2-[4-Benzo[d]furan-2,1,3-thiazol-2-yl)]Ethane-Nitrile
2305
α-substituted cinnamonitrile reacted with 3 in ethanol containing a
catalytic amount of piperidine gave a product identical in all respects
(m.p., mixed m.p., and spectra) with 4. The formation of 4 can be ex-
plained by the addition of cinnamonitrile to 3 via the Micheal addition to
give the adduct intermediate 7 followed by elimination of malononitrile
(or ethyl cyanoacetate), respectively, to give final product 4 (Scheme 1).
Compound 3 reacted with phenyl isothiocyanate in N,N-dimethyl-
formamide containing potassium hydroxide, which acidifies with acetic
acid, to afford thioanilide 8 (Scheme 1). Compound 8 was confirmed on
the basis of elemental analysis, IR, and 1H-NMR, and chemical transfor-
mation. Thus, compound 8 reacted with chloroacetone in the presence
1
of potassium hydroxide to give S-acetonyl derivative 9. H NMR spec-
trum of 9 showed signals at δ = 2.64 (s, 3H, CH3), 3.34 (s, 2H, CH2),
–1
6.86 (s, 1H, CH thiazole) and 7.43–7.94 (m, ArH’s and NH). Its IR (cm
)
spectrum revealed bands at 3433 (NH), 2175 (CN), 1705 (CO), and 1600
(C N).
Compound 9 was conversted to thiazole derivative 10 by heating in
ethanol containing a catalytic amount of piperidine. 1H NMIR showed
signals at δ = 2.79 (s, 3H), 6.49 (s, 1H), 7.02 (s, 1H), and 7.25–7.96 (m,
9H, ArH’s). Its IR (cm–1) spectrum revealed bands at 2167 (CN), 1640
(C N), and 1600 (C C).
Ethyl chloroacetate reacted with thioanilide derivative 9 in N,N-
dimethylformamide containing potassium hydroxide at room tempera-
ture to give 11. Compound 11 was confirmed on the basis of elemental
analysis and spectral data and converted to aminothiophene 12 by boil-
1
ing in ethanol containing a catalytic amount of piperidine. HNMR (δ
ppm) spectrum 11 showed signals at δ = 1.22 (t, 3H, CH3 ester), 2.66,
3.34 (s, 2H, SCH2), 4.11 (q, 2H, CH2CH3), and 7.22–791 (m, 9H, (s, Ar.,
–1
1H, NH). Its IR (cm ) revealed bands at 3440 (NH), 2923 (CH), 2190
1
(CN), 1743 (CO), and 1620 (C N). H-NMR (δ ppm) spectrum of 12
showed signals at δ = 1.35 (t, 3H, CH3 CH2), 4.27 (q, 2H, CH2), 6.10
(s, 2H, NH2), 7.19–7.98 (m, 10H, ArH’s) and 11.51 (s, br., 1H, NH). Its
–1
IR (cm ) revealed bands at 3394, 3301, 3290 (NH2, NH), 1710 (CO),
1645 (C N), and 1600 (C C).
Treatment of the appropriate hydrazonoyl halides 13a–c with
thioanilide 8 in N,N-dimethylformamide containing potassium hydrox-
ide gave a single product (tlc) in each case. IR (cm–1) spectra of the
corresponding products showed bands near 2921 (CN) and 1728 and
1689 (CO’s) 1H NMR spectrum of 14a showed signals at δ = 1.47 (t, 3H,
CH3CH2) 4.49 (q, 2H, CH2 ester), 7.15 (s, 1H, thiazole and 7.26–8.02
1
(m, 9H, Ar H). H NMR spectrum of 14b showed signals at δ = 1.47
(t, 3H, CH2CH3), 2.48 (s, 3H, 4/CH3C6H4), 4.40 (q, 2H, CH2CH3), 7.15
(s, 1H, thiazole C-5), and 7.26–8.02 (m, 9H, ArH). On the above-finding