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Keywords:

  • aminohalogenation;
  • ketones;
  • N-alkyl-p-toluenesulfonamide;
  • nickel acetate;
  • α,β-unsaturated

Abstract

  1. Top of page
  2. Abstract
  3. Results and Discussion
  4. Experimental Section
  5. Acknowledgments
  6. References

The combinations of N-methyl-p-toluenesulfonamide/NBS and N-ethyl-p-toluenesulfonamide/NBS were found to be good nitrogen/halogen resources for the aminohalogenation of α,β-unsaturated ketones in the presence of Ni(OAc)2 as the catalyst for the synthesis of vicinal haloamino ketone derivatives. The introduction of N-alkyl groups to the nitrogen resources resulted in excellent regio- and stereoselectivity for both electron-donating and electron-withdrawing group-attached unsaturated ketone substrates. The structure of the resulting products has been unambiguously confirmed by X-ray crystal structure analysis.

The aminohalogenation and related reactions using functionalized olefins have been interesting topics in organic synthesis because the resulting vicinal haloamines are important building blocks in organic, bioorganic, and medicinal chemistry (1–14). The resulting vicinal haloamines from these reactions can readily undergo both intramolecular and intermolecular processes to afford aziridines (15–17), dehydroamino acids (18), and other important compounds (1–14). Although many synthetic approaches to vicinal haloamines have been developed using α,β-unsaturated carbonyls as substrates (19–27), the development of highly regio- and stereoselective aminohalogenation still remains challenging. So far, several nitrogen/halogen resources for the aminohalogenation reaction have been developed including N,N-dichloro-p-toluenesulfonamide (TsNCl2) (20–27), N,N-dibromo-p-toluenesulfonamide (TsNBr2) (28–31), chloramine-T (32–34), the combination of 2-NsNCl2/2-NsNHNa (2-Ns = 2-nitrobenzenesulfonyl) (35,36), and the combination of TsNH2 and NBS (37–39). In the above-known systems, there still exists shortcomings for α,β-unsaturated ketones in regard to substrate scope (40) and stereoselectivity (41–48).

In our continuous studies on aminohalogenation reaction, we designed a new nitrogen resource, in which alkyl groups are introduced to the nitrogen of p-toluenesulfonamide. We anticipate that the introduction of an alkyl group to nitrogen/halogen resource would change both steric and electronic environment of the key aziridinium intermediate formed during the reaction processes and could improve the regio- and stereoselectivity of aminohalogenation of α,β-unsaturated ketones, and chemical yields would also be improved in some difficult cases. In this work, we report the results of aminohalogenation of α,β-unsaturated ketones using N-alkyl-p-toluenesulfonamide as the nitrogen/halogen sources in the presence of Ni(OAc)2 as the catalyst as shown in Scheme 1.

image

Figure Scheme 1:.  Aminobromination of α,β-unsaturated ketones.

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Results and Discussion

  1. Top of page
  2. Abstract
  3. Results and Discussion
  4. Experimental Section
  5. Acknowledgments
  6. References

Initially, a readily available starting material chalcone (1a) was subjected to the reaction under normal catalytic conditions (37–39). The reaction was carried out in dichloromethane by using CuI as the catalyst in the presence of 4 Å molecular sieves. As expected, the corresponding aminobrominated product (2a) was found (46% yield). To improve the yield, a variety of metal catalysts, such as Ni(OAc)2, NiCl2, Cu(OAc)2, CuCl2, CuI, and CuCl, were then applied. As shown in Table 1, among all employed catalysts, Ni(OAc)2 was found to be the best one, which made the reaction to occur smoothly within 24 h in a chemical yield of 82% (entry 1, Table 1). Another nickel salt, NiCl2, was also found to be a good catalyst for this reaction, but gave a lower yield of 42% (entry 2, Table 1). Metal copper can serve as the catalyst for this reaction and showed good catalytic activity (entries 3–6, Table 1), especially, for Cu(OAc)2, 80% yield was obtained (entry 3, Table 1), which is similar to that of Ni(OAc)2-catalyzed case. A slightly lower yield was obtained when the catalyst loading was reduced to 5% (entry 7, Table 1).

Table 1.   Aminobromination of chalcone 1aaThumbnail image of

To further improve the catalytic system, several other common organic solvents were examined (Table 2). Dichloromethane was found to be the most suitable solvent for this reaction (entry 1, Table 2). Other solvents, such as acetonitrile, ethyl acetate, and chloroform gave lower yields (entries 2, 3 and 6, Table 2). Nearly no bromoamine products were observed when reaction was conducted in THF or DMF (entries 4 and 5, Table 2). 4 Å molecular sieves were found to be necessary for the reaction, and the yield was decreased to 59% without the addition of 4 Å molecular sieves (entry 8, Table 2). It was turned out that temperature played an important role in present catalyst reaction, only 15% yield was obtained when the reaction was carried out at room temperature (entry 7, Table 2) with much of the starting materials remained. At 45 °C, the reaction can be finished within 24 h. No further improvement was observed when the reaction period was prolonged (entry 10, Table 2). Shortening the reaction time to 12 h resulted in a much lower yield of 2a (51%, entry 9, Table 2). It was found that at least 1.5 equiv. of TsNHCH3 and 2 equiv. of NBS were needed for complete conversion of chalcone (1a). Otherwise, the yield was decreased from 82% to 68% when 1.2 equiv. of TsNHCH3 and 1.5 equiv. of NBS were used (entry 12, Table 2).

