X NO2 NH Z X NO2 N Z R Br R ( a) ( b) ( a) Z = Ph: NaOH–K2CO3–BTAC–benzene, heat ( b) Z = 4-Me-C6H4SO2, COMe: K2CO3–BTAC–acetone Z = Ph, 4-Me-C6H4SO2: SnCl2–Zn–HCl–AcOH 1 Z = COMe: Fe–EtOH–AcOH X NH2 N Z R 2 X N N Me R 4 X N2 + N Z R i, NaNO2–HCl ii, NaN3 h-j X N3 N Z R X N N N N R Z benzene heat H Ph H H Ph Me H Ph Ph Cl Ph H Cl Ph Me Cl Ph Ph Cl Ph 4-Me-C6H4SO2 H COMe H H COMe Me H COMe Ph a b c d e f g h i j XZ R 3 5 380 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 380 J.Chem. Research (M), 1997, 2215–2226 Intramolecular Azide Cycloadditions leading to [1,2,3]Triazolo[1,5-a]quinoxalines Gianluigi Broggini, Luisa Garanti, Giorgio Molteni* and Gaetano Zecchi Dipartimento di Chimica Organica e Industriale dell’Universit`a and Centro CNR, Via Golgi 19, 20133, Milano, Italy A general synthetic route to the title heterocyclic compounds has been developed based on the title reaction. We report here the synthesis of a variety of [1,2,3]triazolo[ 1,5-a]quinoxalines6,7 based upon the intramolecular cycloaddition of suitably functionalised aryl azides.As illustrated in the Scheme, our synthetic sequence involves the following steps: (i) preparation of N-substituted N-(2-alkynyl)-o-nitroanilines 1; (ii) reduction of their nitro group to a primary amino group; (iii) diazotisation of the so-formed anilines 2 and subsequent reaction with sodium azide to form the desired azidoderivatives 3; (iv) heat treatment of 3 in order to promote the intramolecular cycloaddition onto the acetylenic bond (see Table 1).Techniques used: IR, 1H NMR, mass spectrometry References: 11 Tables 2–5: Physical and spectral data for compounds 1b–j, 2b–j, 3, 4h, j and 5 Table 6: Elemental analyses of new compounds Received, 30th January 1997; Accepted, 23rd June 1997 Paper E/7/00705A References cited in this synopsis 6 J. C. Kauer and R. A. Carboni, J. Am. Chem. Soc., 1967, 89, 2633. 7 E. Lippmann and M. Vogel, Stud. Org. Chem. (Amsterdam), 1988, 35, 394. *To receive any correspondence (e-mail: garanti@icil64.cilea.it). Table 1 Reaction of azides 3a Reaction time Products and yields (%) Substrate (t/h) 5 Eluent 3a 3b 3c 3d 3e 3f 3g 3h 3i 3j 4 12 54441.5 1.5 21 4 80 63 76 60 60 67 78 91 80 96 — Et2O–CH2Cl2 (1:5) ———— AcOEt–Light petroleumb (1:1) Et2O–CH2Cl2 (1:5) CH2Cl2–Light petroleumb (5:1) aRefluxing in benzene solution (0.05 M). bBp 40–60 °C. Scheme