2‐(2‐Hydroxyphenyl)‐5‐aminothiazoles: Synthesis and Properties Involving Dual Emissions

Abstract

2-(2-Hydroxyphenyl)-5-aminothiazoles were prepared by two different methods to elucidate their photophysical properties. The first synthetic method involved the addition of thioamide dianions derived from secondary thioamides and nBuLi to thioforamides. Alternatively, Pdcatalyzed sequential addition of aromatic groups and diarylamines to commercially available thiazoles led to the precursors of the desired thiazoles. The molecular structures of the resulting thiazoles were determined by X-ray analyses. The thiazoles showed dual-emission in cyclohexane and in the solid state.[a] Prof.

Two Approaches for the Synthesis of Fused Dihydropyridines via a 1,6-Electrocyclic Reaction: Fluorescent Properties and Prospects for Application

“…The 1 H and 13 C NMR spectra, EI-TOF-MS spectra, and Fourier transform infrared (FT-IR) spectra were consistent with those of the structures expected for compounds 8 (see the Experimental Section and Figures S6−S15). Signals corresponding to the CH protons of the heterocyclic core were observed in the 1 H NMR spectrum of compound 8a as a doublet of C(4)H doublets in the region of 6.02 ppm, whereas a doublet of C(5)H doublets of protons at 5.90 ppm and a doublet of doublets C(6) H at 6.23 ppm were observed with the corresponding constant.…”

“…1 H NMR and 13 C NMR spectra were recorded with a Bruker Avance II (Karlsruhe, Germany) (400 MHz for 1 H, 100 MHz for 13 C) spectrometer. Chemical shifts are reported in parts per million (ppm) relative to TMS in 1 H NMR and to the residual solvent signals in 13 C as an external reference. Coupling constant (J) values are given in hertz (Hz).…”

“…2-Cyano-5-phenylpenta-2,4-dienethioamide (3a): Prepared according to GP-A; orange powder (2.033 g, 95% yield); mp = 166−167 °C; 1 H NMR (DMSO-d 6 , 400 MHz) δ 9.96 (br s, 1H), 9.45 (br s, 1H), 7.97 (d, 1H, J = 11.2 Hz), 7.71 (m, 2H), 7.47 (m, 4H), 7.17 (dd, 1H, J = 11.2, J = 15.4 Hz); 13 2-Cyano-5-(4-(dimethylamino)phenyl)penta-2,4-dienethioamide (3c): Prepared according to GP-A; dark red powder (2.107 g, 82% yield); mp = 230−232 °C; 1 H NMR (DMSO-d 6 , 400 MHz) δ 9.67 (br s, 1H), 9.13 (br s, 1H), 7.98 (d, 1H, J = 11.5 Hz), 7.51 and 6.72 (AA′XX′, 4H, J = 8.9 Hz), 7.34 (d, 1H, J = 14.9 Hz), 6.88 (dd, 1H, J = 14.9, J = 11.6 Hz), 3.00 (s, 6H); 13 Methyl-2-(8-cyano-5-(2-methoxyphenyl)-3-oxo-5H-thiazolo[3,2a]pyridin-2(3H)-ylidene)acetate (8d): Prepared according to GP-B; after column chromatography (methylene chloride), an orange powder (0.134 mg, 38% yield) was obtained; mp = 182−184 °C; 1 H NMR (DMSO-d 6 , 400 MHz) δ 7.30 (t, 1H, J = 7.8 Hz), 7.10 (dd, 1H, J = 7.5 Hz, J = 1.0 Hz), 7.06 (d, 1H, J = 8.2 Hz), 6.94 (t, 1H, J = 7.4 Hz), 6.75 (s, 1H), 6.17 (dd, 1H, J = 4.2 Hz, J = 0.9 Hz), 6.14 (dd, 1H, J = 9.9 Hz, J = 1.3 Hz), 5.79 (dd, 1H, J = 9.8, 4.5 Hz), 3.81 (s, 6H); 13…”

“…Thioamides are building blocks widely used for the synthesis of nitrogen- and sulfur-containing heterocyclic compounds. − Thioamides can react with various monoelectrophilic, dielectrophilic, and ambient agents, such as α-halocarbonyl compounds and alkyl and alkenyl dihalides. − The CS bond of a thioamide group may react as a dienophile component in [4 + 2] cycloaddition reactions − and as a dipolarophile in the thermal and catalytic variants of 1,3-dipolar cycloaddition reactions. ,, Moreover, α-diazothioacetamides easily transform into 1,2,3-thiadiazoles by a 1,5-electrocyclic reaction. ,− …”

“…J = 9.8 Hz), 5.96 (d, 1H, J = 4.4 Hz), 5.86 (dd, 1H, J = 9.8, 4.6 Hz), 4.26 (q, 2H, J = 7.0 Hz), 3.73 (s, 3H), 1.26 (t, 3H, J = 7.1 Hz);13 C{1H} NMR (DMSO-d 6 , 100 MHz) δ 165.6, 163.1, 159.3, 147.2, 138.4, 130.9, 128.5, 123.2, 116.2, 116.1, 115.5, 114.2, 84.0, 61.7, 57.5, 55.1, 13.9; FT-IR (neat) ν max (cm −1 ) 3063, 2992, 2960, 2904, 2838, 2211, 1705, 1683; HRMS (ESI-TOF) m/z [M + H] + calcd for C 19 H 18 N 2 O 4 SH 369.0904; found 369.0905; HRMS (ESI-TOF) m/z [M + H] + calcd for C 19 H 16 N 2 O 4 SH 369.0904; found 369.0905; [M + Na] + calcd for C 19 H 16 N 2 O 4 SNa 391.0723; found 391.0726; [M + K] + calcd for C 19 H 16 N 2 O 4 SK 407.0462; found 407.0460. 48% yield) was obtained; mp = 188−190 °C; 1 H NMR (DMSO-d 6 , 400 MHz) δ 7.30 (t, 1H, J = 7.9 Hz), 7.10 (dd, 1H, J = 7.6 Hz, J = 1.4 Hz), 7.06 (d, 1H, J = 8.2 Hz), 6.94 (t, 1H, J = 7.4 Hz), 6.73 (s, 1H), 6.17 (dd, 1H, J = 4.3 Hz, J = 1.4 Hz), 6.13 (dd, 1H, J = 9.8 Hz, J = 1.5 Hz), 5.79 (dd, 1H, J = 9.8, 4.5 Hz), 4.28 (q, 2H, J = 7.1 Hz), 3.82 (s, 3H), 1.27 (t, 3H, J = 7.1 Hz); 13 C{ 1 H} NMR (DMSO-d 6 , 100 MHz) δ 165.3, 162.6, 155.8, 147.5, 137.9, 129.3, 126.7, 121.6, 120.7, 116.2, 115.7, 115.2, 111.6, 83.8, 61.4, 55.6, 54.4; FT-IR (neat) ν max (cm −1 ) 3066, 2996, 2970, 2938, 2838, 2204, 1709, 1688; HRMS (ESI-TOF) m/z [M + H] + calcd for C 19 H 16 N 2 O 4 SH 369.0904; found 369.0911; [M + Na] + calcd for C 19 H 16 N 2 O 4 SNa 391.0723; found 391.0731; [M + K] + calcd for C 19 H 16 N 2 O 4 SK 407.0462; found 407.0471.…”