Open Access Published by De Gruyter June 27, 2017

Halogenoheterocyclization of terminally substituted 2-allylthio(seleno)quinolin- 3-carbaldehydes

Mikhajlo Onysko, Igor Filak and Vasyl Lendel

Abstract

Electrophilic heterocyclization of 2-alkenyllthioquinolin-3-carbaldehydes or 2-alkenylselenoquinolin-3-carbaldehydes 2, 3 under the action of iodine or bromine non-regioselectively leads to the formation of fused quinolinium trihalogenides 4, 5. Type of the chalcogen atom does not affect regiochemistry of halogenation.

Introduction

Electrophilic haloсyclization of unsaturated thioethers of heterocycles is a convenient method for annellation of heterocycles and formation of condensed polycyclic compounds [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20]. Regioselectivity of heterocyclization may be controlled by steric factors, nature of unsaturated alkenyl or alkynyl moiety [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], nature of electrophile [18] and by the presence of additional nucleophilic centers [7], [8], [9], [19], [20].

Results and discussion

In our previous studies, it was indicated that halocyclization of terminal non-substituted 2-allylthio(oxy)quinoline carbaldehydes leads to the formation of a fused thiazoline(oxazoline) system [14], [15], [16]. The purpose of this study is to examine the impact of aryl and alkyl substituents at the terminal carbon atom in an allyl fragment on regioselectivity of halocyclization. The 2-cynnamylthio(seleno)-3-carbaldehydes and 2-(3-methyl-2-butenylthio(seleno)quinoline-3-carbaldehydes 2,3 were used as model substrates (Scheme 1). These compounds were obtained by alkylation of quinolines 1 in an alkaline medium [14], [15]. Bromination and iodination of the terminally substituted thio(seleno)ethers 2,3 were carried out in chloroform with a two-fold excess of halogen. It was found that cyclization of thio(seleno)ethers 2a–c leads to the formation of thiazino(selenazino)[3,2-a]quinolinium trihalohenides 4a–d, while the cyclization of thio(seleno)ethers 3a–c results in the formation of thiazolo(selenazolo)[3,2-a]quinolinium trihalohenides 5a–d. The yields of selenazino[3,2-a]quinolinium triiodide 4d (54%) and selenazolo[3,2-a]quinolinium tribromide 5d (45%) are lower than the yields of the corresponding thiazino 4a–c (67%–71%) and thiazolo analogues 5a–c (70%–74%). This outcome may be caused by greater solubility of 4d and 5d in chloroform.

Scheme 1

Scheme 1

It can be suggested that polarization of a multiple bond and steric factors affect the regioselectivity of electrophilic heterocyclization of terminally substituted propenyl thioethers of quinoline-3-carbaldehyde. Spectral data confirm the formation of trihalohenides 4,5. Annellation to a thiazine or selenazine system upon halogenation of unsaturated thio(seleno)ethers 2a–c is consistent with the literature data [4], [7], [8], [9], [18]. However, in contrast to the first report [4], which indicates the formation of a thiazine, the cyclization of thio(seleno)ethers 3a–c leads to annellation to the thiazoline or selenazoline. This fact is fully confirmed by analysis of chemical shifts of a methine group in 1H NMR and 13C NMR spectra, that are observed at 6.59-9-6.64 ppm (1H NMR) and 68 ppm (13C NMR) for compounds 5a–d. These spectral data are in good agreement with the previously reported values for thiazolinoquinolines [14].

Conclusions

Halocyclization of terminally substituted allylthioethers or allylseleno analogues of quinoline-3-carbaldehydes leads to the formation of regioisomers depending on the type of substituents – alkyl or aryl. The type of chalcogen atom does not affect regiochemistry.

Experimental

1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were recorded in DMSO-d6 on a Varian Mercury-400 instrument. Melting points were determined on a Stuart SMP30 instrument. Elemental analyses were performed on an Elementar Vario MICRO cube analyzer. All reagents were obtained from commercial suppliers and used without any further purification. Dry solvents were prepared according to the standard methods. 3-Formylquinolin-2-thiones 1a,b were synthesized as previously described [21]. Formylquinolin-2-selenone 1c was synthesized according to reference [22].

General method for synthesis of thioethers and selenoethers 2, 3

A solution of potassium hydroxide (0.012 mol) in water (5 mL) was added to a solution of thione 1a,b or selenone 1c (0.01 mol) in ethanol or isopropanol (20 mL). The mixture was stirred and treated with an alkenylhalogenide (0.012 mol). The resultant precipitate was filtered and crystallized from ethanol.

