Abstract
A simple synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via one-pot four-component condensation reaction of phthalimide, hydrazine monohydrate, aromatic aldehyde derivatives and malononitrile in the presence of a catalytic amount of zirconium tetrachloride (ZrCl4) as a mild and efficient Lewis acidic catalyst under thermal and solvent-free conditions with good yields and short reaction times is developed. This present methodology has notable benefits such as high efficiency, inexpensive and non-toxic catalyst, environmentally benign nature, solvent-free conditions and simplicity of operation.
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
1 Introduction
In recent years, multi-component domino reactions (MCRs) (Strecker 1850; Rezayati et al. 2015; Saberi 2015; Hasaninejad et al. 2015; Hashemi and Sardarian 2013; Esmaeilpour and Sardarian 2013; Mohamadpour et al. 2016a, b, 2015) have become one of the best approaches for economical and efficient synthesis of organic compounds. The special advantages of multi-component reactions include simple work-up, atom-economy, mild and environment-friendly, low cost, one-pot for the synthesis of organic compounds. Therefore, our recent studies focused on developing multi-component reactions.
Recently, the study for the synthesis of nitrogen-containing heterocyclic compounds such as 1H-pyrazolo[1,2-b] phthalazine-5,10-dione derivatives has attracted considerable interest of organic chemists because of their special biological (Genin et al. 2000; Singh et al. 2004) (Fig. 1) and pharmacological properties, for example, antibacterial (inhibitory activity against Escherichia coli FabH) (Lu et al. 2010), anticancer (Li et al. 2006), anti-inflammatory (Ryu et al. 2007), and cardiotonic (Nomoto et al. 1990).
Biologically active compounds with two-ring junction nitrogen atom
Thus, recently, a number of procedures for the synthesis of 1H-pyrazolo[1,2-b] phthalazine-5, 10-dione derivatives have been reported that include Lewis and Brønsted acid catalysts, for example, Ce(SO4)2.4H2O (Mosaddegh and Hassankhani 2011), SBA-Pr-SO3H (MohammadiZiarani et al. 2014), InCl3 (VeeranarayanaReddy and TaeJeeong 2013), NiCl2.6H2O (Song et al. 2012), [Bmim] OH (Raghuvanshi and Singh 2011), ultrasound-assisted (Nabid et al. 2010), p-TSA (Sayyafi et al. 2008), STA (Veeranarayana Reddy et al. 2014), CuI nanoparticles (Safaei-Ghomi et al. 2014), p-TSA/[Bmim]Br (Ghahremanzadeh et al. 2008), and TBBAD (Ghorbani-Vaghei et al. 2014). Some of these methodologies have limitations such as long time of reactions, low yields, toxic and expensive catalysts, difficult work-up, and use of strongly acidic conditions. Because of our interest in the development of environment-friendly procedures for synthesis of these heterocyclic compounds, we have reported ZrCl4 as a mild and efficient catalyst for the one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives from reaction between phthalimide (1, 1.0 mmol), hydrazine monohydrate (2, 1.0 mmol), aromatic aldehyde derivatives (3, 1.0 mmol) and malononitrile (4, 1.0 mmol) under thermal and solvent-free conditions (Scheme 1). During the past decades, the use of zirconium compounds as environmentally safe catalysts in organic synthesis has attracted great interest due to their notable advantages such as non-toxic, environment-friendly, easy to handle, high efficiency and low cost (Zhang and Li 2009; Zhang et al. 2007). The advantages of using ZrCl4 as catalyst (Sajadikhah et al. 2015; Sharma et al. 2006) in organic compounds synthesis are mild, inexpensive, non-toxic, environmentally benign nature, and high catalytic activity. And we carried out the one-pot multi-component condensations by ZrCl4 in good yields and short reaction times.
Synthesis of 1H-pyrazolo[1,2-b] phthalazine-5,10-dione derivatives
Furthermore, one of the sources of environmental pollutions is the usage of organic solvents under reflux conditions and the need of column chromatography to purify the products. In this present work, the products were obtained through simple filtering with no need for column chromatographic separation.
2 Experimental
2.1 General
Melting points of all compounds were determined using an Electrothermal 9100 apparatus. Also, nuclear magnetic resonance, 1H NMR spectra were recorded on Bruker DRX-400 Avance instruments with DMSO-d6 as solvents. In this work, all reagents and solvents purchased from Merck, Fluka and Acros chemical companies were used without further purification.
