Synthesis of enantiopure C-glycosides and pseudo C-glycosides: Lewis-acid mediated heterolysis of methyl acetals

Gaertzen, Oliver; Misske, Andrea M.; Wolbers, Peter; Hoffmann, H. M. R.

doi:10.1016/s0040-4039(99)01224-1

Cited by 25 publications

(11 citation statements)

References 18 publications

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“…Lewis acid-promoted reactions of acetals of type 16 with allyltrimethylsilane are well-established for the generation of C-glycosides possessing the required α-stereochemistry. 10 Construction of the sp 2 -sp 3 bond of 16 at C-6 was considered possible by reaction of a functionalised organometallic of type 18 with a suitable electrophile 19 (Scheme 2). Although Grignard or organolithium reagents incorporating esters are generally considered to be synthetically non-viable, recent work by Knochel 11 and Oshima 12 and their co-workers indicates that reagents 18 should be accessible.…”

Section: (I) Formal Total Synthesis Of (؉)-Apicularen Amentioning

confidence: 99%

“…After 4 h, the solvent was evaporated and the residue purified by flash chromatography (petroleum ether : EtOAc, 30 : 1) to give the title compound 30 (485 mg, 83%) as a colourless oil; R f 0.84 (petroleum ether : EtOAc, 1 : 1); ν max /cm Ϫ1 (thin film) 2979, 2940, 1731, 1584, 1567, 1461, 1430, 1264, 1104; δ H (270 MHz, CDCl 3 ): 7.37 (dd, 1 H, J = 8.0, 0.5 Hz), 7.03 (t, 1 H, J = 8.0 Hz), 6.87 (d, 1 H, J = 8.0 Hz), 4.41 (q, 2 H, J = 7.0 Hz), 3.79 (s, 3 H), 1.40 (t, 3 H, J = 7.0 Hz); δ C (67.9 MHz, CDCl 3 ): 167. (13), 203 (10), 151 (5).…”

Section: Methyl 3-o-[tert-butyl(diphenyl)silyl]-24-dideoxy-d-threohex...mentioning

confidence: 99%

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A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products

et al. 2002

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A synthesis of apicularen precursor (-)-6 in 18 steps from D-glucal is reported. As (+)-6 has been converted into the potent, naturally occurring salicylate anti-cancer agent, (-)-apicularen A in 8 steps, this study constitutes a formal total synthesis of (+)-apicularen A. Key steps in the synthetic route include: (i) useful D-glucal elaboration processes, (ii) organometallic displacements at carbohydrate C-6 triflates using Knochel-type and related functionalised, aromatic Grignard reagents, (iii) stereoselective allyltrimethylsilane-acetal reactions generating C-allyl systems, (iv) stereocontrolled aldehyde allylation processes from both substrate and reagent, and (v) a novel Keck-type macrolactonisation. In addition, preliminary studies are reported in which a procedure has been devised to convert apicularen-derived intermediates into salicylihalamide-like products.

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Section: (I) Formal Total Synthesis Of (؉)-Apicularen Amentioning

confidence: 99%

Section: Methyl 3-o-[tert-butyl(diphenyl)silyl]-24-dideoxy-d-threohex...mentioning

confidence: 99%

A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products

et al. 2002

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“…Although O ‐ and C ‐glycosylation reactions using anomeric 6,1‐lactones, in particular glucopyranurono‐6,1‐lactone, have been reported,20–22 their use as glycosyl donors for nucleoside synthesis is, to the best of our knowledge, unprecedented.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Purine Nucleosides from D‐Glucuronic Acid Derivatives and Evaluation of Their Cholinesterase‐Inhibitory Activities

et al. 2014

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Glucuronolactones were used as precursors for N9 and N7 purine nucleosides containing glucuronic acid derivatives in their structures. Acetylated N‐benzylglucofuran‐ and glucopyranuronamides were synthesized in a few steps from glucofuranurono‐6,3‐lactone. They were converted into the corresponding furanosyl and pyranosyl uronamide‐based nucleosides by N‐glycosylation with silylated 2‐acetamido‐6‐chloropurine in the presence of trimethylsilyl triflate. The triacetylated bicyclic lactone was coupled itself with the nucleobase to give bicyclic N9,N7 nucleosides. Tri‐O‐acetylglucopyranurono‐6,1‐lactone was used for the first time as a glycosyl donor for N‐glycosylation, and led to β‐configured N9‐ and N7‐linked purinylglucuronides under reaction conditions similar to those used with the 1‐O‐acetyl‐substituted glycosyl donors. The cholinesterase inhibitory profiles of the synthetic nucleosides bearing glucuronic acid derivatives as glycons were evaluated, and they showed moderate selective acetylcholinesterase inhibitory activities (Ki = 14.78–50.53 μM). The best inhibition was shown by the furanosyl N9‐linked uronamide‐based purine nucleoside.

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“…Various transitions within the general D ‐ L , D ‐ D and L ‐ L frame have been effected experimentally. An activated leaving group is not necessarily required for glycosylation: Even tetrahydropyran acetals with methoxide ion as supposedly poor leaving group serve as glycosyl donors42 in acetonitrile. It is of biogenetic and general interest that naturally occurring C‐linked glycosides belonging to the l‐l category, but outside the conventional carbohydrate area, are also rare.…”

Section: Perspectives—conclusion—modus Operandimentioning

confidence: 99%

Photoresponsive Supramolecular Systems: Self‐Assembly of Azodibenzoic Acid Linear Tapes and Cyclic Tetramers

Rakotondradany

Whitehead

Lebuis

et al. 2003

Chemistry A European J

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A new strategy to effect photoinduced control over molecular self-assembly is reported. This strategy uses the reversible trans-cis photoisomerization of a novel azobenzene system, where the trans- and cis-forms self-assemble into dramatically different higher-order structures. The trans-azobenzene form of this molecule associates into infinite hydrogen-bonded linear tapes, while the cis-azobenzene form undergoes hydrogen-bonded self-assembly into cyclic tetramers. This results in a second level of association, where the cis-hydrogen-bonded supramolecular cycles ultimately form long, rod-like aggregates through stacking interactions.

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Synthesis of enantiopure C-glycosides and pseudo C-glycosides: Lewis-acid mediated heterolysis of methyl acetals

Cited by 25 publications

References 18 publications

A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products

A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products

Synthesis of Purine Nucleosides from D‐Glucuronic Acid Derivatives and Evaluation of Their Cholinesterase‐Inhibitory Activities

Photoresponsive Supramolecular Systems: Self‐Assembly of Azodibenzoic Acid Linear Tapes and Cyclic Tetramers

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