Synthesis of Heptamannoside, Lactam Glycoconjugates and Spirocyclic Glycooxazolines

Abstract

Glycoconjugates are ubiquitous in nature, decoding their significant influence on a variety of biological processes including virus replication, immunological response, cell-cell communication, fertilization, and cell proliferation requires pure glycoconjugates. Naturally occurring glycans and glycoconjugates are particularly difficult to isolate due to their availability of micro heterogeneous nature. And hence the chemical synthesis of such organic compounds resolves the challenges associated with such synthesis and is required to attain purity and in abundance. In my thesis, the synthesis of vaccine candidate Heptamannoside for M. tuberculosis along with serendipitous results that we got while performing the glycosylation or glycosyl donor preparation. The Heptamannoside was synthesized using the silver assisted gold-catalyzed glycosidation for all glycosidations. In addition to that a methodology for synthesising lactam conjugates also was developed from results while preparing the glycosyl donor required wherein DBU was reacted with glycosyl carbonate. We noticed formation of interesting DBU opening that was optimized so that one can afford interesting lactam. In yet another effort, a Ritter-like reaction was carried out for the formation of spirooxazole. These efforts are demonstrated with a number of substrates.