Electrotelluration: A New Approach to Tri- and Tetrasubstituted Alkenes
作者:Joseph P. Marino、Hanh Nho Nguyen
DOI:10.1021/jo0110146
日期:2002.9.1
described in which a Michael addition of an alkyl or aryl tellurolate anion occurs onto an activated alkyne with subsequent trapping of a vinyl anion with electrophiles (aldehydes and ketones) other than a proton. This process provides an efficient regio- and stereospecific route to tri- and tetrasubstitutedalkenes. Methodologically significant examples of this chemistry were studied in which aryl and alkyl
o-Cyanobenzyllithium (3) was efficiently generated by lithium-tellurium exchange of the corresponding benzylic telluride 2 prepared in situ from lithium butanetellurolate and α-bromo-o-tolunitrile (1). Reaction of ketones or aldehydes with 3 afford substituted 2-hydroxyethylbenzonitriles 4 in high yields. The subsequent acid-catalyzed lactonization gave 3-substituted 3,4-dihydroisocoumarins 5 in good yields. All these successive reactions could be performed in the same reaction flask without isolation of intermediates.
Methyl Ester Function: An Intramolecular Electrophilic Trap for the Isolation of Aryltellurenyl Hydroxide and Diorganotellurium Dihydroxide
作者:K. Selvakumar、Harkesh B. Singh、Nidhi Goel、Udai P. Singh
DOI:10.1021/om2001553
日期:2011.7.25
ellurinyl)isophthalate (7) and methyl 5-tert-butyl-3-oxo-3H-benzo[c][1,2]oxa tellurole-7-carboxylate (9). The telluroxide intermediate 7 readily undergoes a facile elimination reaction to give the elusive aryltellurenyl hydroxide, which is immediately trapped by the adjacent methylester functionality to give the cyclic tellurenate ester 9. Similarly, the hydrolysis of 7 with H2O affords the corresponding
Tellurium in organic synthesis: an approach to the synthesis of (Z,E)-dienic precursors of insect pheromones
作者:Dennis G. Diego、Rodrigo L.O.R. Cunha、João V. Comasseto
DOI:10.1016/j.tetlet.2006.08.005
日期:2006.10
A simple and straightforward route to (Z,E)-dienic precursors of insect pheromones was developed. The route features a cross-coupling of a (Z,E)-dienic telluride with an alkyl Lipshutz cuprate.
Carbon–carbon bond formation by means of organotellurium compounds
作者:R Barrientos-Astigarraga
DOI:10.1016/s0022-328x(00)00828-7
日期:2001.3.30
vinylic halides, phosphates, sulphonates and acetates leading to the Z vinylic telluride exclusively. Tellurides are transmetallated with easily available organometallic reagents to give valuable synthetic building blocks (e.g. organolithiums and organocuprates). Reaction of vinylic tellurides with alkynes under Pd catalysis or with organocuprates gives the coupling products with retention of the double bond