Alcohols 2-azido

Nucleophilic ring opening of epoxides by ammonia (Section 16 12) The strained ring of an epoxide is opened on nucleo philic attack by ammonia and amines to give 3 ammo alcohols Azide ion also re acts with epoxides the products are p azido alcohols... 

Synthesis of azindines Irom epoxides via amino alcohols or azido alcohols and reaction with phosphines or phosphites... 

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. 

The azido alcohol is dissolved in a minimal amount of dry pyridine and cooled in an ice bath. Methanesulfonyl chloride (1 ml/g of azido alcohol) is added to the cold solution. The reaction mixture is allowed to stand at 0° for 24 to 72 hr. The reaction mixture is processed by pouring into ice water and either filtering the product, if possible, or by extraction with an organic solvent. Methanol or methanol-ether have been used to recrystallize the crude azido mesylates. 

S,3S)-(+)-Aziridine-2,3-dicarboxylic acid (234 Scheme 3.86), an example of a naturally occurring aziridinecarboxylic acid, is a metabolite of Streptomyces MD398-A1. This aziridine was prepared by treatment of diethyl (2i ,3K)-(-)-oxir-ane-2,3-dicarboxylate (231) with trimethylsilyl azide in EtOH/DMF to produced azido alcohol 232 [137], and treatment of this alcohol with triphenylphosphine afforded the aziridine dicarboxylate 233 in 71 % yield. Hydrolysis of 233 afforded the natural product 234 in 69% yield. 

The DKR of functionalized alcohols such as diols, hydroxy esters, hydroxy aldehydes, azido alcohols and hydroxy nitriles was also taken up as the synthetic uhlity of the products is very high besides such a study will bring out the effect of multifunctional substrates under these reaction conditions to broaden the scope of DKR. Initially, the DKR of diols was achieved with diruthenium catalyst 1... 

The DKRs of (J-azido alcohols and p-hydroxy nitriles were also accomplished hy employing 1 and CALB with PCPA as the acyl donor. The DKRs of p-azido alcohols were performed at 60°C while those of (3-hydroxy nitriles required higher temperature (100°C) primarily to enhance the racemization rate. The optical purities of products were satisfactory in all cases. In the case of p-hydroxy nitriles, dehydrogenation lowered the yield. 

Similarly, diethylaluminum azide gives (3-azido alcohols. The epoxide of 1-methylcyclohexene gives the tertiary azide, indicating that the regiochemistry is controlled by bond cleavage, but with diaxial stereoselectivity. 

By combining several click reactions, click chemistry allows for the rapid synthesis of useful new compounds of high complexity and combinatorial libraries. The 2-type reaction of the azide ion with a variety of epoxides to give azido alcohols has been exploited extensively in click chemistry. First of all, azido alcohols can be converted into amino alcohols upon reduction.70 On the other hand, aliphatic azides are quite stable toward a number of other standard organic synthesis conditions (orthogonality), but readily undergo 1,3-dipolar cycloaddition with alkynes. An example of the sequential reactions of... 

Ring opening of oxiranes using azide is followed by Staudinger reduction of the intermediate azido alcohol to give aziridines. 

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

With azidotrimethylsilane in the presence of a stoichiometric amount of a chiral complex prepared from dichlorodiisopropoxy titanium(IV) and di-rm-butyl L-tartrate, (15,2.S )-1,2-azido alcohols are obtained only in moderate yield with moderate enantiomeric excess1040. 

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. 

Alkyl azides can be prepared by treatment of the appropriate halide with azide ion.939 Phase transfer catalysis940 and ultrasound941 have been used. Other leaving groups have also been used,942 for example, OH,943 OMs, OTs,944 and OAc.945 Epoxides react with NaN3, with HN3 in DMF,94 or with HN3-Et3Al947 to give 3-azido alcohols these are easily converted to aziridines,948 e.g.,... 

Cyclization of haloamines 0-46 Cyclization of amino alcohols 0-61 Cyclization of p-azido alcohols 5-31 From 3-iodo azides... 

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). 

Based on this sequence, Blum et a/.158 have reported a general synthesis of unsubstituted K-region arene imines from the corresponding arene oxides. K-Imines of benz[a] anthracene, 7-methylbenz[a]anthracene, dibenz [a,/i] anthracene, and benzo[a] pyrene have been prepared. Azido alcohol formation from these oxides is generally nonregiospecific and both possible regioisomers of the azido alcohols are formed in different proportions. 

Both samarium iodide and ytterbium triisopropoxide catalyse the ring opening45 of epoxides by TMS-azide in the latter case, due to an acidic work-up, the products are isolated as vicinal azido alcohols. 

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