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in g free base was crystallized from eth an ol to give pure 3g (7.9 g, 60%); m .p. 204–208 °C.
For C12H9ClN2OS (264.7) calculated: 54.44% C, 3.43% H, 10.58% N; foun d: 54.72% C,
3.19% H, 10.71% N. IR: 995, 1 030, 1 250, 1 545. 1H NMR: 3.77 s, 3 H (CH3O); 6.97 d, 2 H,
J = 9 (arom . H); 7.76 d, 2 H, J = 9 (arom . H); 8.12 s, 1 H (H-3); 8.28 s, 1 H (H-5).
Dem eth ylation with An h ydrous Alum in um Ch loride (Meth od A) – Gen eral Procedure
A m ixture of th e startin g m eth oxy derivative (8 m m ol) an d xylen e (100 m l) was treated with
an h ydrous alum in um ch loride (2.7 g, 20 m m ol). Th e reaction m ixture was refluxed for 5 h
an d evaporated un der reduced pressure. Water was added to th e residue an d th e m ixture
was basified with 2 M solution of am m on ium h ydroxide. Th e resultin g precipitate was col-
lected by filtration an d crystallized from eth an ol to give yields of 55–60%. Com poun d 6
could be obtain ed after 48 h at room tem perature an d com poun d 7 after 40 m in reflux.
6-(4-Hydroxyphenyl)imidazo[2,1-b]thiazoline (4a ). Yield 58%, m .p. 280–282 °C. For
C
11H10N2OS (218.3) calculated: 60.53% C, 4.62% H, 12.83% N; foun d: 60.65% C, 4.88% H,
13.04% N. IR: 820, 1 270, 1 490, 1 545. 1H NMR: 3.86 t, 2 H, J = 7 (H-2); 4.16 t, 2 H, J = 7
(H-3); 6.72 d, 2 H, J = 8 (arom . H); 7.48 d, 2 H, J = 8 (arom . H); 7.49 s, 1 H (H-5); 9.35 s, 1 H
(OH).
6-(3-Hydroxyphenyl)imidazo[2,1-b]thiazoline (4b ). Yield 56%, m .p. 237–239 °C. For
C
11H10N2OS (218.3) calculated: 60.53% C, 4.62% H, 12.83% N; foun d: 60.35% C, 4.33% H,
12.75% N. IR: 965, 1 220, 1 475, 1 575. 1H NMR: 3.88 t, 2 H, J = 7 (H-2); 4.19 t, 2 H, J = 7
(H-3); 6.58 m , 1 H (arom . H); 7.09 m , 3 H (arom . H); 7.63 s, 1 H (H-5); 9.32 s, 1 H (OH).
6-(2-Hydroxyphenyl)imidazo[2,1-b]thiazoline (4c). Yield 60%, m .p. 165–169 °C. For
C
11H10N2OS (218.3) calculated: 60.53% C, 4.62% H, 12.83% N; foun d: 60.84% C, 4.58% H,
12.64% N. IR: 750, 830, 1 250, 1 580. 1H NMR: 3.80 t, 2 H, J = 7 (H-2); 4.15 t, 2 H, J = 7
(H-3); 6.90 m , 3 H (arom . H); 7.62 m , 1 H (arom . H); 7.72 s, 1 H (H-5); 11.13 s, 1 H (OH).
6-(3-Hydroxyphenyl)imidazo[2,1-b]thiazole (4e). Yield 59%, m .p. 207–211 °C. For
C
11H8N2OS (216.3) calculated: 61.09% C, 3.73% H, 12.95% N; foun d: 61.37% C, 3.94% H,
12.66% N. IR: 1 155, 1 175, 1 215, 1 590. 1H NMR: 6.66 m , 1 H (arom . H); 7.20 m , 3 H
(arom . H); 7.25 d, 1 H, J = 4.4 (H-2); 7.91 d, 1 H, J = 4.4 (H-3); 8.14 s, 1 H (H-5); 9.43 s, 1 H
(OH).
2-Chloro-6-(4-hydroxyphenyl)imidazo[2,1-b]thiazole (4g). Yield 60%, m .p. 185–189 °C. For
C
11H7ClN2OS (250.7) calculated: 52.70% C, 2.81% H, 11.17% N; foun d: 52.91% C, 2.63% H,
10.94% N. IR: 1 240, 1 260, 1 550, 1 610. 1H NMR: 6.78 d, 2 H, J = 8 (arom . H); 7.63 d, 2 H,
J = 8 (arom . H); 8.03 s, 1 H (H-3); 8.25 s, 1 H (H-5); 9.49 s, 1 H (OH).
6-(2-Hydroxy-5-methoxyphenyl)imidazo[2,1-b]thiazoline (6).Yield 58%, m .p. 227–230 °C. For
C
12H12N2O2S (248.3) calculated: 58.05% C, 4.87% H, 11.28% N; foun d: 57.86% C, 5.06% H,
11.49% N. IR: 1 155, 1 200, 1 265, 1 500. 1H NMR: 3.69 s, 3 H (CH3O); 3.93 t, 2 H, J = 7
(H-2); 4.25 t, 2 H, J = 7 (H-3); 6.64 dd, 1 H, J = 3, J = 8 (arom . H-4); 6.75 d, 1 H, J = 8 (arom .
H-3); 7.24 d, 1 H, J = 3 (arom . H-6); 7.80 s, 1 H (H-5); 10.46 s, 1 H (OH).
6-(2,5-Dihydroxyphenyl)imidazo[2,1-b]thiazoline (7). Yield 60%, m .p. 188–190 °C. For
C
11H10N2O2S (234.3) calculated: 56.40% C, 4.30% H, 11.96% N; foun d: 56.69% C, 4.12% H,
12.12% N. IR: 965, 1 195, 1 335, 1 480. 1H NMR: 3.94 t, 2 H, J = 7 (H-2); 4.26 t, 2 H, J = 7
(H-3); 6.45 dd, 1 H, J = 3, J = 8 (arom . H-4); 6.62 d, 1 H, J = 8 (arom . H-3); 7.07 d, 1 H, J = 3
(arom . H-6); 7.71 s, 1 H (H-5); 8.72 s, 1 H (OH); 10.29 s, 1 H (OH).
Collect. Czech. Chem. Commun. (Vol. 65) (2000)