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Metallophthalocyanines catalyzed cyclopropanation of olefins with trimethylsilyldiazomethane: A facile and stereoselective synthesis of silylcyclopropanes
Catalysis Communications 7 (2006) 454–456 www.elsevier.com/locate/catcom
Metallophthalocyanines catalyzed cyclopropanation of olefins with trimethylsilyldiazomethane: A facile and stereoselective synthesis of silylcyclopropanes Vishal B. Sharma, Suman L. Jain, Bir Sain
*
Chemical and Biotechnology Division, Indian Institute of Petroleum, Mohkampur, Dehradun, UA 248 005, India Received 8 September 2005; received in revised form 20 December 2005; accepted 21 December 2005 Available online 9 March 2006
Abstract Metallophthalocyanines were found to be potent and versatile catalysts for the stereoselective synthesis of C-silyl cyclopropanes with high trans-selectivity by the reaction of olefins with trimethylsilyldiazomethane. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Silylcyclopropanes; Metallophthalocyanines; Trimethylsilyldiazomethane; Cyclopropanation; Olefin
1. Introduction Cyclopropanes are versatile intermediates in organic synthesis that can be converted to a variety of useful products by cleavage of the strained three membered ring [1]. C-silylcyclopropanes in particular are very important compounds as silyl group can be replaced by various elecrophiles and also it can control the nucleophilic ring opening transformations [2]. The transition metal catalyzed decomposition of trimethylsilyldiazomethane (TMSCHN2) in the presence of olefins is a simple and direct method for the synthesis of C-silyl-cyclopropanes. Despite of the cyclopropanation of olefins with diazoesters there are few reports are available in the literature for the cyclopropanation with trimethylsilyldiazomethane. In this context, transition metal catalysts such as [Ru2(CO)4(l-OAc)2 [3], CuCl [4], Copper (I) bis oxazoline [5] and iron (II) complexes [6] have been reported. The use of heterogeneous or heterogenized homogeneous catalysts for synthetic transformations is an area of current interest due to ease of separation and recycling of the catalyst. To the best of our knowledge, there is no literature report on the use of heterogeneous catalysts for the cyclo*
Corresponding author. Tel.: +91 135 2660071; fax: +91 135 2660202. E-mail address: [email protected] (B. Sain).
1566-7367/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2005.12.027
propanation of olefins using trimethylsilyldiazomethane as carbenoid precursor. Metallophthalocyanines, which are structurally similar to metalporphyrines, are easily accessible, quite stable and can be easily separated from the reaction mixture for reuse, have been extensively used to catalyze a variety of organic reactions [7–12]. In continuation to our studies herein [13–22], we report for the first time the use of metallophthalocyanines (MPc) as potent and superior catalysts for the cyclopropanation of olefins with trimethylsilyldiazomethane (Scheme 1). 2. Experimental 2.1. Materials Copper, iron, manganese, nickel and cobaltphthalocyanines were prepared according to the literature procedures. All olefins used were commercially available and distilled before use. 2 M solution in hexane of trimethylsilyldiazomethane was used and purchased from Aldrich. 2.2. General experimental procedure To a stirred solution of olefin (2 mmol) in 1,2 dichloroethane (5 ml) containing Cu (II) phathalocyanine
V.B. Sharma et al. / Catalysis Communications 7 (2006) 454–456
R1
R3
R2
R4
Metallo phthalo cyanine, ClCH2CH2Cl TMSCHN2, N2, (Reflux)
R1
R3
R2
R4 Si(CH3)3
Scheme 1.
