NovaJournal Rifatul Ulya,of Chemical Sabirin Technology Matsjeh, Winarto and Metallurgy, Haryadi, 54,Dewanto 4, 2019, Harjunowibowo 733-741

SYNTHESIS OF 1-BENZYL-3-METHYL-6,7-DIMETHOXY-3,4- DIHYDROISOQUINOLINE TO BE USED AS A POTENTIAL HYBRID DRUG

Nova Rifatul Ulya1, Sabirin Matsjeh1, Winarto Haryadi1, Dewanto Harjunowibowo2,3

1 Department of Chemistry, Universitas Gadjah Mada, Yogyakarta-55281, Indonesia Received 15 March 2018 2 Department of Physics Education, Accepted 08 March 2019 Universitas Sebelas Maret, Surakarta-57126, Indonesia 3 Department of Architecture and Built Environment, The University of Nottingham Nottingham-NG7 2RD, United Kingdom E-mail: [email protected]

ABSTRACT

The existence of multiple functional groups in isoquinoline derivatives determines their potential as drug compounds. This research aims at the synthesis of such new isoquinoline based products. The compound 1-benzyl- 3-methyl-6,7-dimethoxy-3,4-dihydroisoquinoline containing methyl, methoxy, and benzyl groups has a potential of simultaneous acting antitumour, antimalarial and antivirus properties. Its synthesis from eugenol methyl ether is achieved through the latter conversion to a secondary alcohol, followed by Ritter reaction with benzyl cyanide and a cyclization reaction of the amide obtained to isoquinoline using sulfuric acid. The addition reaction between eugenol methyl ether and formic acid yields 1-(3,4-dimethoxyphenyl)-2-propyl formate (86,46 %). Its hydrolysis with KOH results in the formation of 1-(3,4-dimethoxyphenyl)-2-propanol (86,4 %). The latter reaction with benzyl cyanide in the course of Ritter reaction yields N-[1-benzyl-2-(3,4-dimethoxyphenyl)ethyl]-2-phenyl-acetamide (34,70 %). The subsequent cyclization with sulfuric acid and purification results in 1-benzyl-3-methyl-6,7-dimethoxy-3,4- dihydroisoquinoline as the main target with an yield of 45.19 %. An experimental verification of the corresponding products obtained is provided by FTIR, 1H-NMR, and GC-MS. Keywords: isoquinoline, eugenol methyl ether, Ritter reaction, synthesise.

INTRODUCTION derivatives and α-methylene-γ-butyrolactones to the tumour cells. Eugenol methyl ether is the main component of the It is well recognized that isoquinoline is an active clove oil methylation product [1]. It contains an alkyl drug compound as it has cytotoxicity against leukaemia group which can undergo derivatisation through several [7], antitumour [8, 9] and antimalarial properties [10]. reactions. Their products can be used as a starting It has antivirus and antihypertensive effects [11]. It is material in the synthesis of other compounds [2]. Eugenol also used in Parkinson syndrome treatment [12]. The methyl ether participates in the synthesis of isoquinoline antitumour (6,7-dimethoxy-3,4-dihydroisoquinoline- derivatives through a conversion to a secondary alcohol 2-(1H)il-(3,4-dimethoxyphenyl)-methanone is shown along the Ritter reaction and a cyclization with sulfuric in Fig. 1. It contains 3,4-dimethoxybenzoyl substituent acid [3]. According to Lednicer dan Mitsher [4] the bonded to the ketone group in the N-atom heterocyclic isoquinoline derivatives have an activity of drug ring which improves the antitumour activity expected. compounds determined by the coexistence of an aromatic Iwasa et al. [10] synthesize 1-(3,4-diethoxybenzyl)- system and six-membered heterocyclic rings. Yang et al. 6,7-diethoxy-2,3-dimethyl-isoquinoline, where the [5, 6] develop a carrier agent which delivers isoquinoline existence of a methyl group at C3 in the heterocyclic 733 Journal of Chemical Technology and Metallurgy, 54, 4, 2019

