Electrotelluration: a new approach to tri- and tetrasubstituted alkenes

A novel electrotelluration process is 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 tetrasubstituted alkenes. Methodologically significant examples of this chemistry were studied in which aryl and alkyl tellurolate anions were added to omega-keto alkynyl esters in a Michael reaction, and the incipient vinyl anions were trapped intramolecularly by the internal aldehydes. The reactive centers were tethered by different lengths of alkyl chains to form highly functionalized five-, six-, seven-, and eight-membered rings in modest to good yields.