Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

Abstract

SummaryThe TMSOTf-mediated synthesis of β-configured spirocyclic 2-substituted-2-oxazoline ribosides was achieved using a “Ritter-like” reaction in toluene through nucleophilic addition of electron-rich nitriles to the oxacarbenium ion intermediate of 1,2;3,4-di-O-isopropylidene-β-D-psicofuranose derivatives with concomitant intramolecular trapping of the C2 hydroxymethyl group on the electrophilic nitrilium carbon. These carbohydrate-derived spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group.

Solid‐Phase Synthesis of Clickable Psicofuranose Glycocarbamates and Application of Their Self‐Assembled Nanovesicles for Curcumin Encapsulation

“…Our efforts in this direction started from our previously reported synthesis of 6-deoxy-6-((9H-fluoren-9-yl)methylcarbamate)-1,2;3,4-di-O-isopropylidene-β-D-psicofuranose 1 from D-(-)-fructose. [11] Compound 1 was treated with azidotrimethylsilane and trimethylsilyltriflate at 0°C for 45 min to afford 2-azido trimethylsilyl ether 2a and an inseparable mixture containing 2-azido alcohol 2b and bicyclic product 2c (Scheme 1). [12] Compounds 2b and 2c have almost the same polarity and could not be separated by column chromatography.…”

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

“…The 3,4-dimethylphenyl p -nitrophenyl carbonate ( 9a ) and geranyl carbonate 10a gave the corresponding γ-lactams 9b and 10b in 62% and 46% yields, respectively. Similarly, the p -nitrophenyl carbonate of D-psicofuranose [28], n -pentenyl 2,3,4-tri- O -benzyl-α-D-mannopyranoside [32–34] and 2,3-di- O -benzyl-α-methyl-D-arabinofuranoside [35] (Table 2, 11a–13a) gave the γ-lactam-derived carbamates 11b–13b in 53%, 63% and 67% yield, respectively.…”

“…Although p -nitrophenyl carbonates were extensively utilized in these reactions, the nucleophilicity of amidine bases towards these carbonates was not encountered so far. In continuation of our interest in carbohydrates [28–29] and the synthesis of carbamate-linked compounds using p -nitrophenyl carbonates, we herein report our results from nucleophilic ring opening reactions of DBU and DBN using p -nitrophenyl carbonates.…”

Synthesis of Spironucleosides: Past and Future Perspectives

“…Also related to spironucleosides are the recently described spiro-oxazoline furanosides 186 [ 92 ] Their synthesis was achieved using a TMSOTf-promoted nucleophilic addition of electron-rich nitriles to the oxacarbenium ion intermediate of reaction of protected psicofuranose derivative 215 ( Scheme 40 ). In addition to their pharmacological interest, spiro-fused carbohydrate oxazoline derivatives have potential applications in asymmetric catalysis [ 93 ].…”