Novel silylated diols and polyols were prepared using a recently developed synthesis route with bifunctionalized silyl triflates. These silyl derivatives include two triflate functions, which allow a selective protection of two hydroxy groups. Moreover, the conformation of the silyl chain in the silane backbone led to exceptional UV properties.

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Twisting the silicon backbone conformation in oxygen containing oligosilanes towards dihedral angles of 120-130 degrees either by intramolecular hydrogen bonding or incorporation into a covalently bonded ring system effectively extends the delocalization of electrons in these sigma-n mixed conjugated systems.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The halogenated 1H-1,2,4-triazole glycosides 6–10 were synthesized by BF3-activated glycosylation of 3(5)-chloro-1,2,4-triazole (2), 3,5-dichloro-1,2,4-triazole (3), 3,5-dibromo-1,2,4-triazole (4), and 3(5)-bromo-5(3)-chloro-1,2,4-triazole (5) with 1,2,3,4-tetra-O-pivaloyl-β-d-xylopyranose (1). The β-anomeric major products 3-chloro-1-(2,3,4-tri-O-pivaloyl-β-d-xylopyranosyl)-1,2,4-triazole (6β), 3,5-dichloro-1-(2,3,4-tri-O-pivaloyl-β-d-xylopyranosyl)-1,2,4-triazole (7β), and 3,5-dibromo-1-(2,3,4-tri-O-pivaloyl-β-d-xylopyranosyl)-1,2,4-triazole (8β) were used as starting materials for transition metal catalyzed C–C-coupling reactions. Arylations of the triazole ring of 7β, and 8β were successful in 5-position with phenylboronic acid, 4-vinylphenylboronic acid, and 4-methoxyphenylboronic acid, respectively, under Suzuki cross-coupling conditions (products 11–17). Moreover, a Cu-catalyzed perfluoroalkylation of 8β is reported with 1-iodo-perfluorohexane yielding 3-perfluorohexyl-1-(2,3,4-tri-O-pivaloyl-β-d-xylopyranosyl)-1,2,4-triazole (18). Compound 18 was depivaloylated to the trihydroxy derivative 19. The copper-mediated reaction of 8β with Rupert's reagent gave the bis(3-bromo-1-(2,3,4-tri-O-pivaloyl-β-d-xylopyranosyl)-1,2,4-triazol-5-yl) (20).

The dithionite-mediated addition of BrCF2Cl to 3,4-di-O-pivaloyl-d-xylal (1) generated preferably 1-CF2Cl-substituted products, that is, (2-bromo-2-deoxy-3,4-di-O-pivaloyl-β-d-xylopyranosyl)-chlorodifluoromethane and (2-deoxy-3,4-di-O-pivaloyl-β-d-threo-pentopyranosyl)-chlorodifluoromethane. Selected chlorodifluoromethyl-substituted monosaccharide derivatives were hydrodechlorinated or alkylated at the CF2Cl-group using tin reagents under radical reaction conditions. Thus, hydrodechlorinations of (2,3,4-tri-O-acetyl-6-deoxy-α-l-galactopyranosyl)-chlorodifluoromethane and of methyl 3,4-di-O-acetyl-2-C-chlorodifluoromethyl-2,6-dideoxy-α/β-l-glucopyranoside are reported using tri-n-butyltin hydride initiated by AIBN. UV-initiated allylations are reported for reactions of (2-deoxy-3,4-di-O-pivaloyl-β-d-threo-pentopyranosyl)-chlorodifluoromethane, (2,3,4-tri-O-acetyl-6-deoxy-α-l-galactopyranosyl)-chlorodifluoromethane, 1,3,4,6-tetra-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-α-d-glucopyranose, 1,3,4,6-tetra-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-α-d-mannopyranose and methyl 3,4-di-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-α/β-d-rabinopyranoside with allyltri-n-butyltin.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

