Thiocarbonates as Blocking Groups for the Synthesis of Partial Esters of Carbohydrates

Abstract

I t has been found that the thiocarbonate, or (alky1thio)carbonyl derivative, serves as a versatile blocking group for the synthesis of partial ester derivatives of carbohydrates. T h e (allc~~lthio)carbo~i~~l group is readily substit~ited in pyridine solution, is stable to ~iiild acid conditions, but is deconlposed by mild oxidation. Crystalline methyl 4,6-di-0-benzoyl-a-Dglucopyranoside has been synthcsized and its structure proved by an independent synthesis of its 2,3-di-0-phenylcarbamate derivative. Methyl 4,6-di-0-benzoyl-p-D-glucopyrai~oside was also synthesized and its structure proved by acetylation to the linown 2,s-di-0-acetyl derivative.

The SYNTHESIS OF 3-O-[(Benzylthio)carbonyl]-Β-D-Glucopyranose AND METHYL 2,4,6-Tri-O-Benzoyl-Α AND Β-D-Glucopyranosides

“…A recent paper (3) described the synthesis of methyl 2-O-[(benzylthio)carbonyl]-a-~-glucopyra~~oside, which served as a precursor to methyl 3,4,6-tri-0-benzoyl-a-D-glucoppranoside, by a specific substitution of the (benzy1thio)carbonyl group a t C-2 in methyl 4,B-0-benzylidenea-D-glucopyranoside. The thiocarbonate ester, C&--CH2-S-CO-0-, serves as a useful blocking group for the synthesis of partial esters of carbohydrates due to the ease with which it can be removed without cleavage of other ester groupings (4).…”

Design of Photostable, Activatable Near‐Infrared Photoacoustic Probes Using Tautomeric Benziphthalocyanine as a Platform

“…We also prepared the activatable PA imaging probe 8 for H 2 O 2 , a reactive oxygen species that plays a role in various diseases (Scheme ) . The S ‐benzyl thiocarbonate moiety was reported to be removed by reaction with H 2 O 2 , so we attached this protecting group to the hydroxyl group of 6 . Compounds 7 and 8 did not exhibit NIR absorption beyond 700 nm because they are fixed in the phenol form (Figure S3‐1).…”

Design of Photostable, Activatable Near‐Infrared Photoacoustic Probes Using Tautomeric Benziphthalocyanine as a Platform

“…Communications prepared the activatable PA imaging probe 8 for H 2 O 2 , areactive oxygen species that plays arole in various diseases (Scheme 2). [11] The S-benzyl thiocarbonate moiety was reported to be removed by reaction with H 2 O 2 , [12] so we attached this protecting group to the hydroxyl group of 6. Compounds 7 and 8 did not exhibit NIR absorption beyond 700 nm because they are fixed in the phenol form ( Figure S3-1).…”