2.2 General procedure for preparation of pyrazolo[1,2-b]phthalazine-5,10-dione derivatives (5a–o)
A mixture of hydrazine monohydrate (2, 1.0 mmol), phthalimide (1, 1.0 mmol), and ZrCl4 (20 mol%) was heated at 80 °C for 2 h. Then, malononitrile (4, 1.0 mmol) and aromatic aldehyde (3, 1.0 mmol) were added and the mixture of reaction was heated for appropriate time. After completion of the reaction (monitored by thin-layer chromatography, TLC), the mixture was cooled to rt, and the solid products were filtered and recrystallized from ethanol to give the corresponding products (5a–o). Spectra data of all products are represented below:
2.2.1 3-Amino-1-(phenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5a)
Yellow powder; yield: 87 %; m.p. 268–270 °C; 1H NMR (400 MHz, DMSO-d6): 6.14 (1H, s, Hbenzylic), 7.33–7.48 (5H, m, HAr), 7.97–8.29 (6H, m, NH2 and HAr).
2.2.2 3-Amino-1-(4-bromophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5b)
Yellow powder; yield: 80 %; m.p. 266–268 °C; 1H NMR (400 MHz, DMSO-d6): 6.14 (1H, s, Hbenzylic), 7.46 (2H, d, J = 11.2 Hz, HAr), 7.58 (2H, d, J = 11.2 Hz, HAr), 7.70–8.29 (6H, m, NH2 and HAr).
2.2.3 3-Amino-1-(2-nitrophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5c)
Yellow powder; yield: 83 %; m.p. 262–264 °C; 1H NMR (400 MHz, DMSO-d6): 6.62 (1H, s, Hbenzylic), 7.61 (1H, t, J = 9.6 Hz, HAr), 7.73 (1H, t, J = 9.6 Hz, HAr), 7.85–7.91 (2H, m, HAr), 7.97–8.30 (6H, m, NH2 and HAr).
2.2.4 3-Amino-1-(4-methylphenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5d)
Yellow powder; yield: 91 %; m.p. 255–257 °C; 1H NMR (400 MHz, DMSO-d6): 2.30 (3H, s, CH3), 6.10 (1H, s, Hbenzylic), 7.18 (2H, d, J = 8.0 Hz, HAr), 7.34 (2H, d, J = 8.0 Hz, HAr), 7.97–8.28 (6H, m, NH2 and HAr).
2.2.5 3-Amino-1-(2-chlorophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5e)
Yellow powder; yield: 81 %; m.p. 258–260 °C; 1H NMR (400 MHz, DMSO-d6): 6.47 (1H, s, Hbenzylic), 7.39–7.65 (4H, m, HAr), 7.91–8.31 (6H, m, NH2 and HAr).
2.2.6 3-Amino-1-(3-chlorophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5f)
Yellow powder; yield: 83 %; m.p. 267–269 °C; 1H NMR (400 MHz, DMSO-d6): 6.15 (1H, s, Hbenzylic), 7.39–7.41 (2H, m, HAr), 7.44–7.48 (1H, m, HAr), 7.65 (1H, s, HAr), 7.88–8.29 (6H, m, NH2 and HAr).
2.2.7 3-Amino-1-(2-thenaldehyde)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5g)
Yellow powder; yield: 88 %; m.p. 246–248 °C; 1H NMR (400 MHz, DMSO-d6): 6.09 (1H, s, Hbenzylic), 6.88–7.30 (4H, m, HAr), 7.96–8.28 (6H, m, NH2 and HAr).
2.2.8 3-Amino-1-(3-nitrophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5h)
Yellow powder; yield: 81 %; m.p. 270–272 °C; 1H NMR (400 MHz, DMSO-d6): 6.35 (1H, s, Hbenzylic), 7.57–7.90 (4H, m, HAr), 7.95–8.51 (6H, m, NH2 and HAr).
2.2.9 3-Amino-1-(3-methylphenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5i)
Yellow powder; yield: 94 %; m.p. 249–251 °C; 1H NMR (400 MHz, DMSO-d6): 2.30 (3H, s, CH3), 6.08 (1H, s, Hbenzylic), 7.14–7.26 (4H, m, HAr), 7.97–8.29 (6H, m, NH2 and HAr).
2.2.10 3-Amino-1-(4-nitrophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5j)
Yellow powder; yield: 84 %; m.p. 226–228 °C; 1H NMR (400 MHz, DMSO-d6): 6.30 (1H, s, Hbenzylic), 7.62–7.92 (4H, m, HAr), 7.96–8.45 (6H, m, NH2 and HAr).