Table 2.   Aminobromination of 2a under various conditionsaThumbnail image of

After the reaction condition was optimized, we examined the scope and limitation of α,β-unsaturated ketone substrates. As shown in Table 3, a variety of α,β-unsaturated ketones were found to be suitable for this reaction. The corresponding vicinal haloamines were formed in modest to good yields, no matter what substituents on the aromatic rings of these α,β-unsaturated ketones. It should be noted that in a previous known system nearly no haloamines were formed when strong electron-withdrawing group-attached α,β-unsaturated ketones were employed as the substrates (40). In contrast, the ketone substrate with 4-F substituent on aromatic ring afforded 66% yield in present system (entry 2, Table 3), which would be attributed to the fact that the existence of the electron-donating methyl group on the nitrogen of p-toluenesulfonamide can make aziridinium intermediates more stable, which makes the reaction easier to occur. For each of these cases, the regioselectivity was completely controlled without observing any regioisomer. In addition, when compared with previous aminohalogenation of unsaturated ketones (41,42), introducing a methyl group to p-toluenesulfonamide resulted in excellent stereoselectivity. The product structure has been unambiguously confirmed by X-ray structural analysis of the single crystal analysis of 2a (Figure 1).

Table 3.   Aminobromination of α,β-unsaturated ketonesaThumbnail image of
image

Figure 1.  X-ray crystal structure of compound 2a.

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To further investigate the alkyl effect on this catalytic system, TsNHC2H5, which contains a larger alkyl group on the nitrogen atom, was used as the nitrogen source for this reaction under the same conditions. As shown in Table 4, for all α,β-unsaturated ketone substrates, the corresponding haloamines were smoothly generated, albeit yields are not as high as those of TsNHCH3-based aminohalogenation system, but both regio- and stereoselectivity have been controlled very well.

Table 4.   Aminobromination of α,β-unsaturated ketonesaThumbnail image of

As noted before, this reaction was suggested to proceed through a similar mechanism involving the formation of N-alkyl-p-tosylaziridinium intermediate at its initial step (41,43). The NBS reacts with TsNHCH3 to give Ts-NBrCH3 first. The metal catalyst can facilitate cleavage of the resulting TsNBrCH3 species to give ‘Ts-N+-CH3’ species for the subsequent electrophilic addition for the formation of N-alkyl-p-tosylaziridinium intermediate. The alkyl groups on nitrogen atom can help controlling the stereochemistry by blocking possible syn attacking N-alkyl-p-tosylaziridinium intermediate by Br species. As shown in previous systems, the regioselectivity is well explained by the fact that the β-position of the aziridinium intermediate is loaded by more positive charge than that of its α-position because of the stabilization effect from aryl groups.

In conclusion, a series of vicinal haloamino ketones have been successfully synthesized via aminohalogenation of α,β-unsaturated ketones using two new combinations of N-methyl-toluenesulfonamide/NBS and N-ethyl-toluenesulfonamide/NBS as nitrogen/halogen resources and using Ni(OAc)2 as the catalyst. Alkyl groups on nitrogen/halogen sources were found to benefit regio- and stereochemistry control for this reaction. The new catalytic system was proven to be efficient for difficult substrates that are attached with strong electron-withdrawing group on their aromatic rings.

Experimental Section

  1. Top of page
  2. Abstract
  3. Results and Discussion
  4. Experimental Section
  5. Acknowledgments
  6. References

General Remarks

All reactions were conducted under nitrogen atmosphere. Solvents were dried and distilled prior to use. IR spectra were collected with Bruker Vector 22 instrument (KBr pellets). Thin-layer chromatography was performed on silica gel 60 (F-254) TLC plates (20 cm × 20 cm). 1H NMR (300 MHz) and 13C NMR (75 MHz) were collected in CDCl3 with a Bruker ARX 300 spectrometer. Elemental analyses were performed with a Perkin–Elmer 240 elemental analysis instrument. Mass spectra of new compounds were measured with a Finnigan LCQ Electrospray Mass Spectrometer.

