Cas 69380-65-0,1,2-O-isopropylidenehexane-1,2,6-triol 6-p-toluenesulphonate

DIASTEREOMERIC LINKING REAGENTS FOR NUCLEOTIDE PROBES

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, (2021/04/02)

A versatile reagent with a non-nucleotide monomeric unit comprising an enantiomeric center and having a ligand, and first and second coupling groups that are linked to the non-nucleotide monomeric unit. Such a reagent permits preparation of versatile nucleotide/non-nucleotide polymers, having any desired sequence of nucleotide and non-nucleotide monomeric units, each of the latter of which bear a desired ligand. These polymers can, for example, be used as probes which can exhibit enhanced sensitivity and/or which are capable of detecting a genus of nucleotides each species of which has a common target nucleotide sequence of interest bridged by different sequences not of interest.

Design of liquid crystalline block molecules with nonconventional mesophase morphologies: Calamitic bolaamphiphiles with lateral alkyl chains

Koelbel,Beyersdorff,Xiao Hong Cheng,Tschierske,Kain,Diele

, p. 6809 - 6818 (2007/10/03)

Novel bolaamphiphiles, consisting of a biphenyl rigid core, polar 2,3-dihydroxypropoxy groups at each terminal end, and an additional long alkyl chain in a lateral position have been synthesized. The structures of these ternary block molecules were systematically changed by variation of the length and position of the alkyl chain, by introduction of additional spacer units between one of the 2,3-dihydroxypropyl groups and the rigid core, and by replacement of one of the 2,3-dihydroxypropoxy groups by a single hydroxy group. The influence of these structural variations on the liquid crystalline properties of these new materials was investigated by polarized-light microscopy, differential scanning calorimetry, and X-ray diffraction. These investigation have shown that, by elongation of the lateral chain, a transition from a smectic monolayer structure (SmA1) via a strongly distorted layer structure (SmA+), a centered rectangular columnar phase (Colr/c2mm) and a noncentered rectangular columnar phase (Colr/p2gg) to a hexagonal columnar phase (Colh/p6mm) takes place. Elongation of the bolaamphiphilic core leads to the loss of the columnar phases, which are replaced by smectic phases, whereas reduction of its length favors the hexagonal columnar phase. This phase sequence is explained as a result of the microsegregation of the lateral alkyl chains from the rigid aromatic cores. The segregated alkyl chains are organized in columns that interrupt the smectic layers. The hydrogen bonding keep the bolaamphiphilic cores fixed end to end, so that they form networks of cylinders around the lipophilic columns. The space required by the alkyl chains with respect to the length of the bolaamphiphilic cores is restricted and largely determines the geometry of the cylinders, which leads to the observed phase sequence. The obtained mesophase morphologies, built up by three distinct sets of subspaces, are related to morphologies of some ternary block copolymers. Furthermore, the investigated compounds represent a novel class of materials, capable of forming supramolecular columnar mesophases.

Syntheses of homologous omega-aminated 1-methoxyalkyl beta-D-glucopyranosides as potential beta-D-glucosidase inhibitors.

Lehmann,Ziser

, p. 53 - 67 (2007/10/02)

(R)- and (S)-2-Azido-1-methoxyethyl beta-D-glucopyranosides (16) and (17), (R)- and (S)-3-azido-1-methoxypropyl beta-D-glucopyranosides (18) and (19), (R,S)-4-azido-1-methoxybutyl beta-D-glucopyranoside (20), and (R,S)-5-azido-1-methoxypentyl beta-D-glucopyranoside (22) were synthesized from omega-substituted dimethyl acetals of acetaldehyde, propanal, butanal, and pentanal by trimethylsilyl triflate-catalysed transacetalation using 1-O-trimethysilyl 2,3,4,6-tetra-O-acetyl-beta-D-glucose (1) as acceptor. Most of the acetylated (R,S)-epimers could be resolved into pure compounds by column chromatography. Preliminary tests showed that the deacetylated acetal glucosides carrying omega-bromo, azido, or acetamido substituents in the aglycon are good substrates for beta-D-glucosidase from sweet almonds. The corresponding omega-amino derivatives of compounds 16, 19, 20, and 22, (R)-2-amino-1-methoxyethyl beta-D-glucopyranoside (23), (S)-3-amino-1-methoxypropyl beta-D-glucopyranoside (24), (R,S)-4-amino-1-methoxybutyl beta-D-glucopyranoside (25), and (R,S)-5-amino-1-methoxypentyl beta-D-glucopyranoside (26) proved almost completely resistant to beta-D-glucosidase. The stability of the glucosides against enzyme hydrolysis is dependent on the distance between the amino group and the anomeric center.

Pyrroles as Terminators in Cationic Cyclizations. The Preparation of 5,6,7,8-Tetrahydroindolizidines and 6,7,8,9-Tetrahydro-5H-pyrroloazepines

Tanis, Steven P.,Raggon, Jeffrey W.

, p. 819 - 827 (2007/10/02)

N-(Epoxyalkyl)pyrroles 8-13 are readily prepared either by direct pyrrole N-alkylation with either ω-iodo epoxides or ω-iodo-1,2-alkanediol acetonides followed by conversion to the corresponding epoxides.The cyclizations of these N-(epoxyalkyl)pyrroles were examined with a range of Lewis acids providing cyclized products 14 and 16-21 in moderate to excellent yields.The cyclization products 14, 16, and 20 are formally the products of "anti-Markovnikov" attack on the less substituted epoxide terminus.