Few steps and a very good yield are characteristics of the block synthesis of a heptasaccharide that is the smallest strongly elicitor-active unit binding to a receptor in the host-parasite system, soybean/Phytophthora megasperma. The intermediates central to the block synthesis are the thiotrisaccharide donor 1 and the glycosyl acceptor 2 (Ac = CH3CO, Bz = C6H5CO, Bzl = C6H5CH2).

Comparable syntheses of beta-D-GlcpNAc-(1 --> 2)-[beta-D-GlcpNac--(1 --> 6)]-alpha-D-Manp-(1 --> 6)-beta-D-ManpO(CH2)8CO2Me and beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> 3)-beta-D-ManpO(CH2)8CO2Me with the glycosyl halide and imidate methods were investigated. 3,4,6-Tri-O-acetyl-2-deoxy-(2,2,2-trichloroethoxycarbonylamino)-alpha-D-glucopyranosyl bromide or trichloroacetimidate are suitable glycosyl donors for beta-D-glycoside coupling with secondary hydroxyl groups.

In the synthesis of 8-methoxycarbonyloctyl O-(α-d-galactopyranosyl)-(1→3)-O-(2-acetamido-2-deoxy-β-d-mannopyranosyl)- (1→4)-O-(β-d-glucopyranosyl)-(1→4)-α-d-glucopyranoside, which represents a component of the capsular polysaccharide of Streptococcus pneumoniae type 9V, the key step was the coupling of α-d-Galp-(1→3)-β-d-ManpNAc-(1→4)-d-Glc as glycosyl donor with 8-ethoxy-carbonyloctyl 6-O-acetyl-2,3-di-O-benzyl-α-d-glucopyranoside as glycosyl acceptor by use of the imidate method. Only the β-imidate of the trisaccharide could be employed in this glycosidation reaction to give stereoselectively the tetrasaccharide in high yield. The α-imidate of the trisaccharide led to hydrolysis of the imidate group.

AbstractRacemic carazolol (Ia) is converted into its N‐protected derivative (Ib) by treatment with di‐tert‐butyl carbonate (II).

In the presence of silver silicate as promoter, the reaction of glycosyl bromides of 2-azido-2-deoxy-d-mannose with 1,6-anhydro-2,3-di-O-benzyl-β-d-glucopyranose led to derivatives of the disaccharide β-d-ManpNAc-(1→4)-d-Glcp. The derivatives were activated into disaccharide halides and employed as glycosyl donors in block synthesis. By chain extension with l-rhamnose and d-glucose, four trisaccharides were synthesized. They represent components of capsular polysaccharide“repeating units” of various Streptococcus pneumoniae types, β-d-ManpNAc-(1→4)-α-d-Glcp-(1→2)-l-Rhap (type 19 F), β-d-ManpNAc-(1→4)-α-d-Glcp-(1→3)-l-Rhap (type 19 A), β-d-ManpNAc-(1→4)-α-d-Glcp-(1→4)-d-Glcp (type 9 A), and β-d-ManpNAc-(1→4)-β-d-Glcp-(1→4)-d-Glcp (type 9 V).

In the presence of silver silicate as promoter, the reaction of glycosyl bromide of 2-azido-2-deoxy-D-mannose with 1,6-anhydro-2,3-di-O-benzyl-beta-D- glucopyranose led to derivatives of the disaccharide beta-D-ManpNac-(1----4)-D- Glcp. The derivatives were activated into disaccharide halides and employed as glycosyl donors in block synthesis. By chain extension with L-rhamnose and D-glucose, four trisaccharides were synthesized. They represent components of capsular polysaccharide "repeating units" of various Streptococcus pneumoniae types, beta-D-Man-pNAc-(1----4)-alpha-D-Glcp-(1----2)-L-Rhap (type 19 F), beta-D-ManpNAc-(1----4)-alpha-D-Glcp-(1----3)-L-Rhap (type 19 A), beta-D-ManpNAc-(1----4)-alpha-D-Glcp-(1----4)-D-Glcp (type 9 A), and beta-D-ManpNAc-(1----4)-beta-D-Glcp-(1----4)-D-Glcp (type 9 V).

ChemInformVolume 18, Issue 35 Natural Products ChemInform Abstract: Building Units of Oligosaccharides. Part 83. Synthesis of the Repeating Unit of the Teichuronic Acid of Micrococcus luteus. H. PAULSEN, H. PAULSEN Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this authorB. HELPAP, B. HELPAP Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this authorJ. P. LORENTZEN, J. P. LORENTZEN Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this author H. PAULSEN, H. PAULSEN Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this authorB. HELPAP, B. HELPAP Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this authorJ. P. LORENTZEN, J. P. LORENTZEN Inst. Org. Chem., Univ. Hamburg, D-2000 Hamburg 13Search for more papers by this author First published: September 1, 1987 https://doi.org/10.1002/chin.198735333Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue35September 1, 1987 RelatedInformation

AbstractEs werden die zwei Disaccharide β‐D‐ManNAcA‐(1 → 6)‐D‐Glc (27) und α‐D‐Glc‐(1 → 4)‐D‐ManNacA (28) synthetisiert, die die Repeating unit der Teichuronsäure von Micrococcus luteus darstellen. Die Schlüsselschritte der Synthese des ersten Disaccharides sind die Herstellung der β‐glycosidischen Verknüpfung des Derivates der 2‐Azido‐2‐desoxy‐D‐mannose 8 zum Disaccharid 18 und die Einführung des Uronsäureteiles in das Disaccharid durch katalytische Oxidation mit Sauerstoff am Platinkontakt zu 23. Die Herstellung der α‐glycosidischen Verknüpfung im zweiten Disaccharid gelingt durch Umsetzung von 11 mit 16 bei Gegenwart von Quecksilbersalzen zu 26.