene/hexane, 3 1) to give pure 2,3-dihydro-2-methylbenzofuran as a colourless oil (0.128 g (95%) b.p. 93-94°C/23 torr). 

Further examples of reductive detelluration of tellurium compounds have been shown in connection with tellurolactonization and telluroetherification reactions (see Section 4.5). 

The synthetic utility of the described reactions is clearly illustrated by the reductive detel-luration of telluroethers with BujSnH, the entire telluration/detelluration process providing a cyclization under mild conditions for unsaturated alcohols. 

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