Table 1 Copper (II) phthalocyanine catalyzed cyclopropanation of olefins with TMSCHN2b Entry
Olefin
Reaction time (h)
Yielda (%)
1 2 3 4 5 6 7 8 9 10
Styrene 4-Methylstyrene 3-Methylstyrene a-Methylstyrene Methylmethacrylate trans Methylcinnamate Vinylcyclohexane Cyclohexene Cycloheptene 4-Chlorostrene
5.5 5.0 5.5 5.0 7.5 7.5 8.5 6.5 7.0 8.5
62 70 65 67 50 40 48 55 45 35
a
Isolated yields. Copper (II) phthalocyanine (5 mol%), olefin/TMSCHN2 (2:5)1,2dichloroethane (5 ml) under N2 atmosphere at refluxing temperature. b
(0.05 mmol, 5 mol%), was added trimethylsilyldiazomethane (5 mmol) drop wise for a period of 0.5 h under nitrogen atmosphere. The reaction mixture was refluxed and progress of the reaction was monitored by TLC. After completion of the reaction the catalyst was removed by filtration and the filtrate obtained was evaporated under vacuum to give an oil, which was purified by passing through the silica gel column using (hexane/ethyl acetate, 4:1) as eluent. Evaporation of the solvent yielded the mixture of corresponding cis and trans trimethylsilyl cyclopropane. In case of the reaction of styrene and 4-methyl styrene with trimethylsilyldiazomethane using Cu (II) Pc as catalyst the diastereomers were separated by thin layer chromatography and obtained trans-products predominantly. The diastereoselectivity of the products were confirmed by comparing the spectral data (IR and 1H NMR) with those of authentic samples reported in the literature [3,23]. Similarly other silyl cyclopropanes were formed and their reaction times and yields are presented in Table 1. 3. Results and discussion The protocol developed for the cyclopropanation of olefins consists the drop wise addition of trimethylsilyldiazomethane (5 mmol) in the stirred mixture of olefin (2 mmol) and copper (II) phthalocyanine (CuPc) in dry 1,2-dichloromethane (5 ml) for the period of 0.5 h under the nitrogen atmosphere. All the olefins studied were smoothly converted to their corresponding silyl cyclopropnanes and results are presented in Table 1. The diastereoselectivity of the cyclopropanes were determined by separating the cis and trans silyl cyclopropanes from the
455
Table 2 Cyclopropanation of 4-methylstyrene by TMSCHN2 using different metal phthalocyanines as catalystsb Entry
Substrate
Catalyst (5 mol %)
Yielda (%)
1 2 3 4 5
4-Methylstyrene 4-Methylstyrene 4-Methylstyrene 4-Methylstyrene 4-Methylstyrene
Cu (II) Pc Fe (II) Pc Mn (II) Pc Ni (II) Pc Co (II) Pc
70 65 45 20 10
a
Isolated yields. Experiments were carried out under similar reaction conditions as mentioned in text. Reaction time 5 h. b
reaction of styrene and 4-methylstyrene with TMSCHN2 by thin layer chromatography and obtained trans products predominantly. This was confirmed by comparing the spectral data (1H NMR and IR) with those of authentic samples obtained by using CuCl as catalyst, which is known to give, trans products mainly [3,23]. To evaluate the catalytic efficiency of various metallophthalocyanines, the reaction of 4-methylstyrene with TMSCHN2 was studied by using different metallophthalocyanines as catalysts and dichloroethane as solvent. These results are summarized in Table 2 and show that Cu (II) phthalocyanine [Cu (II) Pc] is the most active catalyst followed by Fe (II)-phthalocyanines. Mn (II), Ni (II)-and Co (II)-phthalocyanines were found to be very less active for this reaction. The cyclopropanation of 4-methylstyrene with TMSCHN2 was also carried out in different solvent like xylene, benzene, 1,2-dichloroethane, acetonitrile under similar reaction condition. Among the various solvents studied, dichloroethane was found to be best solvent for these reactions. The effect of the temperature was also studied for the cyclopropanation of olefins with trimethylsilyldiazomethane, using 4-methyl styrene as substrate. The reaction was found to be slow at room temperature, while the addition of the TMSCHN2 at room temperature followed by refluxing increases the reaction rates as well as yields of the silyl cyclopropanes. Copper and other metallophthalocyanine catalysts used in these reactions could be easily recovered by filtration and reused several times without any significant loss in their activity. Although mechanism of this reaction is not clear at this stage, the reaction probably involves the formation of metal-carbenoid species followed by the transfer of carbene to olefin to yield cyclopropane. 4. Conclusion In summary, we have demonstrated for the first time copper and iron phthalocyanines to be highly efficient heterogeneous catalysts for cyclopropanation of olefins using trimethylsilyldiazomethane as carbene precursor. The simple preparation, easy separation of the catalyst, simple workup and better yields of silyl cyclopropanes make the metallophthalocyanines ideal heterogeneous catalysts for cyclopropanation of olefins.