2-(3-Phenyl-2-propenylsulfanyl)-3-quinolinecarbaldehyde (2a)

Yield 53%; mp 103–104°C; 1H NMR: δ 4.17 (d, J=7 Hz, 2H), 6.45–6.49 (m, 1H), 6.80 (d, J=15.6 Hz, 1H), 7.21 (d, J=7 Hz, 1H), 7.29 (t, J=7 Hz, 2H), 7.40 (d, J=7 Hz, 2H), 7.63 (t, J=7 Hz, 1H), 7.93 (t, J=7 Hz, 1H), 8.03 (d, J=8 Hz, 1H), 8.11 (d, J=8 Hz, 1H), 8.92 (s, 1H), 10.19 (s, 1H); 13C NMR: δ 32.1, 125.0, 125.9, 126.8, 127.1, 127.7, 128.2, 129.3, 130.3, 133.6, 134.2, 137.2, 146.1, 149.2, 158.1, 192.0. Anal. Calcd for C19H15NOS: C, 74.73; H, 4.95; N, 4.59. Found: C, 74.20; H, 4.75; N, 4.43.

7-Methyl-2-(3-phenyl-2-propenylsulfanyl)-3-quinolinecarbaldehyde (2b)

Yield 90%; mp 114–115°C; 1H NMR: δ 2.55 (s, 3H), 4.15 (d, J=7 Hz, 2H), 6.43–6.47 (m, 1H), 6.77 (d, J=16 Hz, 1H), 7.21 (d, J=7 Hz, 1H), 7.28 (t, J=7 Hz, 2H), 7.39 (d, J=7 Hz, 2H), 7.45 (d, J=8 Hz, 1H), 7.81 (s, 1H), 7.98 (d, J=8 Hz, 1H), 8.82 (s, 1H), 10.14 (s, 1H). Anal. Calcd for C20H17NOS: C, 75.21; H, 5.36; N, 4.39. Found: C, 75.08; H, 5.19; N, 4.28.

2-(3-Phenyl-2-propenylselanyl)-3-quinolinecarbaldehyde (2c)

Yield 43%; mp 95–96°C; 1H NMR: δ 4.14 (d, J=8 Hz, 2H), 6.51–6.54 (m, 1H), 6.73 (d, J=16 Hz, 1H), 7.18 (d, J=7 Hz, 1H), 7.27 (t, J=7 Hz, 2H), 7.36 (d, J=8 Hz, 2H), 7.67 (t, J=7 Hz, 1H), 7.95 (t, J=7 Hz, 1H), 8.09 (d, J=8 Hz, 1H), 8.15 (d, J=8 Hz, 1H), 8.96 (s, 1H), 10.18 (s, 1H). Anal. Calcd for C19H15NOSe: C, 64.79; H, 4.29; N, 3.98. Found: C, 64.92; H, 4.21; N, 3.81.

2-(3-Methyl-2-butenylsulfanyl)-3-quinolinecarbaldehyde (3a)

Yield 55%; mp 60–61°C; 1H NMR: δ 1.69 (s, 3H), 1.76 (s, 3H), 3.94 (d, J=8 Hz, 2H), 5.39 (t, J=7 Hz, 1H), 7.61 (t, J=7 Hz, 1H), 7.91 (m, 2H), 8.10 (d, J=8 Hz, 1H), 8.89 (s, 1H), 10.17 (s, 1H). Anal. Calcd for C15H15NOS: C, 70.01; H, 5.87; N, 5.44. Found: C, 69.83; H, 5.65; N, 5.31.

7-Methyl-2-(3-methyl-2-butenylsulfanyl)-3-quinolinecarbaldehyde (3b)

Yield 63%; mp 82–83°C; 1H NMR: δ 1.68 (s, 3H), 1.74 (s, 3H), 2.52 (s, 3H), 3.90 (d, J=8 Hz, 2H), 5.38 (t, J=8 Hz, 1H), 7.41 (d, J=8 Hz, 1H), 7.69 (s, 1H), 7.94 (d, J=8 Hz, 1H), 8.76 (s, 1H), 10.12 (s, 1H). Anal. Calcd for C16H17NOS: C, 70.82; H, 6.31; N, 5.16. Found: C, 70.56; H, 6.15; N, 5.01.