2.2.11 3-Amino-1-(4-fluorophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5k)
Yellow powder; yield: 93 %; m.p. 262-264 °C; 1H NMR (400 MHz, DMSO-d6): 6.17 (1H, s, Hbenzylic), 7.20 (2H, t, J = 8.8 Hz, HAr), 7.53–7.57 (2H, m, HAr), 7.96–8.26 (6H, m, NH2 and HAr).
2.2.12 3-Amino-1-(3,4,5-trimethoxyphenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5l)
Yellow powder; yield: 79 %; m.p. 251–253 °C; 1H NMR (400 MHz, DMSO-d6): 3.66 (3H, s, OCH3), 3.76 (6H, s, 2 × OCH3), 6.07 (1H, s, Hbenzylic), 6.78 (2H, s, HAr), 7.89–8.29 (6H, m, NH2 and HAr).
2.2.13 3-Amino-1-(3-methoxyphenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5m)
Yellow powder; yield: 82 %; m.p. 249–251 °C; 1H NMR (400 MHz, DMSO-d6): 3.34 (3H, s, OCH3), 6.09 (1H, s, Hbenzylic), 6.88–7.30 (4H, m, HAr), 7.83–8.26 (6H, m, NH2 and HAr).
2.2.14 3-Amino-1-(4-chlorophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5n)
Yellow powder; yield: 86 %; m.p. 271–273 °C; 1H NMR (400 MHz, DMSO-d6): 6.15 (1H, s, Hbenzylic), 7.43 (2H, d, J = 11.2 Hz, HAr), 7.54 (2H, d, J = 11.2 Hz, HAr), 7.88–8.28 (6H, m, NH2 and HAr).
2.2.15 3-Amino-1-(3-fluorophenyl)-5,10-dihydro-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile (5o)
Yellow powder; yield: 91 %; m.p. 261–263 °C; 1H NMR (400 MHz, DMSO-d6): 6.16 (1H, s, Hbenzylic), 7.16–7.20 (1H, m, HAr), 7.33 (1H, d, J = 9.6 Hz, HAr), 7.39–7.46 (2H, m, HAr), 7.84–8.29 (6H, m, NH2 and HAr).
3 Results and Discussion
To carry out the preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives in a more efficient way, the reaction of phthalimide, hydrazine monohydrate, benzaldehyde and malononitrile was selected as a model system under thermal solvent-free conditions to find optimization of reaction conditions. The preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives was studied at different amounts of ZrCl4 as a mild and efficient Lewis acidic catalyst (5, 10, 15, 20 and 25 mol%) and different reaction temperatures (rt, 40, 60, 80 and 100 °C) (Table 1). The reaction did not occur in the absence of catalyst (Table 1, entry 1). The best result was obtained using 20 mol % of ZrCl4 at 80 °C (Table 1, entry 5). Using the optimized reaction conditions, the scope and efficiency of these procedures were explored for the synthesis of a wide variety of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives. The results are summarized in Table 2. As shown in Table 2, the direct four-component reactions worked well with a variety of arylaldehydes including those bearing electron-withdrawing and electron-donating groups such as Cl, Br, NO2, OMe, …, and the desired compounds were obtained in good to excellent yields. This methodology offers significant improvements such as simplicity in operation with no necessity of chromatographic purification steps, low-cost and eco-friendly catalyst.
The chemical structures of compounds (Table 2) were confirmed by melting point and 1H NMR spectroscopy. The structure of products was proved by comparison of spectroscopic data of some products with those of authentic samples (Table 3).
The proposed mechanism for the catalytic synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives in the presence of ZrCl4 is shown in Scheme 2. First, the reaction of phthalimide (1) with hydrazine monohydrate (2) produced phthalhydrazide (A). Next, in the catalytic system, the Knoevenagel-type coupling of arylaldehyde (3) and malononitrile (4) give rise to intermediate (B). Then, the subsequent 1,4-conjugate addition of phthalhydrazide (A) to the activated intermediate (B) followed by cyclization and tautomerization affords the corresponding product 5.
