Regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles and their cholinesterase inhibitory activities

Khan, Maria Aqeel; Fazal-Ur-Rehman, Saba; Hameed, Abdul; Kousar, Shazia; Dalvandi, Kourosh; Yousuf, Sammer; Choudhary, M. Iqbal; Basha, Fatima Z.

doi:10.1039/c5ra10461k

Cited by 12 publications

(31 citation statements)

References 29 publications

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“…The reaction between l -menthol and phenyl hydrazine was also performed in the newly developed DABCO-IL-based DES to get the corresponding indole. The product obtained in l -methanol was identified as indolenine rather than indole and is in agreement with the previous reports . The requisite cyclization to furnish tricycle ring system occurs at isopropyl-substituted carbon to form indolenine 7g as the major isomer and 7h as the minor isomer .…”

Section: Results and Discussionsupporting

confidence: 90%

“…The product obtained in l -methanol was identified as indolenine rather than indole and is in agreement with the previous reports. 14 The requisite cyclization to furnish tricycle ring system occurs at isopropyl-substituted carbon to form indolenine 7g as the major isomer and 7h as the minor isomer. 14 The formation of such a hindered and substituted product confirms the validity of new catalytic DES melts for its application as safe and green reaction media for organic syntheses.…”

Section: Results and Discussionmentioning

confidence: 99%

“…(2R,4aR)-4a-Isopropyl-2-methyl-2,3,4,4a-tetrahydro-1H-carbazole (7g). 14 Following the general procedure, the reaction was performed, and the corresponding compounds (7g and 7h) were isolated by using preparative HPLC with the eluant mixture of EtOAc and hexane (4:6). Yield 39% 1 H NMR (300 MHz, DMSO): δ H 7.44 (1H, d, J = 7.5 Hz, ArH), 7.36 (1H, d, J = 7.5 Hz, ArH), 7.28 (1H, t, J = 6.6 Hz, ArH), 7.13 (1H, t, J = 7.4 Hz, ArH), 2.64 (1H, dd, J = 13.2, 3.3 Hz, CH), 2.49 (1H, m, obscured by H 2 O signal, CH), 2.36 (1H, quint, J = 6.9 Hz, CH), 2.28 (1H, t, J = 12.3 Hz, CH), 1.53−1.51 (3H, m, CH 2 −CHH), 1.16 (3H, d, J = 6.9 Hz, CH 3 ), 1.09 (3H, d, J = 5.4 Hz, CH 3 ), 0.88−0.78 (1H, m, CH), 0.12 (3H, d, J = 6.9 Hz, CH 3 ); MS-EI m/z 227.2 (M + ).…”

Section: Acs Omegamentioning

confidence: 99%

“…(2R,4aS)-4a-Isopropyl-2-methyl-2,3,4,4a-tetrahydro-1H-carbazole (7h). 14 Yield 25% 1 H NMR (300 MHz, DMSO): δ H 7.46 (1H, d, J = 7.8 Hz, ArH), 7.36 (1H, d, J = 7.2 Hz, ArH), 7.28 (1H, td, J = 7.5, 0.9 Hz, ArH), 7.13 (1H, t, J = 7.2 Hz, ArH), 2.77 (1H, dd, J = 12.9, 6.0 Hz, CH), 2.42−2.32 (3H, m, CH 2 −CHH), 2.02 (1H, tt, J = 14.2, 4.2 Hz, CH), 1.30 (1H, app dd, J = 14.1, 1.8 Hz, CH), 1.16 (3H, d, J = 6.9 Hz, CH 3 ), 1.05 (1H, td, J = 14.1, 3.9 Hz, CH), 0.71 (3H, d, J = 7.2 Hz, CH 3 ), 0.11 (3H, d, J = 6.6 Hz, CH 3 ); MS-EI m/z 227.2 (M + ).…”

Section: Acs Omegamentioning

confidence: 99%

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N-Alkylated 1,4-Diazabicyclo[2.2.2]octane–Polyethylene Glycol Melt as Deep Eutectic Solvent for the Synthesis of Fisher Indoles and 1H-Tetrazoles

et al. 2017

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1,4-Diazabicyclo[2.2.2]octane (DABCO)-based ionic liquids (ILs) 2–4 were synthesized by the N-alkylation of DABCO using alkyl halides of varying chain lengths (C 2 , C 5 , and C 7 ). The N-alkylated DABCO-ILs were mixed with polyethylene glycols (PEGs) of varying molar masses as hydrogen bond donors (HBDs) to prepare new deep eutectic solvents (DESs). These DABCO–PEG-based DESs were successfully employed for the synthesis of a variety of indoles 7a–7h (by Fischer indole synthesis) and 1 H -tetrazoles 9a–9i (by click chemistry). For comparison, DESs of DABCO-ILs with different alcohols (as HBD) were also prepared and investigated for the synthesis of indoles. Although comparable yields were observed in DES-containing alcohols and PEGs, the use of PEG as HBD in DES (as an alternative to alcohols) provides a much safer, nonvolatile, and environmentally benign reaction medium for synthetic reactions. The first successful application of PEG-polymer-based DES as benign reaction media for organic syntheses offers exciting opportunities to be explored in the realm of green synthesis.