Fig. 3. A structural formula of an isoquinoline com- Fig. 1. A structural formula of (6,7-dimethoxy-3,4- pound [11]. dihydroisoquinoline-2-(1H)il-(3,4- dimethoxyphenyl)- Sohilait [2] uses eugenol methyl ether to synthesize methanone [9]. 3,4-dimethoxyphenyl-2-propanone as a reactant in preparation of L-α-Methyl DOPA (α-methyl hydroxyphe-nylalanine) compound used as an antihypertensive and Parkinson drug. Farid [3] uses eugenol methyl ether to synthesize 1,3-dimethyl-6,7- dimethoxy-3,4-dihydroisoquinoline derivative through four steps referring to an addition, a hydrolysis, Ritter reaction, and a cyclization. In the course of the Ritter reaction the amide compound reacts with acetonitrile and is then cyclisized. That isoquinoline derivative obtained Fig. 2. A structural formula of 1-(3,4-diethoxybenzyl)-6,7- has a potential as an antihypertensive drug [3]. diethoxy-2,3-dimethyl-isoquinoline [10]. The consideration presented above shows that if the three isoquinoline derivatives can be merged, ring improves the antimalarial activity observed. The the product obtained may have simultaneously acting structural formula of 1-(3,4-diethoxybenzyl)-6,7- antitumour, antimalarial, and antivirus properties. The diethoxy-2,3-dimethyl-isoquinoline is presented in Fig. existence of those functional groups might provide the 2. A synthesis and an isoquinoline derived compound creation of a multi-function drug. This investigation activation test is done by Cui et al. [11] where the aims to synthesise 1-benzyl-3-methyl-6,7-dimethoxy- existence of a methoxy group provides an antivirus 3,4-dihydroisoquinoline compound from eugenol methyl activity (Fig. 3) . ether. The reaction scheme is presented in Fig. 4.

Fig. 4. A scheme of isoquinoline synthesis. 734 Nova Rifatul Ulya, Sabirin Matsjeh, Winarto Haryadi, Dewanto Harjunowibowo

EXPERIMENTAL organic layer was dehydrated with Na2SO4 anhydrate, filtered, and evaporated using Buchi evaporator. The Material and Methods extract concentrate was purified by a vacuum distillation Eugenol methyl ether, formic acid (HCOOH), in the temperature range of 130oC - 135oC (~ 30 mm diethyl ether, natrium bicarbonate (NaHCO3), natrium Hg). The distillate obtained was analysed using IR 1 sulfate (Na2SO4) anhydrite, potassium hydroxide (KOH), spectrophotometry, GC-MS, and H-NMR. ethanol (C2H5OH), sulfuric acid (H2SO4), benzyl chloride

(C7H7Cl), cyanide natrium (NaCN), benzyl cyanide Synthesis of 1-(3,4-dimethoxyphenyl)-2-propanol

(C7H7CN), dichloromethane (CH2Cl2), acetic acid KOH (0.18 mol) was dissolved in 10 mL of

(CH3COOH), methanol (CH3OH), and distilled water distilled water and 10 mL of ethanol. The solution were used in this study. was introduced to a two-necks flask provided with a The equipment required referred to a reflux unit set, a magnetic stirrer and a funnel containing 0.09 mol of distillation unit, a hot plate stirrer, and Buchi evaporator. 1-(3,4-dimethoxyphenyl)-2-propyl formate. The reaction

IR Shimadzu Prestige-21, GC-MS Shimadzu QP-2010S, was performed for 2 h at a room temperature. H2SO4 was 1 and H-NMR 400 MHz with CDCl3 as a solvent were added to neutralise the mixture. Then an extracttion with used to analyze the products obtained. diethyl ether was carried out The extract was collected,

dried with anhydrous Na2SO4, filtered and evaporated. General Procedures The concentrated extract obtained was analysed by IR Synthesis of 1-(3,4-dimethoxyphenyl)-2-propyl formate spectrophotometry, GC-MS, and 1H-NMR. Formic acid (7.29 mol) was added to eugenol methyl ether (0.27 mol) and refluxed continuously for 21.5 h. Synthesis of N-[1-methyl-2-(3,4-dimethoxyphenyl) The product was distilled at temperature 100oC -105oC to ethyl]-2-phenyl acetamide get 1-(3,4-dimethoxyphenyl)-2-propyl formate solution. Benzyl cyanide (0.08 mol) dissolved in (0.08 mol) of

The resulting material was neutralised with concentrated acetic acid was added to 17 mL of concentrated H2SO4

NaHCO3 and then extracted with diethyl ether. The and 0.08 mol of a solution of 1-(3,4-dimethoxyphenyl)-

Fig. 5. 1H-NMR spectrum of 1-(3,4-dimethoxyphenyl)-2-propyl formate.