Typical experimental procedure

Into a dry vial was added α,β-unsaturated ketones (1 mmol), N-alkyl-p-toluenesulfonamide (1.5 mmol, 1.5 equiv), Ni(OAc)2 (14 mg, 0.08 mmol, 0.08 equiv), 4 Å MS (500 mg, predried in an oven at 200 °C overnight in vacuum), then freshly distilled CH2Cl2 (3.0 mL) under a nitrogen atmosphere. The mixture was stirred at room temperature for 10 min before NBS (360 mg, 2.0 mmol, 2.0 equiv) dissolving in CH2Cl2 (5 mL) was added. The resulting green mixture was stirred at 45 °C for 24 h in the capped vial. The reaction was quenched by dropwise addition of saturated aqueous Na2SO3 solution (3 mL). The organic phases were separated and the aqueous phase was extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with water and brine, dried with anhydrous Na2SO4, concentrated to dryness, and purified by TLC plate (EtOAc/petroleum ether, 1:4 v/v) to give the product.

3-Bromo-1,3-diphenyl-2-(N-methyltosylamino)propan-1-one (2a): White solid (387 mg, 82% yield). Mp 156–158 °C; IR (KBr): 3065, 2924, 1676, 1595, 1450, 1314, 1223, 1159, 1086, 923, 754, 681, 552 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.21 (d, = 7.1 Hz, 2H), 7.71-7.66 (m, 1H), 7.64-7.61 (m, 2H), 7.56 (t, = 7.6 Hz, 2H), 7.47-7.43 (m, 3H), 6.95-6.88 (m, 4H), 6.56 (d, = 11.1 Hz, 1H), 5.46 (d, = 11.1 Hz, 1H), 2.53 (s, 3H), 2.27 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.3, 143.3, 137.3, 135.9, 135.0, 134.1, 129.3, 129.3, 129.2, 129.0, 128.9, 128.8, 127.3, 59.4, 48.8, 29.2, 21.3; ESMS: calcd [M + Na]: 494.04; found 494.00. Anal. calcd for C23H22BrNO3S: C, 58.48%; H, 4.69%; N, 2.97%. Found C, 58.34%; H, 4.69%; N, 2.99%.

3-Bromo-3-(4-fluorophenyl)-1-phenyl-2-(N-methyltosylamino)propan-1-one (2b): White solid (318 mg, 65% yield). Mp 147–148 °C; IR (KBr): 3071, 1677, 1596, 1447, 1310, 1229, 1156, 1086, 919, 845, 763, 680, 557 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.17 (dd, = 1.3, 7.2 Hz, 2H), 7.71-7.66 (m, 1H), 7.62-7.58 (m, 2H), 7.57-7.53 (m, 2H), 7.14-7.08 (m, 2H), 7.01 (dd, = 1.8, 6.5 Hz, 2H), 6.92 (d, = 8.1 Hz, 2H), 6.49 (d, = 11.1 Hz, 1H), 6.45 (d, = 11.1 Hz, 1H), 2.55 (s, 3H), 2.28 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.1, 164.7, 161.4, 143.4, 136.0, 135.1, 134.1, 133.2, 133.1, 130.7, 130.5, 129.2, 129.2, 128.8, 127.1, 116.1, 115.8, 59.6, 47.9, 29.1, 21.3; ESMS: calcd [M+Na]: 512.03; found 512.00. Anal. calcd for C23H21BrFNO3S: C, 56.33%; H, 4.32%; N, 2.86%. Found C, 56.27%; H, 4.22%; N 2.87%.

3-Bromo-3-(4-chlorophenyl)-1-phenyl-2-(N-methyltosylmino)propan-1-one (2c): White solid (430 mg, 85% yield). Mp 158–159 °C; IR (KBr): 2963, 2862, 1683, 1595, 1449, 1327, 1222, 1157, 1088, 935, 765, 680, 550 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.18 (dd, = 1.5, 7.2 Hz, 2H), 7.71-7.66 (m, 1H), 7.59-7.51 (m, 4H), 7.38 (dd, = 1.9, 7.6 Hz, 2H), 7.01-6.92 (m, 4H), 6.47 (d, = 11.0 Hz, 1H), 5.41 (d, J = 11.0 Hz, 1H), 2.56 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.1, 143.5, 135.9, 135.8, 135.2, 135.0, 134.1, 130.0, 129.3, 129.2, 129.1, 128.8, 127.1, 59.6, 47.7, 29.2, 21.3; ESMS: calcd [M + Na]: 528.00; found 528.00. Anal. calcd for C23H21BrClNO3S: C, 54.50%; H, 4.18%; N, 2.76%. Found: C, 54.46%; H, 4.11%; N, 2.78%.

