CC BY ND NC 4.0 · SynOpen 2017; 01(01): 0001-0007
DOI: 10.1055/s-0036-1590200
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Iodobenzene-Promoted Pd-Catalysed ortho-Directed C–H Activation: The Synthesis of Benzothiazoles via Intramolecular Coupling

Meng-Tian Zenga, Wan Xua, Min Liua, Xing Liua, Cai-Zhu Changa, Hui Zhua, Zhi-Bing Dong*a, b
  • aSchool of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430074, P. R. of China
  • bKey Laboratory of Green Chemical Process, Ministry of Education, Wuhan Institute of Technology, Wuhan 430074, P. R. of China   Email: dzb04982@wit.edu.cn
Supported by: We acknowledge financial support from: National Natural Science Foundation of China (21302150)
Supported by: Hubei Provincial Department of Education (D20131501)
Supported by: Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry [2012]1707
Supported by: President Foundation of Wuhan Institute of Technology (2014038)
Supported by: Foundation of ChutianDdistinguished Fellow from Hubei Provincial Department of Education, Foundation of High-end Talent Cultivation Program from Wuhan Institute of Technology.
Further Information

Publication History

Received: 08 February 2017

Accepted after revision: 01 March 2017

Publication Date:
16 March 2017 (online)

 

Abstract

A series of 2-aminobenzothiazoles were synthesized by a palladium-catalysed oxidative coupling with good yields (62–89%). Iodobenzene was found to be effective as an additive in this intramolecular C–S bond-formation reaction. The directing thiourea group attached to the aryl ring is essential for the activation of the ortho C–H bond.


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Benzothiazole derivatives represent an extensive group of heterocyclic compounds, several of which have already found application in the medical sphere as antitumor agents[1] with selective growth inhibitory properties against human cancer cell lines and in agriculture as plant growth regulators (PGR).[2] 2-Aminobenzothiazoles can be obtained through either intermolecular transformations, which are dominated by condensation reactions,[3] [4] [5] [6] [7] or intramolecular transformations, which include cross-coupling reactions[8–10] starting from ortho-haloaryl thioureas, and oxidative coupling reactions.[11] [12] [13] [14] [15] Herein, we present an iodobenzene-promoted Pd-catalysed synthesis of benzothiazoles via intramolecular coupling.

The initial study involved palladium-catalysed ortho-directed C–H activation for cross-coupling with iodobenzene. The model reaction we chose was the intermolecular oxidative coupling reaction between 1,1-dimethyl-3-phenyl­thiourea and iodobenzene. Gratifyingly, the intermolecular cross-coupling product was not detected, and the intramolecular cyclisation product (2-aminobenzothiazole) was furnished with a satisfactory yield of 81% (Scheme [1]). The oxidative coupling product could not be obtained when no iodobenzene was present. Much less (23%) intramolecular cyclisation product was formed when the reaction was performed under nitrogen, revealing that atmospheric oxygen was the oxidant, and that iodobenzene was a necessary additive.

Zoom Image
Scheme 1 Control experiments for the PhI-promoted synthesis of benzothiazole

Encouraged by these results, we began to optimise the reaction conditions. First, a broad screening of copper and palladium catalysts revealed that copper salts were ineffective (Table1, entries 1–3), but palladium catalysts, for example, PdBr2, PdCl2, Pd(OAc)2 could catalyse the model reaction to give the cyclisation products with 64%, 69% and 81% isolated yields, respectively (Table1, entries 5, 4 and 8). Various other additives, for example, pyridine, ethyldiisopropylamine, KF, CsF and LiCl (Table [1], entries 18–22) that might promote the model reaction were screened, but results showed that these additives were less active than iodobenzene in promoting the intramolecular cyclisation. The additive loading was also investigated, with the optimal additive loading being found to be 0.5 equiv, with 1.0 or 1.5 equiv not improving the yield significantly, and a lower loading (0.1 equiv relative to thiourea) resulted in the yield reducing to 65%.