Proposed mechanistic route for the synthesis of pyrazolo[1,2-b]phthalazine-5,10-dione derivatives
Comparison of catalytic ability of some of the catalysts reported in the literature for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives is shown in Table 4. This study reveals that ZrCl4 has shown its extraordinary potential to be an alternative mild, low-cost and eco-friendly catalyst for the synthesis of these compounds; in addition to the use of solvent-free conditions, excellent yield and short reaction times in the reaction are the notable advantages of this present methodology.
4 Conclusion
In summary, zirconium tetrachloride (ZrCl4) as an efficient, eco-friendly Lewis acidic catalyst for the one-pot four-component clean synthesis of pyrazolo[1,2-b]phthalazine-5,10-dione derivatives by means of phthalimide, hydrazine monohydrate and the type of aldehydes derivatives, malononitrile under thermal and solvent-free conditions with excellent yields and short reaction times is studied. The notable advantages of the present methodology are low-cost and non-toxic catalyst, eco-friendly, mild, one-pot, highly efficient, environmentally benign nature, simplicity of operation with no necessity of chromatographic purification steps and solvent-free conditions.
References
Esmaeilpour M, Sardarian AZ (2013) 4-Dodecylbenzenesulfonic acid (DBSA): an efficient, eco-friendly and chemoselective catalyst for the synthesis of 1, 1-diacetates under solvent-free conditions at room temperature. Iran J Sci Technol 37:277–284
Genin MJ, Biles C, Keiser BJ, Poppe SM, Swaney SM, Tarpley WG, Yagi Y, Romero DL (2000) Novel 1, 5-diphenylpyrazole nonnucleoside HIV-1 reverse transcriptase inhibitors with enhanced activity versus the delavirdine-resistant P236L mutant: lead identification and SAR of 3- and 4-substituted derivatives. J Med Chem 43:1034–1040
Ghahremanzadeh R, Imani Shakibaei G, Bazgir A (2008) An Efficient One-Pot Synthesis of 1H-Pyrazolo [1, 2-b] phthalazine-5,10-dione. Synlett 8:1129–1132
Ghorbani-Vaghei R, Noori S, Toghraei-Semiromi Z, Salimi Z (2014) One-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives under solvent-free conditions. RSC Adv 4:47925–47928
Hasaninejad A, Yousefy T, Firoozi S (2015) Aluminium dodecyl sulfate trihydrate [Al(DS)3].3H2O: an efficient Lewis acid-surfactant-combined catalyst for synthesis of 1,8-dioxo-octahydroxanthens and 1,8-dioxo-decahydroacridines. Iran J Sci Technol 39:129–140
Hashemi H, Sardarian AR (2013) 4-Dodecylbenzenesulfonic acid (DBSA) as an efficient and recyclable catalyst for synthesis of 14-aryl- and 14-alkyl-14-H-dibenzo [a, j]xanthenes under solvent-free conditions. Iran J Sci Technol 37:75–82
Li J, Zhao YF, Yuan XY, Xu JX, Gong P (2006) Synthesis and anticancer activities of novel 1,4-disubstituted phthalazines. Molecules 11:574–582
Lu PC, Sun J, Luo Y, Yang Y, Zhu HL (2010) Design, synthesis and structure activity relationship of pyrazole derivatives as potential FabH inhibitors. Bioorg Med Chem Lett 20:4657–4660
Mohamadpour F, Maghsoodlou MT, Heydari R, Lashkari M (2015) Nano Zno: As an efficient and environmentally benign nature catalyst assisted one- pot four-component synthesis of polysubstituted dihydro-2-oxypyrroles. J Chem Pharm Res 7(11):941–944
Mohamadpour F, Maghsoodlou MT, Heydari R, Lashkari M (2016a) Saccharin: a green, economical and efficient catalyst for the one-pot, multi-component synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives and substituted dihydro-2-oxypyrrole. Iran J Chem Soc. doi:10.1007/s13738-016-0871-5
Mohamadpour F, Maghsoodlou MT, Heydari R, Lashkari M (2016b) Oxalic acid dihydrate catalyzed synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives under thermal and solvent-free conditions. Iran J Catal 6(2):127–131
MohammadiZiarani G, HosseiniMohtasham N, Badiei A, Lashgari N (2014) Efficient one-pot solvent-free synthesis of1H-pyrazolo[1,2-b]phthalazine-5,10-diones catalyzed by sulfonic acid functionalized nanoporous silica (SBA-Pr-SO3H). J Chin Chem Soc. doi:10.1002/jccs.201300538
