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Synlett 2006(4): 0627-0629  
DOI: 10.1055/s-2006-926247
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Resourceful Access to α-Functionalized Arylhydrazones

Muhammad Usman Anwara, Sonja Traglb,, Thomas Ziegler*a, Lakshminarayanapuram R. Subramanian*a
a Institut für Organische Chemie, Lehrstuhl II, Auf der Morgenstelle 18, 72076 Tübingen, Germany
Fax: +49(7071)2952244; e-Mail: l.r.subramanian@t-online.de; e-Mail: thomas.ziegler@uni-tuebingen.de;
b Institute für Anorganische Chemie, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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Publication History

Received 5 December 2005
Publication Date:
20 February 2006 (online)

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Abstract

Several compounds containing active methylene groups flanked by carbonyl, cyano or nitro groups were reacted with N-nonaflylbenzotriazole (BtNf, 1) at room temperature. An instantaneous reaction took place, which was complete within 10-30 minutes. All active methylene compounds gave hydrazono derivatives by the attack of the carbon nucleophile at the nitrogen in position 2 of the BtNf followed by ring-opening, thus providing a new access to α-functionalized arylhydrozones.

Key words

arylhydrazones - ring-opening - nonaflone - benzo­triazole

1

Crystal structure.

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Typical Procedure:
NaH (24 mg, 60% suspension in oil) was added to a stirred solution of diethyl malonate (160 mg, 1 mmol) and 1 (401 mg, 1 mmol) in anhyd toluene (50 mL) at r.t. under argon. The mixture was allowed to stir for 30 min while controlling the progress of reaction by TLC. At the end of this period, EtOAc (100 mL) and H2O (25 mL) were added, and the suspension was treated with concd HCl. The organic phase was separated, dried (Na2SO4), filtered, and solvent was evaporated. The crude product was purified by recrystallization from PE (bp 60-90 °C) to give pure 3.

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Compound 3: yield 460 mg (82%); mp 89-90 °C (PE). UV/Vis (MeCN): λmax (ε = mol-1 dm3 cm-1) = 233 (8929), 343.50 nm(15521). 1H NMR (400 MHz, CDCl3): δ = 12.99 (s, 1 H, NH), 10.75 (s, 1 H, NH), 7.77 (d, J = 8.08 Hz, 1 Harom), 7.22-7.27 (m, 1 Harom), 7.14-7.18 (m, 1 Harom), 7.07-7.10 (m, 1 Harom) 4.34-4.44 (m, 4 H, CH2), 1.42 (t, J = 8.00 Hz, 3 H, CH3), 1.34 (t, J = 8.00 Hz, 3 H, CH3). 13C NMR (400 MHz, CDCl3): δ = 14.00, 62.10, 118.60, 124.00, 125.60, 125.13, 127.00, 131.00, 161.37, 163.40. MS (FAB): m/z = 562.00 [M+ + 1]. Anal. Calcd for C17H16F9N3O6S: C, 36.37; H, 2.87; N, 7.49; S, 5.71. Found: C, 35.85; H, 2.81; N, 7.27; S, 5.25.

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As an example, compound 5: yield 421 mg (84%); mp 118-119 °C (PE). UV/Vis (MeCN): λmax (ε = mol-1 dm3 cm-1) = 243.50 (12455), 357 nm(15331). 1H NMR (400 MHz, CDCl3): δ = 15.11 (s, 1 H, NH), 7.59-7.61 (m, 1 Harom), 7.40-7.44 (m, 1 Harom), 7.22-7.26 (m, 1 Harom), 7.53 (d, J = 8.08 Hz, 1 Harom) 2.53 (s, 3 H, CH3), 2.47 (s, 3 H, CH3). 13C NMR (400 MHz, CDCl3): δ = 26.69, 31.65, 118.00, 123.25, 126.22, 127.35, 129.45, 133.89, 136.21, 196.83, 198.54. MS (FAB): m/z = 502 [M+ + 1]. Anal. Calcd for C15H12F9N3O4S: C, 35.94; H, 2.41; N, 8.38; S, 6.40. Found: C, 36.10; H, 2.39; N, 8.47; S, 6.39.

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As an example, compound 6: yield 421 mg (82%); mp 169-170 °C (PE-EtOAc). UV/Vis (MeCN): λmax (ε = mol-1 dm3 cm-1) = 246 (9883), 387.50 nm (11819). 1H NMR (400 MHz, acetone-d 6): δ = 15.35 (s, 1 H, NH), 7.92 (d, J = 8.32 Hz, 1 Harom), 7.54-7.60 (m, 2 Harom), 7.33-7.40 (m, 1 Harom), 5.62 (s, 1 H, =CH) 2.78 (t, J = 6.32 Hz, 2 H, COCH2), 2.68 (t, J = 6.44 Hz, 2 H, HCOCH2), 2.11 (m, 2 H, COCH2CH 2). 13C NMR (400 MHz, acetone-d 6): δ = 19.00, 55.00, 39.60, 118.40, 123.64, 127.14, 130.20, 131.20, 140.00, 199.00, 193.40. MS (FAB): m/z = 514 [M+ + 1]. Anal. Calcd for C16H12F9N3O4S: C, 37.44; H, 2.36; N, 8.19; S, 6.25. Found: C, 37.63; H, 2.39; N, 8.04; S, 6.18.

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CCDC No. 294289 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 (1223)336033; or deposit@ccdc.cam.ac.uk].

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We thank one of the referees for pointing out this interesting possibility.