Aziridines, sugar, preparation

The conversion of azidoformates to fused-ring aziridines via the thermal generation of a nitrene has previously been reported. More recently, the photolytic conversion of a sugar-derived azidoformate has been used to prepare fused-ring aziridines <06JOC8059>. Photolysis of azidoformate 66 at 254 nm provides aziridine 67 in excellent yield. The resulting bicyclic aziridine was reduced to provide oxazolidinone 68 in 95% yield. Oxazolidinone 68 was subsequently converted to L-daunosamine. 

The endo-spiro-OZT could be prepared through a reaction sequence similar to that applied for the exo-epimer, with spiro-aziridine intermediates replacing the key spiro-epoxides (Scheme 18). Cyanohydrin formation from ketones was tried under kinetic or thermodynamic conditions, and only reaction with the d-gluco derived keto sugar offered efficient stereoselectivity, while no selectivity was observed for reaction with the keto sugar obtained from protected D-fructose. The (R) -cyanohydrin was prepared in excellent yield under kinetic conditions (KCN, NaHC03, 0 °C, 10 min) a modified thermodynamic procedure was applied to produce the (S)-epimer in 85% yield (Scheme 18). 

The preparation of aziridines and substituted aziridines from a number of sugars that contain substituted amino groups has been described. With such compounds as the sulfonamide (241) and the cyanamide (231), where the functional groups are fmns-diaxial, aziridine formation is the expected course of the reaction under alkaline conditions. Baker and Hullar described the conversion of (241) into the substituted aziridine (188, R = Ts) with methanolic sodium methoxide at room temperature similar transformation of (231) into (242) was accomplished with alcoholic... 

The aziridinium-fused furanoside 221 was prepared from D-ribose derivative 220, and thence elaborated to acyclic aziridine 222 and compound 223, which are both 3,4-disubstituted L-glutamates (Scheme 16). [2+2] Cycloadditions of sugar vinyl ethers 224 and 225 to tosylcyanide followed by reduction with RedAl afforded the P-lactams 226 and 227. These were elaborated to the tricyclic systems 228 and 229. ... 

Enantiomerically pure ( )-conduramine C has been prepared (in ten steps and 23.3 % overall yield) via Sn2 bromination of 7-oxanorbomane derivative (—)-185 derived from the naked sugar (+)-170 (Scheme 29). Aziridination of alkene (+)-170 gives 179. Subsequent acidic treatment generates a dialkyloxybenzyl cation intermediate 180 that can be quenched with water to give the tra i-5,6-disubstituted... 

---