456
V.B. Sharma et al. / Catalysis Communications 7 (2006) 454–456
Acknowledgments We are thankful to Director, IIP for his kind permission to publish these results. Suman L. Jain and Vishal B. Sharma are thankful to CSIR, New Delhi, for the award of research fellowship. References [1] H.N.C. Wong, M.-Y. Hon, C.-W. Tse, Y.C. YiP, J. Tanko, T. Hudlicky, Chem. Rev. 89 (1989) 165. [2] L.A. Paquette, Chem. Rev. 86 (1986) 733. [3] G. Mass, J. Seitz, Tetrahedron Lett. 42 (2001) 6137. [4] M.B. France, A.K. Milojevich, T.A. Stitt, A.J. Kim, Tetrahedron Lett. 44 (2003) 9287. [5] D. Seyferth, H. Manzel, A.W. Dow, T.C. Flood, J. Organomet. Chem. 44 (1972) 279. [6] C.G. Hamaker, G.A. Mirafzal, L.K. Woo, Organometallics 20 (2001) 5171.
[7] C. Perollier, A.B. Sorokin, Chem. Commun. (2002) 1548. [8] B. Meunier, A. Sorokin, Accounts Chem. Res. 30 (1997) 470. [9] A. Sorokin, S. De Suzzoni-Dezard, S.D. Poullain, J.P. Noel, B. Meunier, J. Am. Chem. Soc. 118 (1996) 7418. [10] A. Hadasch, A. Sorokin, B. Meunier, J. Chem. Soc., Chem. Commun. (1994) 1799. [11] A. Sorokin, A. Rabion, L. Fraisse, B. Meunier, Bull. Soc. Chim. Fr. 134 (1997) 1025. [12] A. Sorokin, J.L. Seris, B. Meunier, Science 268 (1995) 1163. [13] V.B. Sharma, S.L. Jain, B. Sain, Catal. Lett. 94 (2004) 57. [14] S.L. Jain, B. Sain, Angew. Chem., Int. Ed. 42 (2003) 1265. [15] S.L. Jain, B. Sain, Chem. Commun. (2002) 1040. [16] S.L. Jain, B. Sain, J. Mol. Catal. 176 (2001) 101. [17] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 383. [18] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 3235. [19] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 2655. [20] S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 575. [21] S.L. Jain, V.B. Sharma, B. Sain, Tetrahedron Lett. 44 (2003) 4385. [22] S.L. Jain, V.B. Sharma, B. Sain, Tetrahedron Lett. 45 (2004) 1233. [23] D. Seyferth, A.W. Dow, H. Menzel, T.C. Flood, J. Am. Chem. Soc. 90 (1968) 1080.
Metallophthalocyanines catalyzed cyclopropanation of olefins with trimethylsilyldiazomethane: A facile and stereoselective synthesis of silylcyclopropanes Vishal B. Sharma, Suman L. Jain, Bir Sain
*
Chemical and Biotechnology Division, Indian Institute of Petroleum, Mohkampur, Dehradun, UA 248 005, India Received 8 September 2005; received in revised form 20 December 2005; accepted 21 December 2005 Available online 9 March 2006
Abstract Metallophthalocyanines were found to be potent and versatile catalysts for the stereoselective synthesis of C-silyl cyclopropanes with high trans-selectivity by the reaction of olefins with trimethylsilyldiazomethane. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Silylcyclopropanes; Metallophthalocyanines; Trimethylsilyldiazomethane; Cyclopropanation; Olefin
1. Introduction Cyclopropanes are versatile intermediates in organic synthesis that can be converted to a variety of useful products by cleavage of the strained three membered ring [1]. C-silylcyclopropanes in particular are very important compounds as silyl group can be replaced by various elecrophiles and also it can control the nucleophilic ring opening transformations [2]. The transition metal catalyzed decomposition of trimethylsilyldiazomethane (TMSCHN2) in the presence of olefins is a simple and direct method for the synthesis of C-silyl-cyclopropanes. Despite of the cyclopropanation of olefins with diazoesters there are few reports are available in the literature for the cyclopropanation with trimethylsilyldiazomethane. In this context, transition metal catalysts such as [Ru2(CO)4(l-OAc)2 [3], CuCl [4], Copper (I) bis oxazoline [5] and iron (II) complexes [6] have been reported. The use of heterogeneous or heterogenized homogeneous catalysts for synthetic transformations is an area of current interest due to ease of separation and recycling of the catalyst. To the best of our knowledge, there is no literature report on the use of heterogeneous catalysts for the cyclo*
Corresponding author. Tel.: +91 135 2660071; fax: +91 135 2660202. E-mail address: [email protected] (B. Sain).