3-Bromo-3-(4-bromophenyl)-1-phenyl-2-(N-methyltosylamino)propan-1-one (2d): White solid (369 mg, 67% yield). Mp 161–163 °C; IR (KBr): 3059, 2923, 1679, 1594, 1449, 1327, 1222, 1156, 1088, 935, 764, 679, 551 cm−1; 1H NMR(300 MHz, CDCl3): δ 8.18 (dd, J = 1.4, 7.1 Hz, 2H), 7.68 (t, J = 7.4 Hz, 1H), 7.58-7.52 (m, 4H), 7.48-7.44 (m, 2H), 7.00-6.93 (m, 4H), 6.46 (d, J = 11.0 Hz, 1H), 5.39 (d, J = 11.0 Hz, 1H), 2.56 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.0, 143.5, 136.4, 135.8, 135.0, 134.1, 132.1, 130.3, 129.3, 129.2, 128.9, 127.1, 123.4, 59.5, 47.7, 29.2, 21.4; ESMS: calcd [M + Na]: 571.95; found 571.92. Anal. calcd for C23H21Br2NO3S: C, 50.11%; H, 3.84%; N, 2.54%. Found: C, 50.04%; H, 3.86%; N, 2.51%.

3-Bromo-3-(2-chlorophenyl)-1-phenyl-2-(N-methyltosylamino)propan-1-one (2e): White solid (365 mg, 72% yield). Mp 137–138 °C; IR (KBr): 3068, 1685, 1595, 1447, 1325, 1220, 1155, 1086, 933, 755, 681, 560 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.17 (d, J = 7.4 Hz, 2H), 7.98 (d, J = 7.8 Hz, 1H), 7.69 (t, J = 7.4 Hz, 1H), 7.56 (t, J = 7.8 Hz, 2H), 7.49-7.40 (m, 2H), 7.37-7.31 (m, 1H), 7.01 (d, = 8.3 Hz, 2H), 6.90 (d, = 8.3 Hz, 2H), 6.60 (d, = 11.0 Hz, 1H), 6.07 (d, = 11.0 Hz, 1H), 2.57 (s, 3H), 2.27 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.0, 143.4, 136.1, 135.0, 134.8, 134.1, 133.5, 131.0, 130.2, 129.9, 129.2, 129.2, 128.9, 127.8, 127.2, 59.8, 43.7, 29.6, 21.3; ESMS: calcd [M+Na]: 528.00; found 528.08. Anal. calcd for C23H21BrClNO3S: C, 54.50%; H, 4.18%; 2.76%. Found: C, 50.60%; H, 4.11%; N, 2.78%.

3-Bromo-1-(4-chlorophenyl)-3-phenyl-2-(N-methyltosylamino)propan-1-one (2f): White solid (345 mg, 68% yield). Mp 159–161 °C; IR (KBr): 3098, 3005, 1681, 1590, 1402, 1314, 1223, 1159, 1089, 924, 809, 766, 695, 554 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.15 (dd, = 1.9, 6.8 Hz, 2H), 7.61-7.58 (m, 2H), 7.53 (dd, = 1.9, 6.8 Hz, 2H), 7.44-7.42 (m, 3H), 6.94 (s, 4H), 6.46 (d, = 11.0 Hz, 1H), 5.42 (d, = 11.0 Hz, 1H), 2.53 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 193.3, 143.5, 140.7, 137.2, 135.0, 134.2, 130.7, 129.3, 129.2, 129.2, 129.0, 128.7, 127.3, 59.4, 48.7, 29.2, 21.3; ESMS: calcd [M + Na]: 528.00; found 527.92. Anal. calcd for C23H21BrClNO3S: C, 54.50%; H, 4.18%; 2.76%. Found: C, 54.42%; H, 4.18%; N, 2.78%.

3-Bromo-1-(4-bromophenyl)-3-phenyl-2-(N-methyltosylamino)propan-1-one (2g): White solid (303 mg, 55% yield). Mp 166–168 °C; IR (KBr): 3095, 3059, 1677, 1581, 1458, 1343, 1220, 1161, 1069, 932, 809, 763, 673, 551 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.06 (dd, = 2.0, 6.7 Hz, 2H), 7.70 (dd, = 2.0, 6.7 Hz, 2H), 7.61-7.58 (m, 2H), 7.44-7.42 (m, 3H), 6.94 (s, 4H), 6.45 (d, = 11.0 Hz, 1H), 5.41 (d, = 11.0 Hz, 1H), 2.53 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 193.5, 143.5, 137.2, 135.0, 134.7, 132.2, 130.7, 129.5, 129.3, 129.2, 129.0, 128.7, 127.3, 59.4, 48.7, 29.2, 21.3; ESMS: calcd [M + Na]: 571.95; found 571.92. Anal. calcd for C23H21Br2NO3S: C, 58.11%; H, 3.84%; N, 2.54%. Found: C, 50.10%; H, 3.76%; N, 2.55%.

