Synlett 2020; 31(18): 1813-1816
DOI: 10.1055/s-0040-1706470
letter

Synthesis of 2-Arylbenzothiazol-5-amines from N,N-Dialkyl-3-nitroanilines

Hang T. Pham
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
,
Tuan H. Ho
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
,
Duy Q. Do
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
,
Kim L. H. Nguyen
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
,
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
,
a   Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam   eMail: tungtn@hcmut.edu.vn   eMail: ptsnam@hcmut.edu.vn
b   Vietnam National University, Ho Chi Minh City, Vietnam
› Institutsangaben
The Vietnam National University – Ho Chi Minh City (VNU-HCM) is acknowledged for financial support through project No. NCM2019-20-01.


Abstract

We report a simple method for coupling of N,N-dialkyl-3-nitroarenes, elemental sulfur, and activated sp3 C–H bonds in 2-methylazaarenes or arylacetic acids to afford derivatives of 2-arylbenzothiazol-5-amines. Only DABCO base was required, and many heterocycles such as imidazoles, oxazoles, quinolines, and thiophenes were compatible with the reaction conditions. Our approach offers a simple route to useful substituted thiazol-5-amines from commercially available nitroarenes.

Supporting Information



Publikationsverlauf

Eingereicht: 14. Juli 2020

Angenommen nach Revision: 14. August 2020

Artikel online veröffentlicht:
09. September 2020

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  • 10 N,N-Dimethyl-2-(6-methylpyridin-2-yl)-1,3-benzothiazol-5-amine (3ab); Typical Procedure An 8 mL screw-cap vial was charged with nitroaniline 1a (0.5 mmol, 83.0 mg), 2,6-dimethylpyridine (2b; 1.0 mmol, 107.0 mg), elemental sulfur (1 mmol, 32 mg), and DABCO (0.375 mmol, 42 mg). The vial was capped, flushed with a strong flow of argon for 5 min, and placed in a preheated bath at 120 °C for 16 h. The mixture was then cooled to r.t. and H2O (3 mL) was added. The organic components were then extracted into EtOAc (3 × 5 mL). The combined organic extracts were dried (Na2SO4), filtered, concentrated in vacuo, and purified by column chromatography [silica gel, hexanes–EtOAc (gradient 20:1 to 3:1)] to give an orange solid; yield: 113.5 mg (84%); mp 127–130 °C; Rf = 0.37 (hexanes–EtOAc, 3:1). 1H NMR (500 MHz, DMSO-d 6): d = 8.07 (d, J = 7.5 Hz, 1 H), 7.91–7.85 (m, 2 H), 7.41 (d, J = 7.5 Hz, 1 H), 7.30 (s, 1 H), 7.04 (d, J = 8.5 Hz, 1 H), 2.99 (s, 6 H), 2.57 (s, 3 H). 13C NMR (126 MHz, DMSO-d 6): d = 169.2, 158.4, 155.6, 150.1, 150.0, 137.8, 125.2, 123.2, 122.1, 117.2, 113.7, 105.0, 40.6, 23.9. HRMS (ESI+): m/z [M + H]+ calcd for C15H16N3S+: 270.1059; found: 270.1061.