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Section: Results and Discussionsupporting

confidence: 90%

Section: Results and Discussionmentioning

confidence: 99%

Section: Acs Omegamentioning

confidence: 99%

Section: Acs Omegamentioning

confidence: 99%

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N-Alkylated 1,4-Diazabicyclo[2.2.2]octane–Polyethylene Glycol Melt as Deep Eutectic Solvent for the Synthesis of Fisher Indoles and 1H-Tetrazoles

et al. 2017

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“…These agents are important drugs for palliative treatment of AD, but their clinical efficacy is limited due to their poor selectivity, bioavailability and adverse side effects. Thus, there is an urgent need for developing new effective, multifunctional anti‐AD drugs …”

Section: Introductionmentioning

confidence: 99%

Synthesis, biological evaluation, and docking studies of some 5‐chloro‐2(3H)‐benzoxazolone Mannich bases derivatives as cholinesterase inhibitors

Uysal

Parlar

Tarikogullari

et al. 2018

Archiv der Pharmazie

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A series of N-substituted-5-chloro-2(3H)-benzoxazolone derivatives were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory, and antioxidant activities. The structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellman's colorimetric method. The free radical scavenging activity was also determined by in vitro ABTS (2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) assay. The biological activity results revealed that all of the title compounds displayed higher AChE inhibitory activity than the reference compound, rivastigmine, and were selective for AChE. Among the tested compounds, compound 7 exhibited the highest inhibition against AChE (IC = 7.53 ± 0.17 μM), while compound 11 was found to be the most active compound against BuChE (IC = 17.50 ± 0.29 μM). The molecular docking study of compound 7 showed that this compound can interact with the catalytic active site (CAS) of AChE and also has potential metal chelating ability and a proper log P value. On the other hand, compound 2 bearing a methyl substituent at the ortho position on the phenyl ring showed better radical scavenging activity (IC = 1.04 ± 0.04 mM) than Trolox (IC = 1.50 ± 0.05 mM).

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ChemInform Abstract: Regioselective Synthesis of Novel 2,3,4,4a‐Tetrahydro‐1H‐carbazoles and Their Cholinesterase Inhibitory Activities.

et al. 2015

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Regioselective Synthesis of Novel 2,3,4,4a-Tetrahydro-1H-carbazoles and Their Cholinesterase Inhibitory Activities. -The carbazoles are synthesized from L-menthone and substituted phenyl hydrazines in acetic acid and show promising inhibitory activities against acetyl-and butyrylcholinesterase. -(KHAN, M. A.; FAZAL-UR-REHMAN, S.; HAMEED, A.; KOUSAR, S.; DALVANDI, K.; YOUSUF, S.; CHOUDHARY, M. I.; BASHA*, F. Z.; RSC Adv. 5 (2015) 73, 59240-59250, http://dx.doi.org/10.1039/C5RA10461K ; Int. Cent. Chem. Biol. Sci., H. E. J. Res. Inst. Chem., Univ. Karachi, Karachi 75270, Pak.; Eng.) -L. Grundl 49-113

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Regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles and their cholinesterase inhibitory activities

Abstract: The present study describes the regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles (syn-2(a–q) and anti-3(a–b)) from l-menthone via Fischer indole synthesis.

Cited by 12 publications

References 29 publications

N-Alkylated 1,4-Diazabicyclo[2.2.2]octane–Polyethylene Glycol Melt as Deep Eutectic Solvent for the Synthesis of Fisher Indoles and 1H-Tetrazoles

N-Alkylated 1,4-Diazabicyclo[2.2.2]octane–Polyethylene Glycol Melt as Deep Eutectic Solvent for the Synthesis of Fisher Indoles and 1H-Tetrazoles

Synthesis, biological evaluation, and docking studies of some 5‐chloro‐2(3H)‐benzoxazolone Mannich bases derivatives as cholinesterase inhibitors

ChemInform Abstract: Regioselective Synthesis of Novel 2,3,4,4a‐Tetrahydro‐1H‐carbazoles and Their Cholinesterase Inhibitory Activities.

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