“…After reduction with diisobutylaluminium hydride and catalytic bishydroxylation of 70 and 74 with osmium tetroxide, respectively, separation of the isomers is feasible via benzoylation to separate the L-glycero-L-gulo derivative 71 from the D-glycero-D-manno-heptoside 72, or via acetylation to isolate the crystalline L-glycero-D-manno-heptoside derivative 76 " Fig. (14)" [134,135]. Although the number of steps is high, the procedure is reliable to give multi-gram amounts of the 1 and 2.…”
Section: B) Synthesis Of Heptose Phosphatesmentioning
Heptoses are important higher-carbon sugars occurring in numerous structural variations in several domains of the bacterial cell wall, which are briefly summarized. Recent approaches towards the chemical and chemo-enzymatic synthesis of these microbial monosaccharides will be summarized as well as progress made in the elucidation of two major biochemical pathways involving the synthesis of heptose phosphates and nucleotide-activated heptoses.
“…After reduction with diisobutylaluminium hydride and catalytic bishydroxylation of 70 and 74 with osmium tetroxide, respectively, separation of the isomers is feasible via benzoylation to separate the L-glycero-L-gulo derivative 71 from the D-glycero-D-manno-heptoside 72, or via acetylation to isolate the crystalline L-glycero-D-manno-heptoside derivative 76 " Fig. (14)" [134,135]. Although the number of steps is high, the procedure is reliable to give multi-gram amounts of the 1 and 2.…”
Section: B) Synthesis Of Heptose Phosphatesmentioning
Heptoses are important higher-carbon sugars occurring in numerous structural variations in several domains of the bacterial cell wall, which are briefly summarized. Recent approaches towards the chemical and chemo-enzymatic synthesis of these microbial monosaccharides will be summarized as well as progress made in the elucidation of two major biochemical pathways involving the synthesis of heptose phosphates and nucleotide-activated heptoses.
“…As an additional example of utilization in a synthetic route, we applied our setup and methodology within the established synthetic approach towards d - glycero - d - manno heptose 9 (Scheme 4) [34, 35], which is the biological precursor of 3 . The key intermediate 5 (derived from d -mannose in multiple steps) underwent OsO 4 mediated dihydroxylation to deliver dd - manno -isomer 6 as a mixture with the minor ll - gulo isomer 7 [34, 35].…”
Section: Demonstration Of Successful Upscaling To Multigram Quantitiesmentioning
A continuous flow procedure for the synthesis of methyl glycosides (Fischer glycosylation) of various monosaccharides using a heterogenous catalyst has been developed. In-depth analysis of the isomeric composition was undertaken and high consistency with corresponding results observed under microwave heating was obtained. Even in cases where addition of water was needed to achieve homogeneity—a prerequisite for the flow experiments—no detrimental effect on the conversion was found. The scalability was demonstrated on a model case (mannose) and as part of the target-oriented synthesis of d-glycero-d-manno heptose, both performed on multigram scale.Graphical abstract
Electronic supplementary materialThe online version of this article (10.1007/s00706-018-2306-8) contains supplementary material, which is available to authorized users.
“…5) were prepared by hydrazinolysis of pure D-xylose and D-arabinose, respectively, following literature procedures. 13 Heptopyranosides were synthesized by addition of allyloxymethyl magnesium chloride to D-manno-aldehyde 6 (Scheme 1) followed by deprotection of the primary hydroxyl group by (PPh 3 ) 3 RhCl and Dabco to furnish a mixture of products.…”
Section: Synthesis Of Acyclic Diols and Triolsmentioning
confidence: 99%
“…So far structural determination studies on this class of compounds have been limited to NMR, optical rotation, and melting point measurements of derivatives requiring, in most cases, large amounts of material. 3 As part of our ongoing efforts to develop new methodologies for assigning absolute configurations of acyclic systems using the exciton chirality circular dichroic method, 4 we have undertaken studies on heptopyranosides and heptofuranosides in order to devise a microscale approach for their structural elucidation.…”
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