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Table 1. Data derived from the 1H-NMR spectrum of 1-(3,4-dimethoxyphenyl)-2-propyl formate. Number chemical shift (δ) Appearance number of Proton-type ppm protons a 7.889 Singlet 1 OCHO b 6.631-6.709 Singlet 3 H Aromatic

c 5.104-5.119 Multiplet 1 R2CHOCHO

d 3.743-3.762 Singlet 6 ArOCH3

e 2.581-2.792 Doublet 2 -CH2

f 1.121-1.172 Doublet 3 -CH3

2-propanol. The reaction was performed at a room RESULTS AND DISCUSSION temperature for 96 h. Subsequently, saturated NaHCO3 Synthesis of 1-(3,4-dimethoxyphenyl)-2-propyl formate was added until a neutral pH value was achieved. Then The reaction of Eugenol methyl ether with formic acid an extraction with dichloromethane was carried out. The gives a reaction product of 1-(3,4-dimethoxyphenyl)- extract was collected, dried with anhydrous Na2SO4 and 2-propyl formate with an yield of 86.46 %. The FTIR then filtered. The residue obtained was analysed by IR spectrum (cm-1) analysis shows 2935-2836 (-CH-alkyl); spectrophotometry and GC-MS. 1716 (C = O ester); 1515 (C = C aromatic); 1461 (-CH2- ); 1379 (-CH3); and 1264-1184 (C-O-C ester). The Synthesis of 1-benzyl-3-methyl-6,7-dimethoxy-3,4- 1H-NMR (ppm) analysis shows δ = 1.121 to 1.172 (d, dihydroisoquinoline -CH3); δ = 2.581 to 2.792 (d, -CH2-); δ = 3.743 to 3.762 N-[1-methyl-2-(3,4-dimethoxyphenyl)ethyl]- (s, ArOCH3); δ = 5.104 to 5.119 (m, R2CHOCHO); δ = 2-phenyl acetamide (0.008 mol) dissolved in 10 ml 6.631 to 6.709 (s, H aromatic); δ = 7.889 (s, -OCHO). 1 dichloromethane was placed in a flask. 1 mL of 2H SO4 Table 1 and Fig. 5 illustrate the H-NMR spectra was added dropwise while stirring. The reaction was interpretation. The six areas of chemical shifts indicate conducted at a temperature of 50°C for 2 h. Upon its that the synthesised compound has 6 different protons. completion saturated NaHCO3 was added until a neutral The data of the GC chromatogram (Fig. 6) indicates a pH value was reached. This step was followed by an dominant peak of 94.53 %. That information is reinforced extraction with dichloromethane. The product obtained by the MS analysis results which show a molecular ion + was collected, dried with Na2SO4 anhydrate and filtered. (M ) of m/z of 224. The latter value is attributed to the The filtrate was evaporated and the residue obtained was molecular weight of 1-(3,4-dimethoxyphenyl)-2-propyl analysed by IR spectrophotometry and GC-MS. formate (Fig. 7).

Fig. 6. GC-MS chromatogram of 1-(3,4-dimethoxyphenyl) -2-propyl formate.

736 Nova Rifatul Ulya, Sabirin Matsjeh, Winarto Haryadi, Dewanto Harjunowibowo Relative Intensity, % Relative Intensity,

m/z Fig. 7. MS data referring to1-(3,4-dimethoxyphenyl)-2-propyl formate.

Fig. 8. 1H-NMR spectrum of 1-(3,4-dimethoxyphenyl)-2-propanol.

Synthesis of 1-(3,4-dimethoxyphenyl)-2-propanol 95.81 % of the dominant peak observed (Fig. 9). This The hydrolysis product of 1-(3,4-dimethoxyphenyl)- result is verified by the MS analysis showing the presence 2-propyl formate and KOH refers to 1-(3,4-dimethoxy- of a molecular ion (M+) of m/z of 196. It is attributed phenyl)-2-propanol. Its yield amounts to 86.41%. The to the molecular mass of 1-(3,4-dimethoxyphenyl)-2- FTIR spectrum (cm-1) shows 3415 (OH); 2933-2836 propanol (Fig. 10).