3-Bromo-3-(4-methylphenyl)-1-phenyl-2-(N-methyltosylamino)propan-1-one (2h): White solid (243 mg, 50% yield). Mp 160–162 °C; IR (KBr): 3068, 2921, 1673, 1594, 1448, 1316, 1228, 1158, 1086, 924, 828, 761, 652, 557 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.19 (dd, J = 1.5, 7.2 Hz, 2H), 7.71-7.66 (m, 1H), 7.58-7.49 (m, 4H), 7.24 (d, J = 8.0 Hz, 2H), 6.97 (dd, J = 1.9, 6.4 Hz, 2H), 6.88 (d, J = 8.1 Hz, 2H), 6.53 (d, J = 11.0 Hz, 1H), 5.44 (d, J = 11.0 Hz, 1H), 2.54 (s, 3H), 2.42 (s, 3H), 2.28 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.4, 143.2, 139.3, 136.1, 135.2, 134.3, 134.0, 129.6, 129.3, 129.1, 128.8, 128.6, 127.3, 59.3, 49.0, 29.2, 21.3; ESMS: calcd [M + Na]: 508.06; found 507.92. Anal. calcd for C24H24BrNO3S: C, 59.26%; H, 4.97%; N, 2.88%. Found: C, 59.21%; H, 4.99%; N, 2.81%.

3-Bromo-1-(4-methylphenyl)-3-phenyl-2-(N-methyltosylamino)propan-1-one (2i): White solid (203 mg, 42% yield). Mp 167–169 °C; IR (KBr): 3066, 2921, 1672, 1601, 1457, 1341, 1224, 1160, 1085, 930, 806, 754, 671, 553 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.12 (d, J = 8.2 Hz, 2H), 7.63-7.60 (m, 2H), 7.44-7.42 (m, 3H), 7.36 (d, J = 8.2 Hz, 2H), 6.96-6.88 (m, 4H), 6.52 (d, J = 11.1 Hz, 1H), 5.44 (d, J = 11.1 Hz, 1H), 2.52 (s, 3H), 2.48 (s, 3H), 2.27 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 193.9, 145.2, 143.3, 137.5, 135.0, 133.4, 129.6, 129.5, 129.2, 129.2, 129.0, 128.8, 127.4, 59.2, 48.8, 29.2, 21.8, 21.3; ESMS: calcd [M + Na]: 508.06; Found 508.00. Anal. calcd for C24H24BrNO3S: C, 59.26%; H, 4.97%; N, 2.88%. Found: C, 59.21%; H, 4.99%; N, 2.86%.

3-Bromo-3-(4-chlorophenyl)-1-(4-methylphenyl)-2-(N-methyltosylamino)propan-1-one (2j): White solid (224 mg, 43% yield). Mp 164–166 °C; IR (KBr): 3068, 2998, 1669, 1604, 1493, 1337, 1215, 1159, 1086, 930, 806, 766, 671, 560 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.10 (d, J = 8.2 Hz, 2H), 7.52 (dd, = 1.8, 6.7 Hz, 2H), 7.39-7.34 (m, 4H), 7.02-6.93 (m, 4H), 6.44 (d, = 11.1 Hz, 1H), 5.40 (d, = 11.1 Hz, 1H), 2.55 (s, 3H), 2.48 (s, 3H), 2.30 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 193.6, 145.3, 143.5, 136.0, 135.1, 135.0, 133.3, 130.0, 129.6, 129.4, 129.2, 129.1, 127.2, 59.4, 47.8, 29.2, 21.8, 21.3; ESMS: calcd [M + Na]: 542.02; found: 541.92. Anal. calcd for C24H23BrClNO3S: C, 55.34%; H, 4.45%; N, 2.69%. Found: C, 55.27%; H, 4.45%; N, 2.59%.

3-Bromo-1-(4-methylphenyl)-3-(4-methylphenyl)-2-(N-methyltosylamino)propan-1-one (2k): White solid (350 mg, 70% yield). Mp 152–153 °C; IR (KBr): 3071, 2921, 1674, 1602, 1334, 1228, 1158, 1087, 934, 792, 676, 541 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.11 (d, J = 8.2 Hz, 2H), 7.50 (d, J = 8.2 Hz, 2H), 7.36 (d, = 8.0 Hz, 2H), 7.23 (d, = 8.0 Hz, 2H), 6.99-6.96 (dd, = 1.8, 6.5 Hz, 2H), 6.89 (d, J = 8.1 Hz, 2H), 6.50 (d, = 11.1 Hz, 1H), 5.43 (d, = 11.1 Hz, 1H), 2.53 (s, 3H), 2.48 (s, 3H), 2.41 (s, 3H), 2.28 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 194.0, 145.1, 143.2, 139.2, 135.2, 134.4, 133.5, 129.6, 129.5, 129.5, 129.1, 128.6, 127.3, 59.2, 49.1, 29.2, 21.8, 21.3, 21.3; ESMS: calcd [M + Na]: 522.07; found: 522.00. Anal. calcd for C25H26BrNO3S: C, 60.00%; H, 5.24%; N, 2.80%. Found: C, 59.73%; H, 50.14%; N, 2.83%.

