Tellurolactonization

Tellurolactonization of 4-pentenoic acid (typical procedure) f To a solution of diphenyl ditelluride (0.102 g, 0.5 mmol) in freshly distilled MeCN (20 mL) is added solid NBSP (0.170 g, 0.5 mmol), in small portions at 0°C, and the solution is stirred for 10 min. 4-Pentenoic acid (0.130 g, 1.1 mmol) is added, the solution is stirred for 2 h at 0°C, then... 

Tellurolactonization of Ct-allenic acids with phenyltellurenyl chloride... 

If the dichlorotellurolactones are reduced previously to the parent tellurolactones by treatment with NaBH4, the successive detelluration saves 2 equiv of TBTH, and the... 

The title reagent, employed for tellurolactonizations (see Section 4.5.1.2), is also effective for the tellurocyclization of unsaturated alcohols. ... 

Cyclotelluroetherification (typical procedure). The procedure, starting from (PhTe)2 (0.5 mmol), NBSP (0.5 mmol), 4-penten-l-ol or hexen-l-ol (1.1 mmol), is similar to that described for tellurolactonization (see Section 4.5.1.2). 

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

A tellurolactone of estrone series was synthesized starting from the estratien-17-one in accordance with the following scheme ... 

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