2-(3-Methyl-2-butenylselanyl)-3-quinolinecarbaldehyde (3c)

Yield 72%; mp 65–66°C; 1H NMR: δ 1.69 (s, 3H), 1.75 (s, 3H), 3.93 (d, J=8 Hz, 2H), 5.47 (t, J=7 Hz, 1H), 7.66 (t, J=7 Hz, 1H), 7.97 (m, 2H), 8.14 (d, J=8 Hz, 1H), 8.94 (s, 1H), 10.18 (s, 1H). Anal. Calcd for C15H15NOSe: C, 59.23; H, 4.97; N, 4.60. Found: C, 59.56; H, 4.76; N, 4.52.

General method for synthesis of compounds 4, 5

A solution of bromine or iodine (7.2 mmol) in chloroform was added to a solution of thio(seleno)ether 2 or 3 (3.6 mmol) in chloroform (15 mL) under constant stirring. After 5 h (for bromine) or 2 days (for iodine) the precipitated yellow or brown product was filtered and washed with chloroform.

5-Formyl-2-iodo-1-phenyl-2,3-dihydro-1H-[1,3]thiazino[3,2-a]quinolin-11-ium triiodide (4a)

Yield 69%; mp 168–170°C; 1H NMR: δ 4.30 (d, J=7 Hz, 2H), 5.87 (d, J=7 Hz, 1H), 6.78 (m, 1H), 7.11 (m, 3H), 7.42 (m, 2H), 7.79 (t, J=7 Hz, 1H), 7.98 (t, J=7 Hz, 1H), 8.07 (d, J=8 Hz, 1H), 8.37 (d, J=7 Hz, 1H), 9.68 (s, 1H), 10.28 (s, 1H); 13C NMR: δ 29.3, 37.6, 72.2, 126.1, 126.8, 129.2, 129.4, 129.5, 130.4, 132.4, 138.1, 138.3, 139.2, 152.8, 164.7, 190.0. Anal. Calcd for C19H15I4NOS: C, 28.07; H, 1.86; I, 62.44; N, 1.72. Found: C, 28.20; H, 1.78; I, 62.04; N, 1.68.

2-Bromo-5-formyl-1-phenyl-2,3-dihydro-1H-[1,3]thiazino[3,2-a]quinolin-11-ium tribromide (4b)

Yield 67%; mp 192–194°C; 1H NMR: δ 3.36 (d, J=15 Hz, 1H), 3.66 (d, J=15 Hz, 1H), 5.90 (d, J=3 Hz, 1H), 7.40–7.46 (m, 6H), 7.99 (t, J=7 Hz, 1H), 8.15–8.22 (m, 2H), 8.55 (d, J=8 Hz, 1H), 9.71 (s, 1H), 10.34 (s, 1H); 13C NMR: δ 31.0, 42.4, 66.6, 79.9, 118.1, 125.7, 126.7, 128.7, 129.2, 129.7, 130.5, 133.8, 135.6, 138.8, 141.4, 152.1, 163.3, 189.5. Anal. Calcd for C19H15I4NOS: C, 38.51; H, 2.42; Br, 51.14; N, 2.24. Found: C, 38.26; H, 2.50; Br, 50.89; N, 2.12.

5-Formyl-2-iodo-9- methyl-1-phenyl-2,3-dihydro-1H-[1,3]thiazino [3,2-a]quinolin-11-ium triiodide (4c)

Yield 71%; mp 165–167°C; 1H NMR: δ 2.54 (s, 3H), 4.30 (d, J=7 Hz, 2H), 5.79 (d, J=8 Hz, 1H), 6.79 (m, 1H), 7.03 (m, 3H), 7.35 (m, 2H), 7.57 (d, J=8 Hz, 1H), 7.83 (s, 1H), 8.18 (d, J=8 Hz, 1H),, 9.55 (s, 1H), 10.23 (s, 1H); 13C NMR: δ 22.8, 28.8, 37.8, 72.0, 119.9, 124.0, 125.8, 128.6, 129.2, 130.3, 130.8, 131.6, 138.3, 139.3, 150.0, 151.9, 163.7, 189.9. Anal. Calcd for C20H17I4NOS: C, 29.05; H, 2.07; I, 61.38; N, 1.69. Found: C, 28.91; H, 2.00; I, 61.43; N, 1.55.