Mosaddegh E, Hassankhani AA (2011) Rapid, one-pot, four-component route to 2H-indazolo [2, 1-b] phthalazine-triones. Tetrahedron Lett 52:488–490
Nabid MR, Rezaei SJT, Ghahremanzadeh R, Bazgir A (2010) Ultrasound-assisted one-pot, three-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones, Ultrason. Sonochem 17:159–161
Nomoto Y, Obase H, Takai H (1990) Studies on cardiotonic agents. II. Synthesis of novel phthalazine and 1, 2, 3-benzotriazine derivatives. Chem Pharm Bull (Tokyo) 38:2179–2183
Raghuvanshi DS, Singh KN (2011) A highly efficient green synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10-dione derivatives and their photophysical studies. Tetrahedron Lett 52:5702–5705
Rezayati S, Sajjadifar S, Hajinasiri R (2015) Chemoselective preparation of acylals using 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride as an efficient and reusable catalyst. Iran J Sci Technol 39:179–185
Ryu CK, Park RE, Ma MY, Nho JH (2007) Synthesis and antifungal activity of 6-arylamino-phthalazine-5,8-diones and 6,7-bis(arylthio)-phthalazine -5,8-diones. Bioorg Med Chem Lett 17:2577–2580
Saberi A (2015) Efficient synthesis of benzimidazoles using zeolite, alumina and silica gel under microwave irradiation. Iran J Sci Technol 39:7–10
Safaei-Ghomi J, Shahbazi-Alavi H, Ziarati A, Teymuri R, Saberi MR (2014) A highly flexible green synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10-dione derivatives with CuI nanoparticles as catalyst under solvent-free conditions. Chin Chem Lett 25:401–405
Sajadikhah SS, Maghsoodlou MT, Hazeri N, Mohamadian-Souri S (2015) ZrCl4 as an efficient catalyst for one-pot four-component synthesis of polysubstituted dihydropyrrol-2-ones. Res Chem Intermed. doi:10.1007/s11164-015-2178-z
Sayyafi M, Seyyedhamze M, Khavasi HR, Bazgir A (2008) One-pot, three-component route to 2H-indazolo [2, 1-b] phthalazine-triones. Tetrahedron 64:2375–2378
Sharma GVM, Jyothi Y, Lakshmi PS (2006) Efficient room-temperature synthesis of tri- and tetrasubstituted imidazoles catalyzed by ZrCl4. Syn Commun 36(20):2991–3000
Singh SK, Reddy PG, Rao KS, Lohray BB, Misra P, Rajjak SA, Rao YK, Venkatewarlu A (2004) Polar substitutions in the benzenesulfonamide ring of celecoxib afford a potent 1, 5-diarylpyrazole class of COX-2 inhibitors. Bioorg Med Chem Lett 14:499–504
Song SH, Zhong J, He YH, Guan Z (2012) One-pot four-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives. Tetrahedron Lett 53:7075–7077
Strecker A (1850) Ueber die künstliche Bildung der Milchsäure und einen neuen, dem Glycocoll homologen Körper. Leibigs Ann Chem 7:27–45
Veeranarayana Reddy M, ChennaRohiniKumar P, ChandraSekhar Reddy G, Suresh Reddy C (2014) Silica gel-supported tungstic acid (STA): a new, highly efficient and recyclable catalyst for the synthesis of 1H -pyrazolo[1,2-b]phthalazine-5,10-dione carbonitriles and carboxylates under neat conditions. C R Chimie 17:1250–1256
VeeranarayanaReddy M, TaeJeeong Y (2013) InCl3-catalyzed green synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10- diones under solvent-free conditions. Tetrahedron Lett 54:3546–3549
Zhang ZH, Li TS (2009) Applications of zirconium (IV) compounds in organic synthesis. Curr Org Chem 13:1–30
Zhang ZH, Li TS, Li JJ (2007) Synthesis of enaminones and enamino esters catalysed by ZrOCl2· 8H2O. Catal Commun 8:1615–1620
Acknowledgments
We gratefully acknowledge financial support from the Research Council of University of Sistan and Baluchestan.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lashkari, M., Heydari, R. & Mohamadpour, F. A Facile Approach for One-Pot Synthesis of 1H-pyrazolo [1,2-b]phthalazine-5,10-dione Derivatives Catalyzed by ZrCl4 as an Efficient Catalyst Under Solvent-Free Conditions. Iran J Sci Technol Trans Sci 42, 1191–1197 (2018). https://doi.org/10.1007/s40995-016-0122-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40995-016-0122-8