3-Bromo-1,3-diphenyl-2-(N-ethyltosylamino)propan-1-one (3a): White solid (185 mg, 38% yield). Mp 163–165 °C; IR (KBr): 3064, 2979, 1677, 1595, 1449, 1324, 1219, 1154, 1086, 927, 746, 679, 554 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.22 (d, = 7.0 Hz, 2H), 7.72-7.67 (m, 1H), 7.66-7.62 (m, 2H), 7.61-7.55 (m, 2H), 7.45-7.42 (m, 3H), 6.95-6.91 (m, 4H), 6.64 (d, = 11.1 Hz, 1H), 5.57 (d, = 11.1 Hz, 1H), 3.15-3.08 (m, 2H), 2.28 (s, 3H), 0.71 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.5, 143.4, 137.4, 136.2, 136.1, 134.0, 129.3, 129.3, 129.2, 129.1, 128.9, 128.8, 127.5, 59.8, 49.8, 39.0, 21.3, 14.3; ESMS: calcd [M + Na]: 508.06; found: 507.92. Anal. calcd for C24H24BrNO3S: C, 59.26%; H, 4.97%; N, 2.88%. Found: C, 59.21%; H, 4.99%; N, 2.78%.

3-Bromo-3-(4-fluorophenyl)-1-phenyl-2-(N-ethyltosylamino)propan-1-one (3b): White solid (333 mg, 66% yield). Mp 166–168 °C; IR (KBr): 3072, 2977, 1677, 1595, 1448, 1326, 1231, 1153, 1087, 926, 844, 758, 678, 561 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.19 (d, = 7.4 Hz, 2H), 7.70 (t, J = 7.4 Hz, 1H), 7.64-7.55 (m, 4H), 7.11 (t, J = 8.6 Hz, 2H), 7.01 (d, = 8.4 Hz, 2H), 6.92 (d, = 8.4 Hz, 2H), 6.56 (d, = 10.9 Hz, 1H), 5.56 (d, = 10.9 Hz, 1H), 3.17-3.09 (m, 2H), 2.29 (s, 3H), 0.73 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.4, 164.6, 161.3, 143.5, 136.3, 136.1, 134.0, 133.3, 133.2, 131.2, 131.1, 129.2, 129.2, 128.9, 127.4, 115.9, 115.6, 60.1, 48.9, 39.0, 21.3, 14.4; ESMS: calcd [M + Na]: 526.05; found 526.00. Anal. calcd for C24H23BrFNO3S: C, 57.15%; H, 4.60%; N, 2.78%. Found: C, 57.16%; H, 4.64%; N, 2.71%.

3-Bromo-3-(4-chlorophenyl)-1-phenyl-2-(N-ethyltosylamino)propan-1-one (3c): White solid (338 mg, 65% yield). Mp 147–148 °C; IR (KBr): 3068, 2976, 1678, 1594, 1447, 1328, 1221, 1155, 1088, 924, 750, 677, 554 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.20 (d, = 7.4 Hz, 2H), 7.69 (t, = 7.4 Hz, 1H), 7.60-7.54 (m, 4H), 7.38 (d, = 8.5 Hz, 2H), 7.00-6.92 (m, 4H), 6.54 (d, = 11.1Hz, 1H), 5.53 (d, = 11.1, 1H), 3.13 (q, J = 7.2 Hz, 2H,), 2.30 (s, 3H), 0.76 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.3, 143.5, 136.1, 135.9, 135.1, 134.1, 130.6, 129.3, 129.2, 129.0, 128.9, 127.4, 60.0, 48.6, 39.1, 21.3, 14.5; ESMS: calcd [M + Na]: 542.02; found 542.00. Anal. calcd for C24H23BrClNO3S: C, 55.34%; H, 4.45%; N, 2.69%. Found: C, 55.35%; H, 4.41%; N, 2.69%.

3-Bromo-3-(4-bromophenyl)-1-phenyl-2-(N-ethyltosylamino)propan-1-one (3d): White solid (333 mg, 59% yield). Mp 156–157 °C; IR (KBr): 3062, 2975, 1677, 1593, 1447, 1329, 1221, 1155, 1074, 924, 750, 678, 552 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.20 (d, = 7.4 Hz, 2H), 7.69 (t, = 7.4 Hz, 1H), 7.60-7.47 (m, 6H), 7.00-6.93 (m, 4H), 6.54 (d, = 10.8 Hz, 1H), 5.51 (d, = 10.8 Hz, 1H), 3.13 (q, = 7.2 Hz, 2H), 2.31 (s, 3H), 0.77 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.3, 143.5, 136.5, 136.0, 135.9, 134.1, 132.0, 130.9, 129.3, 129.2, 128.9, 127.4, 123.3, 59.9, 48.7, 39.1, 21.4, 14.5; ESMS: calcd [M + Na]: 585.97; found 585.92. Anal. calcd for C24H23Br2NO3S: C, 50.99%; H, 4.10%; N, 2.48%. Found: C, 50.99%; H, 4.21%; N, 2.48%.