5-Formyl-2-iodo-1-phenyl-2,3-dihydro-1H-[1,3]selenazino[3,2-a]quinolin-11-ium triiodide (4d)

Yield 54%; mp 173–175°C; 1H NMR: δ 4.35 (d, J=7 Hz, 2H), 5.93 (d, J=7 Hz, 1H), 6.81 (m, 1H), 7.13 (m, 3H), 7.40 (m, 2H), 7.80 (t, J=7 Hz, 1H), 7.99 (t, J=7 Hz, 1H), 8.05 (d, J=8 Hz, 1H), 8.35 (d, J=7 Hz, 1H), 9.67 (s, 1H), 10.28 (s, 1H); Anal. Calcd for C19H15I4NOSe: C, 26.54; H, 1.76; I, 59.04; N, 1.63. Found: C,26.21; H, 1.59; I, 58.84; N, 1.55.

1-(1-Bromo-1-methylethyl)-4-formyl-1,2-dihydro[1,3]thiazolo[3,2-a]quinolin-10-ium tribromide (5a)

Yield 70%; mp 145–147°C; 1H NMR: δ 1.74 (s, 3H), 1.83 (s, 3H), 4.20 (m, 1H), 4.31 (d, J=9 Hz, 1H), 6.64 (d, J=9 Hz, 1H), 7.94 (t, J=8 Hz, 1H), 8.24 (t, J=7 Hz, 1H), 8.50 (d, J=8 Hz, 1H), 8.68 (d, J=8 Hz, 1H), 9.74 (s, 1H), 10.24 (s, 1H); 13C NMR: δ 32.7, 33.0, 34.9, 68.4, 73.4, 121.8, 126.6, 129.4, 132.4, 137.3, 140.9, 153.2, 167.3, 189.9. Anal. Calcd for C15H15Br4NOS: C, 31.23; H, 2.62; Br, 55.40; N, 2.43. Found: C, 31.05; H, 2.50; Br, 55.08; N, 2.26.

1-(1-Iodo -1-methylethyl)-4-formyl-1,2-dihydro[1,3]thiazolo[3,2-a] quinolin-10-ium triiodide (5b)

Yield 74%; mp 115–117°C; 1H NMR: δ 1.89 (s, 3H), 1.92 (s, 3H), 4.31 (m, 1H), 4.36 (d, J=9 Hz, 1H), 6.59 (d, J=9 Hz, 1H), 7.96 (t, J=7 Hz, 1H), 8.25 (t, J=7 Hz, 1H), 8.50 (d, J=7 Hz, 1H), 8.67 (d, J=7 Hz, 1H), 9.72 (s, 1H), 10.26 (s, 1H). Anal. Calcd for C15H15I4NOS: C, 23.55; H, 1.98; I, 66.36; N, 1.83. Found: C, 23.32; H, 1.79; I, 66.41; N, 1.72.

1-(1-Bromo-1-methylethyl)-4-formyl-8-methyl-1,2-dihydro[1,3]thiazolo[3,2-a]quinolin-10-ium tribromide (5c)

Yield 73%; mp 128–130°C; 1H NMR: δ 1.73 (s, 3H), 1.84 (s, 3H), 2.69 (s, 3H), 4.19 (m, 1H), 4.29 (d, J=8 Hz, 1H), 6.59 (d, J=8 Hz, 1H), 7.80 (d, J=8 Hz, 1H), 8.38 (d, J=8 Hz, 1H), 8.56 (s, 1H), 9.66 (s, 1H), 10.22 (s, 1H). Anal. Calcd for C16H17Br4NOS: C, 32.52; H, 2.90; Br, 54.08; N, 2.37. Found: C, 32.20; H, 2.81; Br, 53.96; N, 2.23.

1-(1-Bromo-1-methylethyl)-4-formyl-1,2-dihydro[1,3]selenazolo[3,2-a]quinolin-10-ium tribromide (5d)

Yield 45%; mp 160–162°C; 1H NMR: δ 1.82 (s, 3H), 1.87 (s, 3H), 4.25 (m, 1H), 4.34 (d, J=9 Hz, 1H), 6.62 (d, J=9 Hz, 1H), 7.97 (t, J=7 Hz, 1H), 8.25 (t, J=7 Hz, 1H), 8.51 (d, J=8 Hz, 1H), 8.70 (d, J=8 Hz, 1H), 9.75 (s, 1H), 10.20 (s, 1H). Anal. Calcd for C15H15Br4NOSe: C, 28.88; H, 2.42; Br, 51.24; N, 2.25. Found: C, 28.29; H, 2.50; Br, 51.01; N, 2.13.

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Received: 2017-2-2
Accepted: 2017-4-21
Published Online: 2017-6-27
Published in Print: 2017-8-28

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