Synlett 2016; 27(03): 399-403
DOI: 10.1055/s-0035-1560502
letter
© Georg Thieme Verlag Stuttgart · New York

A Base-Free Multicomponent Domino Approach: One-Pot Synthesis of 2-Iminothiazolines via Oxy-Iodination of Arylacetylenes

G. Santosh Kumar
Medicinal Chemistry and Pharmacology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad, Telangana 500007, India   Email: hmmeshram@yahoo.com
,
A. Sanjeeva Kumar
Medicinal Chemistry and Pharmacology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad, Telangana 500007, India   Email: hmmeshram@yahoo.com
,
H. M. Meshram*
Medicinal Chemistry and Pharmacology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad, Telangana 500007, India   Email: hmmeshram@yahoo.com
› Author Affiliations
Further Information

Publication History

Received: 27 May 2015

Accepted after revision: 03 September 2015

Publication Date:
20 November 2015 (online)


Abstract

A simple and an efficient multicomponent domino protocol is developed for the synthesis of 2-iminothiazolines starting from simple and readily available arylacetylenes, amines, and phenyl isothiocyanates under base-free conditions. The present method involves oxy-iodination­ of the arylacetylenes with ammonium iodide and hydrogen peroxide, followed by cyclization processes. A number of diversely functionalized 2-iminothiazolines are synthesized in good to excellent yields.

Supporting Information

 
  • References and Notes

    • 1a Nagasaki F, Yamada T, Takahashi E, Kitagawa Y, Hatano R. JP 63250371, 1988 ; Chem. Abstr. 1989, 110, 192810
    • 1b Hoelzel H, Creuzburg D, Stohr P, Dehne H, Teller J, Kranz L, Luthardt H, Roethling T, Kaestner A. DD 258168, 1988 ; Chem. Abstr. 1989, 111, 2681g.
  • 4 Murru S, Singh CB, Kavala V, Patel BK. Tetrahedron 2008; 64: 1931
  • 9 Narender N, Reddy KS. K, Krishna Mohan KV. V, Kulkarni SJ. Tetrahedron Lett. 2007; 48: 6124
  • 10 Thiazol-2-imines 4; General Procedure A 30% aq solution of H2O2 (2.2 mmol) was added dropwise to a vigorously stirred solution of NH4I (2.2 mmol) and arylacetylene 1 (1 mmol) in AcOH (3 mL), and the resulting mixture was allowed to stir at r.t. After 6 h, amine 2 and isothiocyanate 3 were added and the mixture was stirred at 70 °C for 1 h. After completion of the reaction, the mixture was filtered, and the filtrate treated with aq Na2S2O3 solution and then extracted with EtOAc. The combined organic layer was dried over Na2SO4 and evaporated under reduced pressure. Purification by column chromatography (hexane–EtOAc, 9.5:0.5) furnished the corresponding thiazol-2-imine 4. All the obtained products were characterized from their IR, 1H NMR, 13C NMR, MS and HRMS spectral data. (Z)-N-[4-(4-Fluorophenyl)-3-phenylthiazol-2(3H)-ylidene]aniline (4b) Yield: 249.20 mg (72%); pale yellow solid; mp 172–174 °C. IR (KBr): 703, 752, 1099, 1267, 1402, 1589, 1621 cm–1. 1H NMR (300 MHz, CDCl3): δ = 5.92 (s, 1 H), 6.88 (t, J = 8.54 Hz, 2 H), 6.99–7.10 (m, 5 H), 7.22–7.27 (m, 3 H), 7.28–7.35 (m, 4 H). 13C NMR (75 MHz, CDCl3): δ = 97.1, 115.2 (d, 2 J C–F = 21.7 Hz), 121.5, 123.2, 127.6, 127.7 (d, 4 J C–F = 2.7 Hz), 128.8, 128.9, 129.3, 129.9 (d, 3 J C–F = 8.1 Hz), 137.7, 138.8, 151.7, 159.9, 162.4 (d, 1 J C–F = 248.8 Hz). MS (ESI): m/z = 347 [M + H]+. HRMS (ESI): m/z [M + H]+calcd for C21H16N2FS: 347.1012; found: 347.1004.
  • 11 For a review on 2-iminothiazolidines (i.e., compounds related to 2-iminothiazolines), see: D’hooghe M, De Kimpe N. Tetrahedron 2006; 62: 513