Epoxides sodium azide

The synthesis of p-hydroxy triazoles by the three-component reaction of a variety of epoxides, sodium azide, and diverse terminal alkyne reactions performed... 

A mixture of the epoxide ca. 5 mmol), sodium azide (6 g, activated by the method of Smith) and 0.25 ml of concentrated sulfuric acid in 70 ml of dimethyl sulfoxide is heated in a flask fitted with a reflux condenser and a drierite tube on a steam bath for 30-40 hr. (Caution carry out reaction in a hood.) The dark reaction mixture is poured into 500 ml of ice water and the product may be filtered, if solid, and washed well with water or extracted with ether and washed with sodium bicarbonate and the water. The crude azido alcohols are usually recrystallized from methanol. 

Treatment of 51 with an excess of sodium benzoate in DMF resulted in substitution and elimination, to yield the cyclohexene derivative (228, 36%). The yield was low, but 228 was later shown to be a useful compound for synthesis of carba-oligosaccharides. <9-Deacylation of228 and successive benzylidenation and acetylation gave the alkene 229, which was oxidized with a peroxy acid to give a single epoxide (230) in 60% yield. Treatment of 230 with sodium azide and ammonium chloride in aqueous 2-methoxyeth-anol gave the azide (231,55%) as the major product this was converted into a hydroxyvalidamine derivative in the usual manner. On the other hand, an elimination reaction of the methanesulfonate of 231 with DBU in toluene gave the protected precursor (232, 87%) of 203. 

An explosion was experienced dining work up of an epoxide opening reaction involving acidified sodium azide in a dichloromethane/dimethyl sulfoxide solvent. The author ascribes this to diazidomethane formation from dichloromethane [1]. A second report of an analoguous accident, also attributed to diazidomethane, almost certainly involved hydrogen azide for the cold traps of a vacuum pump on a rotary evaporator were involved this implies an explosive more volatile than dichloromethane. It is recommended that halogenated solvents be not used for azide reactions [2]. 

A rather complex microwave-assisted ring-opening of chiral difluorinated epoxy-cyclooctenones has been studied by Percy and coworkers (Scheme 6.131) [265]. The epoxide resisted conventional hydrolysis, but reacted smoothly in basic aqueous media (ammonia or N-methylimidazole) under microwave irradiation at 100 °C for 10 min to afford unique hemiacetals and hemiaminals in good yields. Other nitrogen nucleophiles, such as sodium azide or imidazole, failed to trigger the reaction. The reaction with sodium hydroxide led to much poorer conversion of the starting material. 

Highly regioselective opening of epoxides and aziridines with sodium azide and Oxone in aqueous acetonitrile in very high yield was reported (equation 52). ... 

Treatment of the epoxide 32 with sodium azide and ammonium chloride in dimethylformamide gave the azido alcohol 33 which, via the mesylate 34, could... 

Although we have not yet attempted the alkylation of the amine 81 with the epoxide 125, preliminary experiments with cyclohexylamine and with sodium azide have allowed the synthesis of the model compounds 126 and... 

Azidoalcohols (79, 81) can be accessed directly through the cerium-catalyzed addition of sodium azide onto mono-substituted epoxides. When the substituent is a simple alkyl or aryl group, nucleophilic attack at the more substituted epoxide carbon was observed i.e., 78 -> 79). However, when a phenoxy group was incorporated into the side chain (e.g., 80), a crossover to attack on the unsubstituted methylene carbon was encountered <99SC561>. 

The a-D-lyxo epoxide [232, R = (3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-glucofuranose-3-yl), R1 = CH2OH] was converted into a 3,4-unsat-urated D-threo-2,6-diol (268), which was dimesylated and the diester treated with sodium azide. Two diazides (673a and 673b) were obtained and separated the latter was hydrogenated in the presence of platinum catalyst and the product acetylated, to furnish 673c. 

Sodium azide reacts with various epoxides at 25°-30°C at pH 6-7 to give azido alcohols [57-59]. The use of harsh conditions as earlier employed by Van der Werf et al. [59] (16-40 hr reflux in dioxane) led to the production of 1,3-diazidopropanol instead of l-azido-3-chloro-2-propanol when starting with epichlorohydrin. Several representative examples of the conditions and products of the reaction of azides with epoxides are shown in Table V. 

Preparation of Organic Azide Compounds by the Reaction of Sodium Azide with Epoxides in Aqueous Solution [60]... 

Additionally, 1,2-dihydroxyethylene dipeptide analogues without the C-terminal carboxylic acid have been used to obtain aspartyl proteases inhibitors.[641 These efforts include stereoselective alkylation of imines, one-pot reductive amination of epoxy ketones, ring opening of epoxides with sodium azide, diastereoselective dihydroxylation of allylic amines, and enzymatic resolution and stereocontrolled intramolecular amidation. 

G. Miscettaneous Nwdeopkilic Additions (1) Azide ion. The ready cleavage of ethylene oxide rings by N. ion is in acoordanoe with its recognized nucleophilic character. Alllums-Ii so far limited to three,6 8-127 -1778 publications devoted to this reaction have explored the behavior of a wide assortment of epoxides. Jt. is customary to characterize 0-azido alcohol obtained on treatmml of epoxides with aqueous sodium azide by reduction to /1-atnirm aa-o-hok.iwo. ins aa shown in Eq. (896). 

Clycidol (Eq. 898) has been treated with aqueous sodium azide or aqueous hydraaoic acid.333 Approach of the reagent occurs toward the least-substituted epoxide carbon atom in both eases. The reaction of... 

Chiral a-hydroxy RSMAs are obtained from a-chiral silyl epoxides by classical trans addition of sodium azide followed by reduction of the intermediate a-hydroxy azide (see Section III.A.7).311... 

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