Heck reaction of 2-methyl-5-vinyl-2H-tetrazole with iodoarenes

Abstract

SHORT COMMUNICATIONSVinyltetrazoles and their derivatives are promising substrates in the synthesis of various tetrazolecontaining polymers with valuable properties utilized in medicine and engineering [1]. Synthesis of some derivatives of vinyltetrazoles, in particular, of styryltetrazoles, is poorly understood.In a series of publications [2, 3] the synthesis of styryltetrazoles, containing substituents with strong electron-acceptor properties (F, NO 2 , CN, CO 2 H) in the aryl fragment based on cross-coupling of С-, Nvinyltetrazole with halobenzenes by Heck reaction is described. However no information exists on the synthesis of similar compounds containing electrondonor substituents. The electronic effect of the substituent in the aromatic fragment may significantly affect the efficiency of this reaction. The nature of the halogen present in the haloarene and the composition of the catalytic system are also of fundamental importance [4][5][6][7].In this study we synthesized styryltetrazoles 3a-3d, containing in the para-position of the aromatic fragment donor (Me, t-Bu, MeO) and weakly acceptor (Cl) substituents. In the reaction with 2-methyl-5-vinyl-2Н-tetrazole iodoarenes 2a-2d were used applying as a catalyst Pd(OAc) 2 . The reaction was carried out in the presence of K 2 CO 3 in DMF at heating.In all cases the reaction proceeded with high yields (73-80%). The cross-coupling occurs stereoselectively affording exclusively Е-2-methyl-5-styryltetrazoles 3a-3d, as show the large values of the spin-spin coupling constants ( 3 J 16.5 Hz).Hence, 2-methyl-5-vinyl-2H-tetrazole enters in Heck reaction with iodoarenes containing not only electron-acceptor (as has been shown in [2,3]), but also electron-donor substituents at the use as a catalytic system Pd(OAc) 2 in the presence of K 2 CO 3 in DMF. (3a-3d). General procedure. Pd(OAc) 2 (4 mol %) was added to a solution of 45 mmol of iodoarene 2a-2d in 5 mL of DMF under an argon atmosphere. The reaction mixture 2-Methyl-5-styryl-2H-tetrazoles

Hydroarylation of (E)-5-(2-Arylethenyl)-2-methyl-2H-tetrazoles under Superelectrophilic Activation

“…Starting 5-(2-arylethenyl)-2-methyl-2H-tetrazoles 1a-e were synthesized and characterized by us previously. 21…”