Highly Diastereoselective Friedel−Crafts Reaction of Furans with 8-Phenylmenthyl Glyoxylate
2006 Vol. 8, No. 22 5045-5048
Piotr Kwiatkowski,† Jakub Majer,† Wojciech Chaładaj,† and Janusz Jurczak*,†,‡ Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland, and Department of Chemistry, Warsaw UniVersity, 02-093 Warsaw, Poland [email protected]
Received August 5, 2006
The Friedel−Crafts reaction of (1R)-8-phenylmenthyl glyoxylate with variously substituted furans was found to be efficiently promoted by SnCl4 or magnesium salts with high diastereoselectivities. MgBr2 performs especially well under simple, undemanding conditions, giving both high yields and high diastereoselectivities (>90%). The reaction afforded chiral substituted furan-2-yl-hydroxyacetic acid esters, compounds of potentially high synthetic interest.
The optically active furanyl R-hydroxyacetic acid esters (I) and products of their reductions, i.e., 1,2-diols of type II, are of great synthetic importance (Scheme 1).1 The latter
Scheme 1. Application of Furanyl R-Hydroxyacetic Derivatives or Corresponding Diols in the Synthesis
Polish Academy of Sciences. Warsaw University. (1) (a) Jurczak, J.; Kobrzycka, E.; Raczko, J. Pol. J. Chem. 1999, 73, 29. (b) Raczko, J. Pol. J. Chem. 1999, 73, 77. ‡
10.1021/ol061943p CCC: $33.50 Published on Web 10/06/2006
© 2006 American Chemical Society
alcohols, as a result of the presence of the furanyl moiety in their structure, can be easily converted under oxidizing conditions to very interesting linear (III)2 as well as cyclic products (IV)3,4 (Scheme 1). Such an approach was utilized, e.g., for the synthesis of multifunctional chain compounds2 or higher-carbon sugars.3 Diols bearing aryl substituents in position 5 were applied in the synthesis of spiroketal moiety of papulacandin D.4a They can be transformed also to amino alcohol derivatives of type V,5 leading under oxidizing conditions to dihydropyridones VI useful in the synthesis of aza sugars.5,6 The literature reports only a few methods for the synthesis of optically pure 2-furylcarbinols of type I. The most efficient methods rely on the enzymatic resolution of racemic mixtures using a lipase7 or on kinetic resolution using the Sharpless (2) Pikul, S.; Raczko, J.; Ankner, K.; Jurczak, J. J. Am. Chem. Soc. 1987, 109, 3981. (3) Achmatowicz, O., Jr.; Burzynska, M. H. Carbohydr. Res. 1985, 141, 67. (4) (a) Balachari, D.; O’Doherty, G. A. Org. Lett. 2000, 2, 863. (b) Harris, J. M.; Keranen, M. D.; O’Doherty, G. A. J. Org. Chem. 1999, 64, 2982. (5) Liao, L.-X.; Wang, Z.-M.; Zhang, H-X.; Zhou, W.-S. Tetrahedron: Asymmetry 1999, 10, 3649. (6) Haukaas, M. H.; O’Doherty, G. A. Org. Lett. 2001, 3, 401. (7) Zhang, W.; Wang, P. G. J. Org. Chem. 2000, 65, 4732.
Friedel-Crafts Reaction of Variously Substituted Furans with the Glyoxylate 1
reagent.8 The appropriate 1,2-diols of type II can be obtained via Sharpless asymmetric dihydroxylation of 5-substituted vinylfurans,4 and the simplest one of them, the unsubstituted diol (R ) H) can be obtained from the sugar derivatives (e.g., D-glucal).9 The most attractive methods appear to be direct ones employing a synthesis from the corresponding furans and aldehydes. Such an approach can be performed in two ways: by addition of lithiated furans to the carbonyl group or by the Lewis acid catalyzed Friedel-Crafts reaction. Until now, there was no effective diastereoselective10 or enantioselective11,12 synthetic method for furan derivatives of type I based on the latter approach. However, there are known examples of efficient diastereoselective13 and enantioselective11,14,15 Friedel-Crafts reactions of carbonyl compounds with other aromatic derivatives. Following our attempts to use chiral metallosalen complexes,12 we decided on more detailed investigation of the possibility of using chiral derivatives of glyoxylic acid. Until now, menthyl glyoxylate has been tried for this reaction,10,12b but as one could expect, it gave low asymmetric inductions. Because of that, we used its 8-phenylmenthyl derivative 116 (8) Kusakabe, M.; Kitano, Y.; Kobayashi, Y.; Sato, F. J. Org. Chem. 1989, 54, 2085. (9) Sobhana Babu, B. S.; Balasubramanian, K. K. J. Org. Chem. 2000, 65, 4198. (10) Jurczak, J.; Belniak, S.; Kozluk, T. Bull. Pol. Acad. Sci. 1991, 39, 271. (11) (a) Gathergood, N.; Zhuang, W.; Jørgensen, K. A. J. Am. Chem. Soc. 2000, 122, 12517. (b) Zhuang, W.; Gathergood, N.; Hazell, R. G.; Jørgensen, K. A. J. Org. Chem. 2001, 66, 1009. (12) (a) Kwiatkowski, P.; Wojaczynska, E.; Jurczak, J. Tetrahedron: Asymmetry 2003, 14, 3643. (b) Kwiatkowski, P.; Wojaczynska, E.; Jurczak, J. J. Mol. