Studies on Tetrahydrofuran basedhighly O-Functionalized Alkynes:Applications to Synthesis of

Abstract

Enantiomerically pure tetrahydrofuran bearing alkynes (17–20) have been synthesized by using various methods. By utilizing these alkynes, an efficient CuI catalysed sp-sp carbon homo-coupling protocol in dry DMF without using other additives like, amine or base, phosphine and palladium catalyst has been developed. The method has been applied towards the synthesis of symmetrical butadiynyl (32–37), octatetraynyl (47) and dodecahexaynyl (49) polyynes. The unsymmetrically substituted diynes (39, 40 and 41) and triynes (43 and 44) have also been synthesized by coupling reaction between the newly synthesized bromoalkyne/diynes (38/42) and commercial trialkylsilylacetylenes. Synthesis of 1,2,3-triazolyl C-nucleoside analogue (51), ethynyl- and butadiynyl-bridged 1,2,3-triazolyl C-nucleoside analogues (52 and 53) by 1,3-dipolar cycloadditions of their respective precursor mono- (17), di- (46) and tri- (48) alkynes with THF azide (50) involving “click” chemistry has also been exemplified