1,2,4-Triazole nucleoside analogues bonded at N-1 of the base were synthesized by addition of N-halo-3,5-dibromo- 1,2,4-triazoles to 1,2-unsaturated carbohydrate derivatives (glycals). Examples are given for 1,5-anhydro-3,4,6-tri-O-acetyl-2-deoxy-D-arabino-hex-1-enitol (tri-O-acetyl-D-glucal), and 1,5-anhydro-3,4,6-tri-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (tri-O-benzyl-D-glucal), respectively. The graduated reactivity of the three halogens [C-5 (triazole) > C-2 (sugar) > C-3 (triazole)] in the addition products allows subsequent regioselective replacement and deprotection reactions like hydrodehalogenations, Ducleophilic substitutions (by methoxide, hydrazine, benzylamine, thiophenolate), deacetylations, and debenzylations, respectively. Thus, the paper opens a new synthetic approach to triazole nucleoside analogues of 2-deoxy-sugars. X-ray analyses support the structures of nine products.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Regioselective one-pot O-silylation reactions of 1,2-O-isopropylidene-alpha-D-glucoftiranose and 1,2-O-isopropylidene-beta-Dfructopyranose using bulky oligosilyl groups are described. Some new silylating reagents (oligosilyl bistriflates), which were generated in situ from readily available phenylsilanes, resulted in 5,6-O-(glucofuranose) and 4,5-0-bridged (fructopyranose) carbohydrates with favoured seven- and eight-membered rings. In these cyclic oligosilyl diethers, three and four ring atoms, respectively, are Si atoms. It is noteworthy, that the seven-membered ring of 5,6-O-[2,4bis(trimethylsilyt)-1,1,1,3,3,5,5,5-octamethylpentasilan-2,4-diyl]- 1,2-O-isopropylidene-Ot-D-glucofuranose was expanded to an eight-membered ring by regioselective insertion of aerial oxygen into one of the Si-Si bonds. X-ray analyses of some derivatives are presented.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A convenient two-step strategy is reported for the synthesis of fluorinated optically pure acyclo-C-nucleoside analogues starting from simple glycals. In the first step, benzyl- or p-methoxybenzyl-protected glycals are treated with trifluoroacetic anhydride, bromodifluoroacetyl chloride, trichloroacetyl chloride, and perfluorooctanoyl chloride, respectively, in the presence of Et3N. This one-pot procedure yields 1,2-unsaturated sugars (1,5-anhydro-3,4,6-tri-O-benzyl (or p-methoxybenzyl) 2-deoxy-2-perhalogenoacyl-d-arabino / lyxo-hex-1-enitols 4–9) acylated at C-2. In the second step, a selective ring transformation is induced by treatment of the C-acylated glycals with bis-nucleophiles (hydrazine, phenylhydrazine, o-phenylenediamine, hydroxylamine). In particular, 1,5-anhydro-3,4,6-tri-O-benzyl-2-deoxy-2-trifluoroacetyl-d-arabino-hex-1-enitol (4) and 1,5-anhydro-2-deoxy-2-trifluoroacetyl-3,4,6-tri-O-(p-methoxybenzyl)-d-arabino-hex-1-enitol (8) were reacted with these nucleophiles generating the final C-nucleoside analogues of pyrazole (10, 11, and 12), diazepine (13), and isoxazole (15), respectively, containing a carbohydrate side chain linked to the heterocyclic ring.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An efficient procedure was established to synthesize a thymidine analogue bearing an acylsilane function at the 5'-position, starting from thymidine in four steps and 58% overall yield. This compound proved to be a valuable intermediate for the synthesis of various nucleoside analogues with a one-carbon chain elongation at the 5'-position and a useful compound towards the construction of modified oligonucleotides.

The dithionite-mediated chlorodifluoromethylations of 3,-di-O-acetyl-1,5-anhydro-2,6-dideoxy-L-arabino-hex-1-enitol (1), 1,5-anhydro-2,3,4-tri-O-pivaloyl-D-erythro-pent-1-enitol (13) 2,3,4-tri-O-acetyl-1,5-anhydro-6-deoxy-L-lyxo-hex-1-enitol (15), and 2,3,4,6-tetra-O-acetyl-1,5-anhydro-D-arabino-hex-1-enitol (18) with CBrClF2 in acetonitrile-water and methanol, respectively, are described. Sodium dithionite serves as radical initiator and reducing reagent. Whereas, starting with 1, the chlorodifluoromethyl group was predominantly introduced into position 2, the 1-chlorodifluoromethyl substituted C-glycosides 1,5-anhydro-1-(S)-chlorodifluoromethyl-2,3,4-tri-O-pivaloyl-D-ribitol (14), 2,3,4-tri-O-acetyl-1,5-anhydro-1-(R)-chlorodifluoromethyl-6-deoxy-L-galacti-tol (16), and 2,3,4,6-tetra-O-acetyl-1,5-anhydro-1-(S)-chlorodifluoromethyl-D-glucitol (19) could be synthesized in moderate to good yields from 13, 15, and 18, respectively. X-ray analyses are given for the products 3,4-di-O-acetyl-1,5-anhydro-2-chlorodifluoromethyl-2,6-dideoxy-L-glucitol, 1,3,4-tri-O-acetyl-2-chlorodifluoromethyl-2,6-dideoxy-alpha-L-mannopyranose, 1,5-anhydro-1-(S)chlorodifluoromethyl-2,3,4-tri-O-pivaloyl-D-ribitol, and 2,3,4,6-tetra-O-acetyl-1,5-anhydro-1-(S)-chlorodifluoromethyl-D-glucitol.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

l-1-Deoxy-1-fluoro-6-O-methyl-myo-inositol was epimerized by chloral/DCC in boiling 1,2-dichloroethane yielding D-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol. The latter and l-4-O-benzyl-3-O-cyclohexylcarbamoyl-5-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-muco-inositol, l-4-O-benzyl-3-O-cyclohexylcarbamoyl-1,2-O-ethylidene-5-O-methyl-muco-inositol, d-1-O-cyclohexylcarbamoyl-2-deoxy-5,6-O-ethylidene-2-fluoro-3-O-methyl-chiro-inositol, as well as D-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N'-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol were deprotected with boiling 57% aq hydrogen iodide. Ether, urethane and ethylidene acetal functions were simultaneously cleaved by the reagent, whereas the trichloroethylidene groups were still intact or were only removed in small quantities. Especially, the urea function of D-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N'-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol was decomposed to a cyclohexylamino group. The hydrodechlorination of D-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol using Raney-Nickel yielded a mixture of the corresponding 5,6-O-ethylidene- and 5,6-O-chloroethylidene derivatives. The three synthetic steps-hydrodehalogenation, HI-deprotection and peracylation- were combined without purification of the intermediates.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

C6H11FO5, monoclinic, P12(1)1 (no. 4), a = 6.8060(2) angstrom b = 16.7719(6) angstrom, c = 6.8130(2) angstrom, beta = 106.621(1)degrees, V = 745.2 angstrom(3), Z = 4, R-gt(F) = 0.030, wR(ref)(F-2) = 0.065, T = 173 K.