Substituted iodobenzenes proved to be less reactive than iodobenzene (Table [1], entries 8, 16 and 17). A range of bases, such as NaH, CH3ONa, NaOH, KOt-Bu, Cs2CO3, K2CO3, Na2CO3 and NEt3 was surveyed and K2CO3 was found to be the most suitable base for this reaction (Table [1], entries 8–15). Solvent and temperature studies showed that DMSO was the best solvent (Table [1], entries 8, 23–25) and 100 °C was the optimal temperature (Table1, entries 8, 26–28). Under­ the optimal reaction conditions, various substituted N-arylthioureas (1ap) underwent cyclisation smoothly, providing the corresponding 2-aminobenzothiazoles (2ap) in good yields. Substrate scope experiments revealed that arylthioureas bearing electron-withdrawing groups at the para- (1bh), meta- (1i) and ortho- (1j, 1k) positions cyclised well, giving 73–89% isolated yields (Table [2], entries 2–8, 9, 10–11). However, electron-donating p-MeO (1l), p-Me (1m) substituents on the N-arylthiourea slowed the reaction and decreased the yields (Table [2], entries 12, 13). Presumably due to steric hindrance from the bulky alkylated amino group, the cyclisation yields of 2a, 2n and 2o decreased in turn, and substrate 1o and 1p, which bear two butyl groups on the nitrogen (Table [2], entries 15, 16), afforded the products in moderate yields (63% for 1o, 62% for 1p).

Table 1 Optimization of Model Reaction Conditionsa

Entry

Catalyst

Additive

Base

Solvent

Temp. (°C)

Yield (%)b

1

Cu(OAc)2

PhI

K2CO3

DMSO

100

0

2

CuO

PhI

K2CO3

DMSO

100

0

3

CuI

PhI

K2CO3

DMSO

100

0

4

PdCl2

PhI

K2CO3

DMSO

100

69

5

PdBr2

PhI

K2CO3

DMSO

100

64

6

Pd(dba)2

PhI

K2CO3

DMSO

100

54

7

Pd(PPh3)4

PhI

K2CO3

DMSO

100

N.R

8

Pd(OAc)2

PhI

K2CO3

DMSO

100

81

9

Pd(OAc)2

PhI

KOt-Bu

DMSO

100

N.R

10

Pd(OAc)2

PhI

Cs2CO3

DMSO

100

56

11

Pd(OAc)2

PhI

CH3ONa

DMSO

100

58

12

Pd(OAc)2

PhI

Na2CO3

DMSO

100

36

13

Pd(OAc)2

PhI

Et3N

DMSO

100

29

14

Pd(OAc)2

PhI

NaOH

DMSO

100

57

15

Pd(OAc)2

PhI

NaH

DMSO

100

44

16

Pd(OAc)2

4-iodotoluene

K2CO3

DMSO

100

69

17

Pd(OAc)2

1-iodo-4-nitrobenzene

K2CO3

DMSO

100

N.R

18

Pd(OAc)2

pyridine

K2CO3

DMSO

100

19

19

Pd(OAc)2

(i-Pr)2NEt

K2CO3

DMSO

100

17

20

Pd(OAc)2

KF

K2CO3

DMSO

100

trace

21

Pd(OAc)2

CsF

K2CO3

DMSO

100

trace

22

Pd(OAc)2

LiCl

K2CO3

DMSO

100

16

23

Pd(OAc)2

PhI

K2CO3

DMF

100

33

24

Pd(OAc)2

PhI

K2CO3

DMAC

100

27

25

Pd(OAc)2

PhI

K2CO3

PhCH3

100

trace

26

Pd(OAc)2

PhI

K2CO3

DMSO

110

72

27

Pd(OAc)2

PhI

K2CO3

DMSO

90

64

28

Pd(OAc)2

PhI

K2CO3

DMSO

80

44

a Reaction conditions: 1a (1.0 mmol), catalyst (10% mmol), additive (0.5 equiv), base (1.0 equiv), O2 (air), DMSO (2 mL) for 4–6 h.

b Isolated yield.

Table 2 Iodobenzene-Promoted Pd-Catalysed Synthesis of Benzothiazoles via an Intramolecular Couplinga

Entry

Substrate

Product

Time (h)

Yield (%)b

1

1a

2a

4.0

81

2

1b

2b

4.0

77

3

1c

2c

4.0

76

4

1d

2d

4.0

74

5

1e

2e

4.0

83

6

1f

2f

4.0

75

7

1g

2g

4.0

87

8

1h

2h

4.0

73

9

1i

2i

4.0

76

10

1j

2j

4.0

74

11

1k

2k

4.0

89

12

1l

2l

6.0

71

13

1m

2m

6.0

73

14

1n

2n

4.0

79

15

1o

2o

4.0

63

16

1p

2p

6.0

62

a Reaction conditions: 1 (1.0 mmol), catalyst (10% mmol), additive (0.5 mmol), base (1.0 mmol), O2 (air), DMSO (2 mL) for 4–6 h.

b Isolated yield.

