Hydrogen azide epoxidation

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]. 

Trichlorobenzene. Trichloroethylene Hydrogen azide, see Alachlor. Aldicarb. Atrazine Hydrogen bromide, see Ethylene dibromide Hydrogen chloride, see Atrazine. Captan. Carbon tetrachloride. Chloroform. Chlorpropham. Chlorpyrifos. 1.2-Dichloroethane. Diuron. Endrin. Formaldehyde. Heptachlor. Heptachlor epoxide. Hexachlorocyclopentadiene. Linuron. Methyl chloride. Methylene chloride. Methyl formate. Monuron. Propanil. Tetrachloroethylene. Trichloroethylene. Vinyl chloride Hydrogen cyanide, see Acetontrile. Alachlor. Aldicarb. 

DL-Valiolamine (205) was synthesized from the exo-alkene (247) derived from 51 with silver fluoride in pyridine. Compound 247 was treated with a peroxy acid, to give a single spiro epoxide (248, 89%) which was cleaved by way of anchimeric reaction in the presence of acetate ion to give, after acetylation, the tetraacetate 249. The bromo group was directly displaced with azide ion, the product was hydrogenated, and the amine acety-lated, to give the penta-A, 0-acetyl derivative (250,50%). On the other hand. 

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. 

Cleavage of epoxides The epoxide 1 is cleaved by N3Si(CH3)3 and a catalytic amount of ZnCl2 to the hydroxy azide 2 in 90% yield. The corresponding benzoate (3) on hydrogenation undergoes O — N benzoyl transfer to provide 4 in 95% ee. 

The reaction of the epoxides of cyclopentene and cyclohexene with sodium azide give the trans-azido alcohols, the hydrogenation of which affords the trans isomers of 2-aminocyclopentanol and 2-aminocyclohaexanol (eq. 9.94) stereospecifically.246 By using these reactions, Swift and Swern prepared stereochemically pure cis- and trans-1,2-diaminocyclohexanes by the reaction sequences described in Scheme 9.23.247... 

The addition of iodine azide to primary allylic alcohols occurred with complete regio- and simple diastereoselectivity allowing the direct preparation of valuable 3-azido-1,2-epoxides, e.g., 12 and 13, by base-promoted elimination of hydrogen iodide from the intermediate 3-azido-2-iodo alcohols44. 

A mechanism that explains some of the more important observations in the acid-catalyzed hydrolysis of epoxides 49a-d is outlined in Scheme 15. The cis/trans diol product ratios from the acid-catalyzed hydrolysis of 49a-c, which have either hydrogen- or electron-donating groups in the para position of the phenyl ring, are 74 26, 83 17 and 65 35, respectively. An intermediate carbocation 52a is trapped by azide ion in the acid-catalyzed hydrolysis of 49a and the rate constant for reaction of 52a with water in 10 90 dioxane-water solvent is estimated, by the azide clock technique, to be 1.7 x 108 s 1. Azide ion also traps an intermediate 52b in the acid-catalyzed hydrolysis of 49b, but somewhat less efficiently. The rate constant ks for reaction of 52b with solvent is estimated to be 2 x 109 s-1. The somewhat greater reactivity of 52b compared to that of 52a is consistent with the observation that... 

The p-tolylsulfonyl epoxide 111, readily available (see Sect. V,l) from levoglucosan (6), reacts with a series of reagents, such as alcohols, ammonia, azides, halides, hydrogen, and thiols, to give the 4-substituted derivatives of l,6-anhydro-2-0-p-tolylsulfonyl-/3-D-gluco-pyranose (139), where X is H,742 734 OH,504 MeO,499 505 Me2CHO,496... 

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