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Synlett 2007(3): 0505-0506  
DOI: 10.1055/s-2007-968003
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

Sodium Azide (NaN3): A Versatile Reagent in Organic Synthesis

Jian-Jiong Li*
The College of Chemistry & Material Science, Hebei Normal ­University, Shijiazhuang 050016, P. R. of China
e-Mail: organicsynchem@163.com;

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Publikationsdatum:
07. Februar 2007 (online)

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Biographical Sketches

Jian-Jiong Li was born in Handan, Hebei Province (P. R. of China). She received her BSc in Applied Chemistry from Hebei Normal University of Science and Technology, P. R. of China. Presently she is working as a postgraduate at Hebei Normal University, under the supervision of Professor Zhan-Hui Zhang. Her research interest ­focuses on the development of new synthetic methodologies using Lewis acids as catalysts.

Introduction

Sodium azide is a colorless, odorless, white crystalline solid, which is commercially available and widely used in industry, agriculture, medical practice, and organic ­transformations. It has been used for synthesis of β- and γ-azidoarylketones, [1] dialkylcarbamoyl azides, [2] diphen­ylphosphoryl azides, [3] acyl azides, [4] aryl azides, [5] allyl azides, [6] 1,5-fused tetrazoles, [7] 5-substituted 1H-tetrazoles, [8] 1,2,3-triazoles, [9] 1-aryl 1,2,3-triazoles, [10] 1,4-disubstituted 1,2,3-triazoles, [11] and 1-N-glycosylthio­methyl-1,2,3-triazoles. [12] In addition, sodium azide has been widely employed for preparation of α-azido­ketones, [13] 1-aryl-1H-benzotriazoles, [14] 3-cyanoindoles, [15] and Fmoc-protected amino alcohols, [16] as a suitable ­nucleophile for the Michael-induced ring closure of 2-bromoalkylidene­malonates to 3,3-dialkyl-2-azidocyclopropane-1,1-dicarboxylates. [17]

Abstracts

(A) Sreedhar et al. have developed an efficient method for the ­regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles from a variety of Baylis-Hillman acetates and terminal alkynes with ­sodium azide using CuI as a catalyst in PEG-400 at room tem­perature. [18a] This one-pot reaction has also been performed in ­ethanol using a catalytic amount of copper turnings and copper ­sulfate solution. [18b]

(B) A simple and efficient process for the direct conversion of ­carboxylic acids into carbamates has been demonstrated via ­Curtius rearrangement. The use of a mixture of di-tert-butyl di­carbonate and sodium azide allows the transformation of aliphatic carboxylic acids into alkyl azides, which rearrange to produce the corresponding isocyanates. Trapping of the isocyanates in the ­reaction mixture led to the desired carbamates in high yields. [19]

(C) Very recently, an efficient and convenient method has been ­developed for the synthesis of 1-substituted 1H-1,2,3,4-tetrazole compounds from amines, triethyl orthoformate and sodium azide catalyzed by Yb(OTf)3. [20]

(D) A regioselective ring opening of aziridines with sodium azide can be carried out at room temperature using montmorillonite KSF/SiO2 as promoter. Aryl aziridines underwent cleavage in a ­regioselective manner with preferential attack at the benzylic ­position to give products 2. Alkyl-substituted terminal aziridines gave the ring-opened products 3 resulting from terminal attack of NaN3. [21]

(E) The simple and most straightforward synthetic method for the preparation of 2-azidoalcohols involves the regioselective ring opening of oxiranes with sodium azide. This reaction can be carried out in the presence of Lewis acids [22] or in ionic liquids-H2O systems. [23]

(F) A facile and efficient method for the synthesis of amides from ­ketones and sodium azide via Schmidt reaction using P2O5/SiO2 ­under solvent-free microwave irradiation has been developed. [24]

(G) Sodium azide has been used as the direct azide source in an easy and convenient synthesis of β-azidocarbonyl compounds in water. [25]

(H) Sharpless and co-workers have reported a two-step protocol for the synthesis of a series of polyfunctional NH-1,2,3-triazoles. [26] Propargyl azides, prepared in situ from propargyl halides or ­sulfonates with sodium azide, underwent a thermal rearrangement sequence to triazafulvene intermediates, which were readily ­captured by diverse nucleophiles.

(I) Sodium azide has also been used as a reductant for reduction of 1,4-benzoquinones to hydroquinones under neutral conditions in the presence of water. [27]

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