In summary, we have presented an iodobenzene-promoted Pd-catalysed synthesis of benzothiazoles via an intramolecular coupling. A series of 2-aminobenzothiazoles was synthesised by a palladium-catalysed oxidative coupling in good yields (62–89%). Iodobenzene was found to be an effective additive in this intramolecular C–S bond-formation reaction. A directing group (thiourea) attached to the aryl ring is essential for activation of the ortho C–H. This protocol is experimentally simple and shows broad substrate scope, affording the 2-aminobenzothiazoles, and could be attractive in the fields of medicinal chemistry and materials science.

All reactions were carried out in dried glassware with septa. All starting materials were purchased from commercial suppliers. DMSO was dried over molecular sieves. Yields refer to isolated compounds estimated to be >95% pure as determined by 1H NMR and capillary GC analysis.

Typical Procedure for the Preparation of 2-Aminobenzothiazoles in the Presence of Iodobenzene and Palladium Diacetate

1,1-Dimethyl-3-phenylthiourea (1.0 mml), Pd(OAc)2 (10% mmol), K2CO (1.0 mmol), iodobenzene (0.5 mmol) were placed in a dried tube equipped with a septum and magnetic stirrer bar, and DMSO (2 mL) was then added. The mixture was stirred at 100 °C and the reaction was followed by TLC until the starting material was consumed (ca. 4–6 h). The reaction was cooled to r.t., quenched with sat. NH4Cl solution (5 mL) and then extracted with EtOAc (10 mL). The organic extract was dried over anhydrous Na2SO4, filtered and evaporated under vacuum. The residue was purified by flash column chromatography with a solvent system as described below to afford the desired product.


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N,N-Dimethylbenzo[d]thiazol-2-amine (Table [2], entry 1, 2a)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2a (144 mg, 81%) as a dark-yellow solid; mp 82–84 °C.

1H NMR (400 MHz, CDCl3): δ = 7.6 (t, J = 7.6 Hz, 2 H), 7.33 (t, J = 8.0 Hz, 1 H), 7.10 (t, J = 7.6 Hz, 1 H), 3.23 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 168.77, 153.08, 131.01, 125.98, 120.96, 120.66, 110.72, 40.22.

HRMS (ESI): m/z calcd for C9H10N2S: 178.0565; found: 178.0543.


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6-Bromo-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 2, 2b)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2b (198 mg, 77%) as a fawn solid; mp 109–112 °C.

1H NMR (400 MHz, CDCl3): δ = 7.66 (s, 1 H), 7.40–7.33 (m, 2 H), 3.17 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 168.81, 151.97, 132.61, 129.16, 123.11, 119.81, 113.20, 40.29.

HRMS (ESI): m/z calcd for C9H10N2S: 255.9670; found: 255.9681.


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6-Nitro-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 3, 2c)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:1) to give the target compound 2c (169 mg, 76%) as a bright-yellow solid; mp 209–211 °C.

1H NMR (400 MHz, CDCl3): δ = 8.44 (s, 1 H), 8.14 (d, J = 8.8 Hz, 1 H), 7.46 (d, J = 8.8 Hz, 1 H), 3.23 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 172.03, 158.37, 141.34, 131.21, 122.62, 117.79, 117.24, 40.43.

HRMS (ESI): m/z calcd for C9H10N2S: 223.0415; found: 224.0420.


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6-Nitrile-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 4, 2d)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:1) to give the target compound 2d (150 mg, 74%) as a grey solid; mp 162–164 °C.

1H NMR (400 MHz, CDCl3): δ = 7.79 (s, 1 H), 7.47 (s, 2 H), 3.30 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 170.97, 156.53, 131.63, 130.03, 124.75, 119.73, 118.76, 103.15.

HRMS (ESI): m/z calcd for C9H10N2S: 203.0517; found: 203.0519.


