Study on the new synthetic reactions using vinylic tellurides

Abstract

Electrophile-induced rearrangement of borate chemistry are used as the strategy for stereoselective synthesis of 1-substituted ($_1E$, $_3E$)-1,3-butadienyl phenyl tellurides and internal vinylic tellurides which could be applicable as main part-structure of many natural products and insect pheromones. In this case, only preferential migration of the alkenyl or alkyl group from boron to the adjacent alkynyl sp-carbon takes place. Pheromone of the Leafroller moth Phtheochroa cranaodes Meyrick (Lepidoptera: Tortricidae) was synthesized via a concise and versatile strategy that utilized electrophile-induced rearrangement of suitably prepared lithium 1-octynylborate with $Me_3SnCl$. Hydrozirconation of acetylenic tellurides were found to proceed stereoselectively in cis fashion with high regioselectivity affording 1,1-bimetalloalkenes of tellurium and zirconium. The intermediates were converted to ketene organyltelluroacetals after treatment with organyltellurenyl iodides. The intermediates were cleaved with essentially complete retention of configuration by organyltellurenyl iodides to give ketene organyltelluroacetals, which were difficult to prepare by other means. 1,1-Bimetalloalkenes(tin and selenium, tin and tellurium) were stereoselectively prepared by hydrozirconation of acetylenic stannanes and then transmetallation via tellurenyl iodide and selenenyl bromide. One equivalent of n-BuLi displaced a trialkylstannyl group selectively to generate lithiated vinyl selenides which were reacted with electrophiles to afford (E)-internal selenides. The rac-chokol G are synthesized via the 1,4-addition reaction of suitably prepared functionalized cuprate reagent to commercially available 2-methyl-2-cyclopenten-1-one. The reaction of zirconacyclopentadiene with 1 equivalent of phenyltellurenyl iodide produced tellurophene and PhTePh. With 2 equivalent of phenyltellurenyl iodide, the reaction also produced tellurophene in improved isolated yield.