(-CH-alkyl); 1516 (C = C aromatic); 1464 (-CH2-); 1372 1 (-CH3). The H-NMR (ppm) analysis shows δ = 1.123 to Synthesis of N-[1-methyl-2-(3,4-dimethoxyphenyl)

1.164 (d, -CH3); δ = 2.237 (s, OH); δ = 2.570 to 2.634 (d, ethyl]-2-phenyl acetamide

-CH2-); δ = 3.592 to 3.921 (s, OCH3); δ = 4.754 (m, R2- The synthesis of N-[1-methyl-2-(3,4-dimethoxy- CHOH); δ = 6.669 to 6.756 (s, Ar-H). Fig. 8 shows that phenyl)ethyl]-2-phenyl acetamide is carried out through the synthesised compound has 6 different protons. This the reaction of 1-(3,4-dimethoxyphenyl)-2-propanol with is evident from the 6 signals in the area of the chemical benzyl cyanide. The yield obtained amounts to 34.70 %. shifts outlined in the 1H-NMR spectrum (Table 2). The FTIR spectrum analysis (Fig. 11) reveals 3326 The GC chromatogram data shows a grading of (-NH secondary amide); 2931-2839 (-CH-alkyl); 1666-

737 Journal of Chemical Technology and Metallurgy, 54, 4, 2019

Table 2. 1H-NMR spectrum data referring to 1-(3,4-dimethoxyphenyl)-2-propanol. Number chemical shift (δ) Appearance number of Proton-type ppm protons a 6.669-6.756 Singlet 3 Ar-H

b 4.754 Multiplet 1 R2-CHOH

c 3.592-3.921 Singlet 6 -OCH3

d 2.570-2.634 Doublet 2 -CH2 e 2.237 Singlet 1 -OH

f 1.123-1.164 Doublet 3 -CH3

Fig. 9. GC-MS chromatogram of 1-(3,4-dimethoxyphenyl)- 2-propanol. Relative Intensity, % Relative Intensity,

m/z Fig. 10. MS data referring to 1-(3,4-dimethoxyphenyl)-2-propanol.

1566 (C = O amide), and 1604-1512 (C = C aromatic). compounds using sulfuric acid as a catalyst. In this case The GC chromatogram shows a dominant peak of 58.08 N-[1-methyl-2-(3,4-dimethoxyphenyl)ethyl]-2-phenyl % (Fig. 12). It refers to the product of the Ritter reaction. acetamide reacts with sulfuric acid to give 1-benzyl- A verification is provided by the MS analysis which 3-methyl-6,7-dimethoxy-3,4-dihydroisoquinoline shows a molecular ion (M+) of m/z of 313 corresponding compound. This cyclization reaction gives a product of to the molecular weight of N-[1-methyl-2-(3,4- an yield of 39 % before purification. After purification, dimethoxyphenyl)ethyl]-2 phenyl acetamide (Fig. 13). it is analysed by FTIR (Fig. 14) and GC-MS (Fig. 15). The FTIR spectrum (cm-1) analysis shows 3101 Synthesis of 1-benzyl-3-methyl-6,7-dimethoxy-3,4- (-CH-aromatic); 2924-2854 (-CH-alkyl); 1612 (C = N dihydroisoquinoline heterocyclic); and 1604-1512 (C = C aromatic). There is The synthesis of isoquinoline compound is achieved a weak absorption at 3356 cm-1 which indicates that the through a cyclization reaction between the amide amide compound has not completely reacted. The GC 738 Nova Rifatul Ulya, Sabirin Matsjeh, Winarto Haryadi, Dewanto Harjunowibowo

Fig. 11. FTIR spectrum of N-[1-methyl-2-(3,4-dimethoxyphenyl)ethyl]-2 phenyl acetamide.

Fig. 12. GC-MS chromatogram of the Ritter reaction products. Relative Intensity, % Relative Intensity,

m/z Fig. 13. MS data referring to the Ritter reaction products.

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Fig. 14. FTIR spectrum of isoquinoline.

Fig. 15. GC-MS chromatogram of isoquinoline. Relative Intensity, % Relative Intensity,

m/z Fig. 16. MS data referring to isoquinoline.