1566-7367/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2005.12.027
propanation of olefins using trimethylsilyldiazomethane as carbenoid precursor. Metallophthalocyanines, which are structurally similar to metalporphyrines, are easily accessible, quite stable and can be easily separated from the reaction mixture for reuse, have been extensively used to catalyze a variety of organic reactions [7–12]. In continuation to our studies herein [13–22], we report for the first time the use of metallophthalocyanines (MPc) as potent and superior catalysts for the cyclopropanation of olefins with trimethylsilyldiazomethane (Scheme 1). 2. Experimental 2.1. Materials Copper, iron, manganese, nickel and cobaltphthalocyanines were prepared according to the literature procedures. All olefins used were commercially available and distilled before use. 2 M solution in hexane of trimethylsilyldiazomethane was used and purchased from Aldrich. 2.2. General experimental procedure To a stirred solution of olefin (2 mmol) in 1,2 dichloroethane (5 ml) containing Cu (II) phathalocyanine
V.B. Sharma et al. / Catalysis Communications 7 (2006) 454–456
R1
R3
R2
R4
Metallo phthalo cyanine, ClCH2CH2Cl TMSCHN2, N2, (Reflux)
R1
R3
R2
R4 Si(CH3)3
Scheme 1.
Table 1 Copper (II) phthalocyanine catalyzed cyclopropanation of olefins with TMSCHN2b Entry
Olefin
Reaction time (h)
Yielda (%)
1 2 3 4 5 6 7 8 9 10
Styrene 4-Methylstyrene 3-Methylstyrene a-Methylstyrene Methylmethacrylate trans Methylcinnamate Vinylcyclohexane Cyclohexene Cycloheptene 4-Chlorostrene
5.5 5.0 5.5 5.0 7.5 7.5 8.5 6.5 7.0 8.5
62 70 65 67 50 40 48 55 45 35
a
Isolated yields. Copper (II) phthalocyanine (5 mol%), olefin/TMSCHN2 (2:5)1,2dichloroethane (5 ml) under N2 atmosphere at refluxing temperature. b
(0.05 mmol, 5 mol%), was added trimethylsilyldiazomethane (5 mmol) drop wise for a period of 0.5 h under nitrogen atmosphere. The reaction mixture was refluxed and progress of the reaction was monitored by TLC. After completion of the reaction the catalyst was removed by filtration and the filtrate obtained was evaporated under vacuum to give an oil, which was purified by passing through the silica gel column using (hexane/ethyl acetate, 4:1) as eluent. Evaporation of the solvent yielded the mixture of corresponding cis and trans trimethylsilyl cyclopropane. In case of the reaction of styrene and 4-methyl styrene with trimethylsilyldiazomethane using Cu (II) Pc as catalyst the diastereomers were separated by thin layer chromatography and obtained trans-products predominantly. The diastereoselectivity of the products were confirmed by comparing the spectral data (IR and 1H NMR) with those of authentic samples reported in the literature [3,23]. Similarly other silyl cyclopropanes were formed and their reaction times and yields are presented in Table 1. 3. Results and discussion The protocol developed for the cyclopropanation of olefins consists the drop wise addition of trimethylsilyldiazomethane (5 mmol) in the stirred mixture of olefin (2 mmol) and copper (II) phthalocyanine (CuPc) in dry 1,2-dichloromethane (5 ml) for the period of 0.5 h under the nitrogen atmosphere. All the olefins studied were smoothly converted to their corresponding silyl cyclopropnanes and results are presented in Table 1. The diastereoselectivity of the cyclopropanes were determined by separating the cis and trans silyl cyclopropanes from the
455
Table 2 Cyclopropanation of 4-methylstyrene by TMSCHN2 using different metal phthalocyanines as catalystsb Entry
Substrate
Catalyst (5 mol %)
Yielda (%)
1 2 3 4 5
4-Methylstyrene 4-Methylstyrene 4-Methylstyrene 4-Methylstyrene 4-Methylstyrene
Cu (II) Pc Fe (II) Pc Mn (II) Pc Ni (II) Pc Co (II) Pc
70 65 45 20 10
a
Isolated yields. Experiments were carried out under similar reaction conditions as mentioned in text. Reaction time 5 h. b
