Homo‐ and Cross Coupling of C‐2 Propargyl Substituted Triterpenoic Acids: Synthesis of Novel Symmetrical and Unsymmetrical Triterpene 1,3‐Diynes

Abstract

A synthesis of the first representatives of symmetrical and unsymmetrical triterpene 1,3‐diynes in which one or two triterpene cores are linked by a diyne spacer at the C‐2 position of ring A is described. The new triterpenoids are prepared by Cu‐ and Pd‐catalyzed acetylenic homo‐ and cross coupling of accessible C‐2 propynyl derivatives of betulinic, ursolic, and oleanolic acids.