740 Nova Rifatul Ulya, Sabirin Matsjeh, Winarto Haryadi, Dewanto Harjunowibowo

chromatogram obtained after purification of the product and Sons, 1984. (Fig. 15) shows five peaks referring to five compounds 5. X. Yang, S. Yang, H. Chai, Z. Yang, R.J. Lee, W. obtained by the cyclization reaction. It can be easily Liao, et al., A Novel Isoquinoline Derivative Anti- identified that peaks 2 and 3 attributed to a molecular cancer Agent and Its Targeted Delivery to Tumor weight of 313 refer to the amide compound N-[1-methyl- Cells Using Transferrin-Conjugated Liposomes, 2-(3,4-dimethoxyphenyl)ethyl]-2-phenyl acetamide PLoS One, 2015 Jan,10, 8, e0136649. that has not been fully cyclisized. The dominant peak 6. T-Y. Qin, W-W. Liao, Y-J. Zhang, SX-A. Zhang, of 45.19 % refers to 1-benzyl-3-methyl-6,7-dimethoxy- Asymmetric organocatalytic allylic alkylation of 3,4-dihydroisoquinoline compound. The data presented Reissert compounds: a facile access to chiral 1, is validated by the MS analysis (Fig. 16) which shows a 1-disubstituted 1, 2-dihydroisoquinolines, Org. molecular ion of m/z of 295. This mass is identified as Biomol. Chem., 11, 6, 2013, 984-990. that of the isoquinoline compound. 7. P. Pudjiastuti, M.R. Mukhtar, A.H.A. Hadi, N. Saidi, H. Morita, M. Litaudon, et al. (6,7-Dimeth- CONCLUSIONS oxy-4-methylisoquinolinyl)-(4’-methoxyphenyl)- The study is focused at the synthesis of a potential methanone, a new benzylisoquinoline alkaloid hybrid drug based on isoquinoline and eugenol methyl from beilschmiedia brevipes, Molecules, 2010;15, ether as a reactant. The process takes place through an 4, 2010, 2339-2346. addition, a hydrolysis, Ritter reaction, and cyclization. 8. K.H. Kim, I.K. Lee, C.J. Piao, S.U. Choi, J.H. Lee, The purification of 1-benzyl-3-methyl-6,7-dimethoxy- Y.S. Kim, et al., Benzylisoquinoline alkaloids from 3,4-dihydroisoquinoline is successfully obtained with the tubers of Corydalis ternata and their cytotoxicity, an yield of 45.19 %. The compound has a potential Bioorganic Med. Chem. Lett. [Internet]. 2010;20, of an antitumour, antimalarial, and anti-virus drug. It 15, 2010, 4487-4490, a SX-A vailable from: http:// requires further purification and clinical trials prior to dx.doi.org/10.1016/j.bmcl.2010.06.035 its application to a human organism. 9. H. Hatano, F. Takekawa, K. Hashimoto, M. Ishi- hara, M. Kawase, C. Qing, et al., Tumor-specific Acknowledgements cytotoxic activity of 1,2,3,4-tetrahydroisoquino- The authors would like to thank PT INDESSO line derivatives against human oral squamous cell AROMA, Indonesia for the material support provided. carcinoma cell lines, Anticancer Res. [Internet], 2009;29, 8, 2009, 3079-3086, available from: http:// REFERENCES ar.iiarjournals.org/content/29/8/3079.full.pdf 10. K. Iwasa, M. Moriyasu, Y. Tachibana, H.S. Kim, Y. 1. H. Sastrohamidjojo, Kimia Minyak Atsiri, Yogya- Wataya, W. Wiegrebe, et al., Simple isoquinoline and karta, Gadjah Mada University Press, 2004. benzylisoquinoline alkaloids as potential antimicro- 2. H.J. Sohilait, Sintesis Senyawa Ester Format dari bial, antimalarial, cytotoxic, and anti-HIV agents, Eugenol dan Metileugenol, J. Sigma, 5, 2, 2002, Bioorganic Med. Chem., 9, 11, 2001, 2871-2884. 4-45. 11. W. Cui, K. Iwasa, H. Tokuda, A. Kashihara, Y. 3. M.R. Farid, S. Matsjeh, R.D. Soelistyowati, Syn- Mitani, T. Hasegawa, et al., Potential cancer thesis of 1,3-Dimethyl-6,7-Dimethoxy-3,4-Dihy- chemopreventive activity of simple isoquinolines, droisoquinoline via Cyclodehydration reaction, in: 1-benzylisoquinolines, and protoberberines, Phyto- Proceeding of International Seminar on Organic chemistry, 2006;67, 1, 2006, 70-79. Chemistry, Yogyakarta, 2001. 12. H.J. Sohilait, Sintesis 3,4-Dimethoxy Fenil-2-Pro- 4. D. Lednicer, L.A. Mitscher, The Organic Chemistry panon dari Metil Eugenol, Sigma, SX-A SX-A 6, 2, of Drug Synthesis, 3rd ed., v. 3. Canada, John Wiley 2003, 193-196.

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