reaction of styrene and 4-methylstyrene with TMSCHN2 by thin layer chromatography and obtained trans products predominantly. This was confirmed by comparing the spectral data (1H NMR and IR) with those of authentic samples obtained by using CuCl as catalyst, which is known to give, trans products mainly [3,23]. To evaluate the catalytic efficiency of various metallophthalocyanines, the reaction of 4-methylstyrene with TMSCHN2 was studied by using different metallophthalocyanines as catalysts and dichloroethane as solvent. These results are summarized in Table 2 and show that Cu (II) phthalocyanine [Cu (II) Pc] is the most active catalyst followed by Fe (II)-phthalocyanines. Mn (II), Ni (II)-and Co (II)-phthalocyanines were found to be very less active for this reaction. The cyclopropanation of 4-methylstyrene with TMSCHN2 was also carried out in different solvent like xylene, benzene, 1,2-dichloroethane, acetonitrile under similar reaction condition. Among the various solvents studied, dichloroethane was found to be best solvent for these reactions. The effect of the temperature was also studied for the cyclopropanation of olefins with trimethylsilyldiazomethane, using 4-methyl styrene as substrate. The reaction was found to be slow at room temperature, while the addition of the TMSCHN2 at room temperature followed by refluxing increases the reaction rates as well as yields of the silyl cyclopropanes. Copper and other metallophthalocyanine catalysts used in these reactions could be easily recovered by filtration and reused several times without any significant loss in their activity. Although mechanism of this reaction is not clear at this stage, the reaction probably involves the formation of metal-carbenoid species followed by the transfer of carbene to olefin to yield cyclopropane. 4. Conclusion In summary, we have demonstrated for the first time copper and iron phthalocyanines to be highly efficient heterogeneous catalysts for cyclopropanation of olefins using trimethylsilyldiazomethane as carbene precursor. The simple preparation, easy separation of the catalyst, simple workup and better yields of silyl cyclopropanes make the metallophthalocyanines ideal heterogeneous catalysts for cyclopropanation of olefins.
456
V.B. Sharma et al. / Catalysis Communications 7 (2006) 454–456
Acknowledgments We are thankful to Director, IIP for his kind permission to publish these results. Suman L. Jain and Vishal B. Sharma are thankful to CSIR, New Delhi, for the award of research fellowship. References [1] H.N.C. Wong, M.-Y. Hon, C.-W. Tse, Y.C. YiP, J. Tanko, T. Hudlicky, Chem. Rev. 89 (1989) 165. [2] L.A. Paquette, Chem. Rev. 86 (1986) 733. [3] G. Mass, J. Seitz, Tetrahedron Lett. 42 (2001) 6137. [4] M.B. France, A.K. Milojevich, T.A. Stitt, A.J. Kim, Tetrahedron Lett. 44 (2003) 9287. [5] D. Seyferth, H. Manzel, A.W. Dow, T.C. Flood, J. Organomet. Chem. 44 (1972) 279. [6] C.G. Hamaker, G.A. Mirafzal, L.K. Woo, Organometallics 20 (2001) 5171.
[7] C. Perollier, A.B. Sorokin, Chem. Commun. (2002) 1548. [8] B. Meunier, A. Sorokin, Accounts Chem. Res. 30 (1997) 470. [9] A. Sorokin, S. De Suzzoni-Dezard, S.D. Poullain, J.P. Noel, B. Meunier, J. Am. Chem. Soc. 118 (1996) 7418. [10] A. Hadasch, A. Sorokin, B. Meunier, J. Chem. Soc., Chem. Commun. (1994) 1799. [11] A. Sorokin, A. Rabion, L. Fraisse, B. Meunier, Bull. Soc. Chim. Fr. 134 (1997) 1025. [12] A. Sorokin, J.L. Seris, B. Meunier, Science 268 (1995) 1163. [13] V.B. Sharma, S.L. Jain, B. Sain, Catal. Lett. 94 (2004) 57. [14] S.L. Jain, B. Sain, Angew. Chem., Int. Ed. 42 (2003) 1265. [15] S.L. Jain, B. Sain, Chem. Commun. (2002) 1040. [16] S.L. Jain, B. Sain, J. Mol. Catal. 176 (2001) 101. [17] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 383. [18] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 3235. [19] V.B. Sharma, S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 2655. [20] S.L. Jain, B. Sain, Tetrahedron Lett. 44 (2003) 575. [21] S.L. Jain, V.B. Sharma, B. Sain, Tetrahedron Lett. 44 (2003) 4385. [22] S.L. Jain, V.B. Sharma, B. Sain, Tetrahedron Lett. 45 (2004) 1233. [23] D. Seyferth, A.W. Dow, H. Menzel, T.C. Flood, J. Am. Chem. Soc. 90 (1968) 1080.