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6-Chloro-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 5, 2e)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2e (175 mg, 83%) as a brown solid; mp 102–104 °C.

1H NMR (400 MHz, CDCl3): δ = 7.46 (s, 1 H), 7.38 (d, J = 8.8 Hz, 1 H), 7.17 (d, J = 8.4, 1 H), 3.08 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 168.83, 151.72, 132.19, 126.38, 125.97, 120.29, 119.33, 40.36.

HRMS (ESI): m/z calcd for C9H10N2S; 212.0175; found: 212.0182.


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6-Fluoro-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 6, 2f)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2f (147 mg, 75%) as a white solid; mp 118–120 °C.

1H NMR (400 MHz, CDCl3): δ = 7.40–7.37 (m, 1 H), 7.19 (d, J = 8.0 Hz, 1 H), 6.92 (t, J = 8.0 Hz, 1 H), 3.03 (6 H).

13C NMR (100 MHz, CDCl3): δ = 168.33, 157.85 (d, 1 J C–F = 237.9 Hz), 149.34, 131.52 (d, 3 J C–F = 10.6 Hz), 119.04 (d, 3 J C–F = 8.6 Hz), 113.57 (d, 2 J C–F = 23.5 Hz), 107.40 (d, 2 J C–F = 26.8 Hz), 40.22.

HRMS (ESI): m/z calcd for C9H10N2S: 196.0470; found: 196.0468.


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6-Chloro-N,N-diethylbenzo[d]thiazol-2-amine (Table [2], entry 7, 2g)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:4) to give the target compound 2g (209 mg, 87%) as a pale-yellow syrup.

1H NMR (400 MHz, CDCl3): δ = 7.40 (s, 1 H), 7.26 (d, J = 8.8 Hz, 1 H), 7.09 (d, J = 8.4 Hz, 1 H), 3.46–3.40 (m, 4 H), 1.16 (t, J = 7.2 Hz, 6 H).

13C NMR (100 MHz, CDCl3): δ = 167.37, 151.76, 131.72, 126.16, 125.63, 120.13, 119.04, 45.46, 12.82.

HRMS (ESI): m/z calcd for C9H10N2S: 240.0488; found: 240.0475.


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6-Bromo-N,N-diethylbenzo[d]thiazol-2-amine (Table [2], entry 8, 2h)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:4) to give the target compound 2h (208 mg, 73%) as a pale-yellow syrup.

1H NMR (400 MHz, CDCl3): δ = 7.63 (s, 1 H), 7.36–7.31 (m, 2 H), 3.54–3.49 (m, 4 H), 1.24 (t, J = 7.2 Hz, 6 H).

13C NMR (100 MHz, CDCl3): δ = 167.40, 152.09, 132.21, 129.00, 122.98, 119.58, 112.90, 45.58, 1.07.

HRMS (ESI): m/z calcd for C9H10N2S: 283.9983; found: 283.9976.


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4-Bromo-N,N-diethylbenzo[d]thiazol-2-amine (Table [2], entry 9, 2i)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2i (188 mg, 73%) as a white solid; mp 116–118 °C.

1H NMR (400 MHz, CDCl3): δ = 7.62 (s, 1 H), 7.32 (d, J = 8.4 Hz, 1 H), 7.06 (d, J = 8.4 Hz, 1 H), 3.08 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 169.56, 154.61, 129.97, 123.55, 121.61, 119.41, 40.16.

HRMS (ESI): m/z calcd for C9H10N2S: 255.9670; found: 255.9678.


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4-Nitro-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 10, 2j)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2j (166 mg, 74%) as a brown solid; mp 199–201 °C.

1H NMR (400 MHz, CDCl3): δ = 7.98 (d, J = 8.4 Hz, 1 H), 7.74 (d, J = 7.6 Hz, 1 H), 7.02 (t, J = 8.0 Hz, 1 H), 3.24 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 171.10, 147.23, 138.66, 135.14, 125.80, 122.49, 119.42, 40.29.

HRMS (ESI): m/z calcd for C9H10N2S: 223.0415; found: 224.0409.


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4-Chloro-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 11, 2k)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:3) to give the target compound 2k (188 mg, 89%) as a white solid; mp 95–96 °C.

