Substitution de sulfites cycliques osidiques par l'ion azoture

Synthesis of Optically Pure 3,4-Disubstituted l-Glutamates from a Novel 2,3-Aziridino-γ-lactone 4-Carboxylate Derivative

“…Nucleophilic attack of azide anion exclusively at the C-3 position of 11 was evident from the 1 H NMR spectrum of the product 12 in which the anomeric proton was observed as a singlet, indicative of a trans arrangement with H-2. Such complete regioselectivity of attack of carbohydrate cyclic sulfinyl groups by azide anion has previously been observed 3 …”

“…However, these authors were not able to displace either of the tosyl groups by azide anion, presumably due to steric hindrance produced by the trityl group. Since the cyclic sulfinyl moiety is generally a better leaving group than tosyl, we chose to prepare the former derivative of 10 by the usual treatment with thionyl chloride and triethylamine. The resulting compound 11 , which is stable and easily purified by chromatography, then reacted smoothly with sodium azide in HMPA at 100 °C to give 12 .…”

Access to Antigens Related to Anthrose Using Pivotal Cyclic Sulfite/Sulfate Intermediates

“…Cyclic sulfites and sulfates have long been known as versatile electrophiles, and particularly as epoxide surrogates, in both noncarbohydrate and carbohydrate chemistry. , However, the substitution of cyclic sulfites (or sulfates) other than those involving the anomeric center or a primary hydroxyl group of a sugar has scarcely been studied despite its broad synthetic potential: To our knowledge, no attempt of substitution on a pyranoside 3,4-cyclic sulfate has been reported so far. On the other hand, Guiller et al reported the preparation of some methyl 4-azido-α- d -arabinopyranosides from their corresponding 3,4-cyclic sulfites in high yields and complete regioselectivity . However, when the same authors iterated the reaction on a (α- l -arabinopyranosyl)uracil derivative, the 3′-azido compound was the sole isolated product, in 50% yield, from a complex mixture in which they tentatively identified the presence of the 4′-azido regioisomer .…”

2,3-Aziridino-2,3-dideoxy-d-ribono-γ-lactone 5-Phosphonate: Stereocontrolled Synthesis from d-Lyxose and Unusual Aziridine Ring Opening

“…We have previously found 2,3-cyclic sulfite derivatives of ribofuranosides to be excellent substrates for the selective introduction of an azide function at C-3 of ribofuranosides, a necessary prelude to formation of the 2,3-aziridine ring. , The cyclic sulfite 14 of the lyxofuranoside 2,3-diol 10 was thus prepared by reaction of the latter with thionyl chloride and triethylamine in THF at −25 °C for 30 min (Scheme ) . However, treatment of 14 with sodium azide in DMF or HMPA led to decomposition of starting material at temperatures greater than 100 °C and no reaction below 100 °C.…”

“…16,25 The cyclic sulfite 14 of the lyxofuranoside 2,3-diol 10 was thus prepared by reaction of the latter with thionyl chloride and triethylamine in THF at -25 °C for 30 min (Scheme 3). 26 However, treatment of 14 with sodium azide in DMF or HMPA led to decomposition of starting material at temperatures greater than 100 °C and no reaction below 100 °C. The chemical instability of 14 is most probably the result of the acidity of the C-5 protons, due to the adjacent phosphonate group.…”