Júlia Mičová

An efficient and versatile synthesis of apiose and some C-1-aldehyde- and/or 2,3-O-protected derivatives

Abstract The synthesis of 2,3- O -isopropylidene-β- d -apiofuranose (58% overall yield) from l -arabinose via 3- C -(hydroxymethyl)-2,3- O -isopropylidene- d - glycero -tetrose diethyl dithioacetal is reported. Starting from l -arabinose an alternative precursor of d -apiose, 3- C -(hydroxymethyl)-2,3- O -isopropylidene- d - glycero -tetrose dimethyl acetal, was prepared from 2,3- O -isopropylidene- l - threo -tetrodialdose dimethyl acetal and formaldehyde by the aldol-Cannizzaro reaction. Unprotected d -apiose is accessible from both precursors on acid hydrolysis.

6-O-Cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactopyranose

The analysis of the title compound, C14H21NO6, revealed a highly distorted conformation of the six-membered pyranose ring. The presence of two five-membered 1,3-dioxolane rings fused to the pyranose ring at the 1,2- and 3,4-positions is responsible for the severe deviation from the usual chair conformation of the pyranose ring. The three-dimensional packing is stabilized by weak hydrogen bonds of the C-H...O type.

Some amino sugars structurally related to 6-deoxymannojirimycin precursors prepared from methyl 6-deoxy-2,3-O-isopropylidene-α-d-lyxo-hexofuranosid-5-ulose and methyl 2,3-O-isopropylidene-α-d-lyxo-pentodialdo-1,4-furanoside

Methyl (5S)-5-C-amino-5-cyano-5-deoxy-2,3-O-isopropylidene-alpha-D-lyxofuranoside has been synthesised from methyl 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside, applying the Strecker synthesis. Analogously, methyl (5S) and (5R)-5-C-amino-5-cyano-5,6-dideoxy-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosides were prepared from methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosid-5-ulose. The 5-S configuration was unambiguously determined by single-crystal X-ray diffraction analysis of corresponding N-acetyl derivatives. Conformations of five-membered rings are discussed. The conversion of N-acetylated amino nitriles to N-acetylamino acid ethyl ester and amide, respectively, is also described.

2-(1H-Benzimidazol-2-ylsulfanyl)butanoic acid

The title compound, C11H12N2O2S, forms ionic crystals consisting of protonated benzimidazole cations and carboxylic acid anions, C11H13N2O2+·C11H11N2O2-. In both ions, the bicyclic 1H-benzimidazole core is essentially planar. The plane of the 2-alkylsulfanyl substituent is almost coplanar with the benzimidazole plane. The three-dimensional packing is stabilized by strong intermolecular N-H...O and O-H...N interactions and weak C-H...O intermolecular hydrogen bonds.

3‐O‐Benzo­yl‐1,2‐O‐isopropyl­idene‐β‐d‐fructopyran­ose

In the structure of the title compound, C 16 H 20 O 7 , the five-membered 1,3-dioxolane ring is disordered with two different positions, A and B (1/1); it adopts the O T 4 conformation slightly distorted towards E 4 for molecule A, and the 1 E conformation distorted towards 1 T O for molecule B. The pyranose ring adopts an almost ideal 1 C 4 conformation. The three-dimensional packing is stabilized by strong intermolecular O-H...O interactions and weak C-H...O hydrogen bonds.