Benzazoles: III. Synthesis and Transformations of 6-(Chlorosulfonyl)-1,3-benzothiazol-2(3 H )-ones
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azoles: III.1 Synthesis and Transformations of 6-(Chlorosulfonyl)-1,3-benzothiazol-2(3H)-ones D. A. Dushamova,*, Yu. R. Takhirova, R. Sh. Kuryazova, and N. S. Mukhamedovb a b
Urgench State University, Urgench, 220100 Uzbekistan
Yunusov Institute of the Chemistry of Plant Substances, Tashkent, 100170 Uzbekistan *e-mail: [email protected] Received May 18, 2020; revised June 1, 2020; accepted June 9, 2020
Abstract—Treatment of 1,3-benzothiazol-2(3H)-one and its 3-methyl derivative with chlorosulfonic acid afforded the corresponding 2-oxo-2,3-dihydro-1,3-benzothiazole-6-sulfonyl chlorides which reacted with water, alcohols, and amines to give 2-oxo-2,3-dihydro-1,3-benzothiazole-6-sulfonic acids and their esters and amides. Keywords: 2-oxo-2,3-dihydro-1,3-benzothiazole-6-sulfonamides, 2-oxo-2,3-dihydro-1,3-benzothiazole-6-sulfonic acid esters, 2-oxo-2,3-dihydro-1,3-benzothiazole-6-sulfonic acids, 2-oxo-2,3-dihydro-1,3-benzothiazole6-sulfonyl chlorides, electrophilic substitution, nucleophilic substitution
DOI: 10.1134/S1070428020090031 Benzothiazole derivatives have attracted much interest due to their high biological activity and broad spectrum of action [2–5]. In particular, compounds exhibiting fungicidal [2], herbicidal [3], growthstimulating [4], and defoliating activities [5] were found among benzothiazole derivatives. In continuation of out studies on electrophilic substitution in the series of nitrogen heterocycles [6–11], herein we report chlorosulfonation of 1,3-benzothiazol-2(3H)-one (1a) and 3-methyl-1,3-benzothiazol-2(3H)-one (1b) and some chemical transformations of their chlorosulfonyl derivatives.
Compounds 1a and 1b reacted with chlorosulfonic acid to give the corresponding 6-chlorosulfonyl derivatives 2a and 2b, regardless of the reactant ratio. The best yields of 2a and 2b (83 and 87%, respectively) were obtained using 5 equiv of chlorosulfonic acid (Scheme 1). It should be noted that intermediate 2-oxo2,3-dihydro-1,3-benzothiazole-6-sulfonic acids 3a and 3b could not be isolated. Presumably, the hydroxy group on the sulfur atom is readily replaced by chlorine due to increased positive charge on the sulfonyl sulfur atom. Sulfonic acids 3a and 3b were obtained with high yields by hydrolysis of 2a and 2b, respectively. In
Scheme 1. O
O S
HO
O
S
S O
N
N
R
R
1a, 1b ClSO3H 50–60°C, 2 h 83–87%
3a, 3b O
O Cl
S
H2O, 100°C, 2 h 91–92%
S O N R 2a, 2b
1–3, R = H (a), Me (b). 1
For communication II, see [1].
1519
ClSO3H 50–60°C, 1 h 96–98%
1520
DUSHAMOV et al. Scheme 2.
R2
O
O N
S
S O
R2
R22NH, Me2CO 20°C, 2 h
O
O Cl
S
S O
64–82%
N
R 3O
S
S O
64–68%
N
R1
O
O
R3OH, Me2CO 20°C, 2 h
N
R1
4a–4h
R1
2a, 2b
5a–5d
2, R = H (a), Me (b); 4: R1 = H (a, b, e, f), Me (c, d, g, h); R2 = Et (a, c), Bu (b, d); R22N = piperidin-1-yl (e, g), morpholin-4-yl (f, h); 5, R1 = H (a, b), Me (c, d); R3 = Me (a, c), Et (b, d).
turn, sulfonic acids 3a and 3b were smoothly and quantitatively converted to sulfonyl chlorides 2a and 2b by treatment with chlorosulfonic acid (Scheme 1). S
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