Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the Mycobacterium tuberculosis cellular envelope by glycosyl carbonate donorsElectronic supplementary information (ESI) available: Experimental procedures, compound characterization data and spectral charts. See DOI: 10.1039/c6sc04866h

• Main Authors: Islam, Maidul, Shinde, Ganesh P, Hotha, Srinivas
• Format: Journal Article
• Language: English
• Published: 28-02-2017
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c6sc04866h

The global incidence of tuberculosis is increasing at an alarming rate, and
Mycobacterium tuberculosis
(Mtb) is the causative agent for tuberculosis, a disease with high mortality. Lipoarabinomannan (LAM) is one of the major components of the Mtb cellular envelope and is an attractive scaffold for developing anti-tubercular drugs, vaccines and diagnostics. Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time. The arabinomannan synthesized in this endeavour has several 1,2-
trans
or α-Ara
f
linkages and three 1,2-
cis
or β-Ara
f
linkages end capped with 1,2-
trans
or α-Man
p
linkages. All the key glycosidations were performed with alkynyl carbonate glycosyl donors under [Au]/[Ag] catalysis conditions, which gave excellent yields and stereoselectivity even for the reactions between complex and branched oligosaccharides. The resultant allyl oligosaccharide was globally deprotected to obtain the heneicosasaccharyl arabinomannan as a propyl glycoside. In summary, heneicosasaccharyl mannose capped arabinomannan synthesis was achieved in 56 steps with 0.016% overall yield.
Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time.