3-Bromo-1-(4-chlorophenyl)-3-phenyl-2-(N-ethyltosylamino)propan-1-one (3e): White solid (245 mg, 47% yield). Mp 159–161 °C; IR (KBr): 3093, 2973, 1677, 1591, 1322, 1220, 1154, 1090, 923, 758, 673, 555 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.20-8.15 (m, 2H), 7.62-7.58 (m, 2H), 7.57-7.52 (m, 2H), 7.45-7.41 (m, 3H), 6.94 (s, 4H), 6.55 (d, = 11.1 Hz, 1H), 5.53 (d, = 11.1 Hz, 1H), 3.19-3.03 (m, 2H), 2.30 (s, 3H), 0.74 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 194.5, 143.6, 140.7, 137.3, 135.9, 134.2, 130.7, 129.3, 129.2, 129.2, 128.9, 127.6, 59.8, 49.6, 39.1, 21.3, 14.4; ESMS: calcd [M + Na]: 542.02; found 541.92. Anal. calcd for C24H23BrClNO3S: C, 55.34%; H, 4.45%; N, 2.69%. Found: C, 55.34%; H, 4.99%; N, 2.69%.

3-Bromo-1-(4-bromophenyl)-3-phenyl-2-(N-ethyltosylamino)propan-1-one (3f): White solid (254 mg, 45% yield). Mp 147–148 °C; IR (KBr): 3061, 2978, 1676, 1584, 1322, 1219, 1154, 1072, 923, 756, 671, 554 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.09 (d, = 8.4 Hz, 2H), 7.71 (d, = 8.4 Hz, 2H), 7.61-7.59 (m, 2H), 7.44-7.42 (m, 3H), 6.94 (s, 4H), 6.54 (d, = 11.1 Hz, 1H), 5.53 (d, = 11.1 Hz, 1H), 3.19-3.03 (m, 2H), 2.30 (s, 3H), 0.74 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 194.7, 143.6, 137.3, 135.9, 134.7, 132.2, 130.7, 129.5, 129.3, 129.2, 129.2, 128.9, 127.6, 59.8, 49.7, 39.1, 21.4, 14.4; ESMS: calcd [M + Na]: 585.97; found 586.00. Anal. calcd for C24H23Br2NO3S: C, 50.99%; H, 4.10%; N, 2.48%. Found: C, 59.97%; H, 4.09%; N, 2.47%.

3-Bromo-3-(4-methylphenyl)-1-phenyl-2-(N-ethyltosylamino)-1-one (3g): White solid (200 mg, 40% yield). Mp 169–170 °C; IR (KBr): 3064, 2976, 1675, 1595, 1448, 1326, 1224, 1154, 1087, 926, 819, 753, 678, 538 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.21 (dd, = 1.4, 7.1 Hz, 2H), 7.71-7.66 (m, 1H), 7.60-7.50 (m, 4H), 7.24 (d, = 7.9 Hz, 2H), 6.95 (dd, = 2.0, 6.5 Hz, 2H), 6.89 (d, = 8.5 Hz, 2H), 6.61 (d, = 11.1 Hz, 1H), 5.55 (d, = 11.1 Hz, 1H), 3.12 (q, = 7.2 Hz, 2H), 2.42 (s, 3H), 2.28 (s, 3H), 0.74 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.7, 143.2, 139.2, 136.3, 136.2, 134.4, 133.9, 129.5, 129.3, 129.2, 129.1, 128.8, 127.5, 59.8, 50.0, 39.1, 21.3, 14.4; ESMS: calcd [M + Na]: 522.07; found 522.00. Anal. calcd for C25H26BrNO3S: C, 60.00%; H, 5.24%; N, 2.80%. Found: C, 60.00%; H, 5.27%; N, 2.80%.

3-Bromo-1-(4-methylphenyl)-3-phenyl-2-(N-ethyltosylamino)-1-one (3h): White solid (160 mg, 32% yield). Mp 175–177 °C; IR (KBr): 3065, 2976, 1670, 1604, 1450, 1322, 1265, 1158, 1084, 929, 750, 674, 550 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.14 (d, = 8.1 Hz, 2H), 7.65-7.62 (m, 2H), 7.46-7.42 (m, 3H), 7.38 (d, J = 8.1 Hz, 2H), 6.95-6.89 (m, 4H), 6.61 (d, = 10.8 Hz, 1H), 5.56 (d, = 10.8 Hz, 1H), 3.15-3.06 (m, 2H), 2.48 (s, 3H), 2.28 (s, 3H), 0.72 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.0, 145.2, 143.3, 137.5, 136.2, 133.5, 129.6, 129.4, 129.3, 129.1, 129.1, 128.8, 127.6, 59.6, 49.8, 39.1, 21.8, 21.3, 14.3; ESMS: calcd [M + Na]: 522.07; found 522.04. Anal. calcd for C25H26BrNO3S: C, 60.00%; H, 5.24%; N, 2.80%. Found: C, 59.98%; H, 5.23%; N, 2.81%.

