Synthesis of a 3-Thiomannoside

Abstract

An efficient and straightforward synthesis of a novel 3-thiomannoside derivative (1,2,4,6-tetra-O-acetyl-3-S-acetyl-3-thio-β-d-mannopyranoside) was developed starting from levoglucosenone. A xanthate-thiocarbonate exchange under acidic conditions was the key step for the new C-S bond. The product was obtained enantiospecifically in very good overall yield.

SnCl4-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

“…It is known that Sc(OTf) 3 [29,32] and trimethylsilyl trifluoromethanesulfonate [33] in the presence of acetic anhydride act as acetolysis agents to cleave the 1,6-anhydro ring. In these reactions, Ac 2 O is used as both reactant and solvent, which can be easily removed in vacuo.…”

“…Differently, ring-opening reactions of 6 with BF 3 ⋅OEt 2 , TMSOTf, and Sc(OTf) 3 in Ac 2 O afforded glycal 13 (Table 1, entries 1-4). None of these conditions were successful for the acetolysis of these 2,7-anhydro derivatives, although they worked for the 1,6-anhydro sugars [29,32,33]. Adding 10 equiv of acetic acid to suppress the 2,3elimination reaction failed to give the desired compound 12.…”

“…Moreover, it is the main precursor in the synthesis of inhibitors for N-acetylneuraminidases from different sources [42]. The ring opening of 5 was not trivial since the substrate had a sterically hindered quaternary anomeric center, unlike the tertiary anomeric center C-1 of 1,6-anhydro sugars [29][30][31][32][33]43]. Furthermore, SnCl 4 and Sn(OTf) 2 might have formed a coordination bond with the carbonyl oxygen atom of the C-5 NHAc group and the O-6 position of the glucose glucopyranosyl ring.…”

Levoglucosenone and Its New Applications: Valorization of Cellulose Residues

“…In this case, we also used the allylic xanthate 85 as precursor for an efficient and straightforward synthesis of a novel 3‐thiomannoside derivative (1,2,4,6‐tetra‐ O ‐acetyl‐3‐ S ‐acetyl‐3‐thio‐β‐ d ‐mannopyranoside) (Scheme ) . A cis ‐dihydroxylation of 85 under catalytic conditions afforded the diol 89 , further xanthate–thiocarbonate interconversion under acid mediated reaction was the key step for the new C–S bond formation in intermediate 90 .…”

A Domino Epoxide Ring‐Opening Xanthate Migration Reaction: An Alternative Entry to Thiosugars

“…Among the different strategies to incorporate a sulfur functionality into a carbohydrate skeleton, anhydro sugar derivatives have demonstrated to be very useful building blocks to achieve this goal. We have recently reported the stereospecific synthesis of a 3‐thiomannopyranoside starting from levoglucosenone (1,6‐anhydro‐3,4‐dideoxy‐β‐ d ‐ glycero ‐hex‐3‐enopyranos‐2‐ulose) ( 1 ), A xanthate‐thiocarbonate exchange under acidic conditions was the key step to build the C–S bond …”