1H NMR (400 MHz, CDCl3): δ = 7.41 (d, J = 8.0 Hz, 1 H), 7.26 (d, J = 8.0 Hz, 1 H), 6.90 (t, J = 7.6 Hz, 1 H), 3.12 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 168.80, 150.21, 132.34, 126.18, 122.98, 121.18, 119.14, 40.15.

HRMS (ESI): m/z calcd for C9H10N2S: 212.0175; found: 212.0184.


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6-Methoxy-N,N-dimethylbenzo[d]thiazol-2-amine (Table [2], entry 12, 2l)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:1) to give the target compound 2l (148 mg, 71%) as a pale-yellow solid; mp 90–92 °C.

1H NMR (400 MHz, CDCl3): δ = 7.43 (d, J = 8.8 Hz, 1 H), 7.09 (s, 1 H), 8.85 (d, J = 8.4 Hz, 1 H), 3.75 (s, 3 H), 3.10 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 167.43, 154.66, 147.22, 131.86, 119.06, 113.49, 105.23, 55.87, 40.21.

HRMS (ESI): m/z calcd for C9H10N2S: 208.0670; found: 208.0682.


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N,N,6-Trimethylbenzo[d]thiazol-2-amine (Table [2], entry 13, 2m)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:1) to give the target compound 2m (126 mg, 73%) as a red-brown solid; mp 96–98 °C.

1H NMR (400 MHz, CDCl3): δ = 7.43 (d, J = 8.0 Hz, 1 H), 7.09 (d, J = 4.0 Hz, 1 H), 6.85 (d, J = 8.8 Hz, 1 H), 3.76 (s, 3 H), 3.10 (s, 6 H).

13C NMR (100 MHz, CDCl3): δ = 168.25, 150.92, 131.06, 130.61, 127.11, 120.72, 118.34, 40.19, 21.21.

HRMS (ESI): m/z calcd for C9H10N2S: 192.0721; found: 172.0729.


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N,N-Diethylbenzo[d]thiazol-2-amine (Table [2], entry 14, 2n)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:4) to give the target compound 2n (163 mg, 79%) as a pale-yellow syrup.

1H NMR (400 MHz, CDCl3): δ = 7.59 (t, J = 8.0 Hz, 2 H), 7.26 (t, J = 7.2 Hz, 1 H), 7.01 (t, J = 7.6 Hz, 1 H), 3.57–3.51 (m, 4 H), 1.26 (t, J = 7.2 Hz, 6 H).

13C NMR (100 MHz, CDCl3): δ = 167.30, 130.24, 125.93, 120.88, 120.56, 118.45, 45.54, 12.87.

HRMS (ESI): m/z calcd for C9H10N2S: 206.0878; found: 208.0885.


#

N,N-Dibutylbenzo[d]thiazol-2-amine (Table [2], entry 15, 2o)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:10) to give the target compound 2o (165 mg, 63%) as a colourless viscous oil.

1H NMR (400 MHz, CDCl3): δ = 7.54 (t, J = 8.0 Hz, 2 H), 7.25 (t, J = 8.0 Hz, 1 H), 7.01 (t, J = 8.0 Hz, 1 H), 3.48 (t, J = 8.0 Hz, 4 H), 1.70–1.63 (m, 4 H), 1.42–1.33 (m, 4 H), 0.96 (t, J = 8.0 Hz, 6 H).

13C NMR (100 MHz, CDCl3): δ = 167.90, 153.06, 130.52, 125.82, 120.71, 120.47, 118.51, 51.05, 29.64, 20.15, 13.96.

HRMS (ESI): m/z calcd for C9H10N2S: 262.1504; found: 262.1497.


#

6-Methoxy-N,N-dibutylbenzo[d]thiazol-2-amine (Table [2], entry 16, 2p)

The residue was purified by flash chromatography on silica gel (EtOAc/PE = 1:7) to give the target compound 2p (180 mg, 62%) as a pale-yellow syrup.

1H NMR (400 MHz, CDCl3): δ = 7.41 (d, J = 8.8 Hz, 1 H), 7.09 (s, 1 H), 6.84 (d, J = 9.2 Hz, 1 H), 3.76 (s, 3 H), 3.43 (t, J = 7.6 Hz, 4 H), 1.67–1.60 (m, 4 H), 1.38–1.32 (m, 4 H), 0.94 (t, J = 7.2 Hz, 6 H).