3-Bromo-3-(4-chlorophenyl)-1-(4-methylphenyl)-2-(N-ethyltosylamino)-1-one (3i): White solid (160 mg, 30% yield). Mp 153–155 °C; IR (KBr): 3068, 2973, 1674, 1602, 1493, 1303, 1155, 1089, 925, 833, 757, 684, 553 cm−1; 1H NMR (300 MHz, CDCl3): δ 8.11 (d, J = 8.3 Hz, 2H), 7.54 (d, = 8.6 Hz, 2H), 7.37 (d, = 8.6 Hz, 4H), 6.97 (m, 4H), 6.52 (d, = 11.1Hz, 1H), 5.52 (d, = 11.1 Hz, 1H), 3.12 (q, = 7.2 Hz, 2H), 2.48 (s, 3H), 2.31 (s, 3H), 0.76 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 194.7, 145.3, 143.5, 136.1, 135.0, 133.4, 130.6, 129.6, 129.4, 129.2, 128.9, 127.4, 59.8, 49.7, 39.1, 21.8, 21.3, 14.5; ESMS: calcd [M + Na]: 556.03; found 556.00. Anal. calcd for C25H25BrClNO3S: C, 56.14%; H, 4.71%; N, 2.62%. Found: C, 56.10%; H, 4.73%; N, 2.61%.

3-Bromo-1-(4-methylphenyl)-3-(4-methylphenyl)-2-(N-ethyltosylamino)-1-one (3j): White solid (216 mg, 42% yield). Mp 154–156 °C; IR (KBr): 3095, 2922, 1672, 1603, 1442, 1323, 1155, 1086, 928, 819, 767, 675, 552 cm−1; 1H NMR (300 MHz, CDCl3) : δ 8.13 (d, = 8.5 Hz, 2H), 7.51 (d, = 8.5 Hz, 2H), 7.37 (d, = 8.3 Hz, 2H), 7.23 (d, = 8.3 Hz, 2H), 6.96 (dd, = 1.1, 7.0 Hz, 2H), 6.89 (d, = 8.1 Hz, 2H), 6.58 (d, = 11.0 Hz, 1H), 5.54 (d, = 11.0 Hz, 1H), 3.11 (q, = 7.2 Hz, 2H), 2.48 (s, 3H), 2.42 (s, 3H), 2.29 (s, 3H), 0.74 (t, = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 195.1, 145.1, 143.2, 139.1, 136.3, 134.5, 133.6, 129.6, 129.4, 129.2, 129.0, 127.6, 59.6, 50.1, 39.1, 21.8, 21.3, 21.3, 14.4; ESMS: calcd [M + Na]: 536.09; found 536.08. Anal. calcd for C26H28BrNO3S: C, 60.70%; H, 5.49%; N, 2.72%. Found: C, 60.70%; H, 50.50%; N, 2.69%.

Crystal Data of 2a: C23H22BrNO3S; formula weight, 472.39; monoclinic, space group P-1; a = 9.3355(17), b = 9.7351(18), c = 13.257(3) Å; α = 71.587(2)°, β = 80.260(2)°, γ = 71.765(3)°; V = 1082.4(4) Å3; Z = 2; Dcalcd = 1.449 g/cm3; F(000) = 484; crystal size = 0.24 mm × 0.26 mm × 0.30 mm; 2θmax = 52.0°; reflections collected, 5881; unique: 4157 (Rint = 0.1032); parameter: 264; R1 = 0.0534; wR2 = 0.1401; GOF = 1.005. CCDC-723901 (for 2a) contains the supplementary crystallographic data for this study. These data can be obtained free of charge from The Cambridge crystallographic Data Centre via http://www.ccdc.cam.ac.uk/data_request/cif.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Results and Discussion
  4. Experimental Section
  5. Acknowledgments
  6. References

We gratefully acknowledge financial support from the National Natural Science Foundation of China (No. 20772056, to Y.P.) and the Welch Foundation (D-1361, to G.L., USA). This work was also partially supported by research funds to Y.P. from the Qing-Lan Program of Jiangsu Province and the Kua-Shi-Ji Program of the Education Ministry of China.

References

  1. Top of page
  2. Abstract
  3. Results and Discussion
  4. Experimental Section
  5. Acknowledgments
  6. References
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