| Autor: |
Pradhan P; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India., Moktan S; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India., Biswas A; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India., Das A; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India., Lenka R; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India., Kancharla PK; Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India. |
| Abstrakt: |
The triple role of 1,8-bis(dimethylamino)naphthalene (proton sponge) as a reductant, ligand precursor, and organic base in the palladium-catalyzed Heck-type coupling reaction of glycals with aryl iodides affords the rapid and stereoselective synthesis of 2',3'-unsaturated α- C -aryl glycosides in excellent yields. The role of the proton sponge in reducing palladium(II) to (0) has been studied using cyclic voltammetry, UV-vis, HRMS, and other spectroscopic techniques. This is the first example of a palladium proton sponge complex utilized in coupling reactions. The method is observed to be tolerant of various functional groups, as demonstrated by the huge substrate scope. Moreover, the 2',3'-unsaturated α- C -aryl glycosides were also converted to 3-keto-β- C -glycosides under sterically hindered pyridinium salt catalysis via a ring-opening and -closing mechanism. |