13C NMR (100 MHz, CDCl3): δ = 166.52, 154.50, 147.46, 131.50, 118.83, 113.19, 105.21, 55.88, 50.92, 26.69, 20.16, 13.96.

HRMS (ESI): m/z calcd for C9H10N2S: 292.1609; found: 292.1615.


#
#

Acknowledgment

We thank Prof. Aiwen Lei at Wuhan University for his generous support with provision of NMR spectroscopic analysis.

Supporting Information

  • References

  • 1 Hutchinson I. Chua M. J. Med. Chem. 1999; 42: 4173
  • 2 Šimonová E. Henselová M. Zahradník P. Plant. Soil Environ. 2005; 51: 496
  • 3 Bahrami K. Khodaei MM. Naali F. J. Org. Chem. 2008; 73: 6835
  • 4 Al-Qalaf F. Mekheimer RA. Sadek KU. Molecules 2008; 13: 2908
  • 5 Bahrami K. Khodaei MM. Naali F. Synlett 2009; 569
  • 6 Cao K. Tu YQ. Zhang FM. Sci. China Chem. 2010; 53: 130
  • 7 Khosravi K. Kazemi S. Chin. Chem. Lett. 2012; 23: 61
  • 8 Joyce LL. Evindar G. Batey RA. Chem. Commun. 2004; 446
  • 9 Benedi C. Bravo F. Uriz P. Fernández E. Claver C. Castillón S. Tetrahedron Lett. 2003; 44: 6073
  • 10 Jaseer EA. Prasad DJ. C. Dandapat A. Sekar G. Tetrahedron Lett. 2010; 51: 5009
  • 11 Joyce LL. Batey RA. Org. Lett. 2009; 11: 2792
  • 12 Inamoto K. Hasegawa C. Kawasaki J. Hiroya K. Doi T. Adv. Synth. Catal. 2010; 352: 2643
  • 13 Sharma S. Pathare RS. Maurya AK. Gopal K. Roy TK. Sawant DM. Pardasani RT. Org. Lett. 2016; 18: 356
  • 14 Wang H. Wang L. Shang J. Li X. Wang H. Gui J. Lei A. Chem. Commun. 2012; 48: 76
  • 15 Jordan AD. Luo C. Reitz AB. J. Org. Chem. 2003; 68: 8693

  • References

  • 1 Hutchinson I. Chua M. J. Med. Chem. 1999; 42: 4173
  • 2 Šimonová E. Henselová M. Zahradník P. Plant. Soil Environ. 2005; 51: 496
  • 3 Bahrami K. Khodaei MM. Naali F. J. Org. Chem. 2008; 73: 6835
  • 4 Al-Qalaf F. Mekheimer RA. Sadek KU. Molecules 2008; 13: 2908
  • 5 Bahrami K. Khodaei MM. Naali F. Synlett 2009; 569
  • 6 Cao K. Tu YQ. Zhang FM. Sci. China Chem. 2010; 53: 130
  • 7 Khosravi K. Kazemi S. Chin. Chem. Lett. 2012; 23: 61
  • 8 Joyce LL. Evindar G. Batey RA. Chem. Commun. 2004; 446
  • 9 Benedi C. Bravo F. Uriz P. Fernández E. Claver C. Castillón S. Tetrahedron Lett. 2003; 44: 6073
  • 10 Jaseer EA. Prasad DJ. C. Dandapat A. Sekar G. Tetrahedron Lett. 2010; 51: 5009
  • 11 Joyce LL. Batey RA. Org. Lett. 2009; 11: 2792
  • 12 Inamoto K. Hasegawa C. Kawasaki J. Hiroya K. Doi T. Adv. Synth. Catal. 2010; 352: 2643
  • 13 Sharma S. Pathare RS. Maurya AK. Gopal K. Roy TK. Sawant DM. Pardasani RT. Org. Lett. 2016; 18: 356
  • 14 Wang H. Wang L. Shang J. Li X. Wang H. Gui J. Lei A. Chem. Commun. 2012; 48: 76
  • 15 Jordan AD. Luo C. Reitz AB. J. Org. Chem. 2003; 68: 8693

Zoom Image
Scheme 1 Control experiments for the PhI-promoted synthesis of benzothiazole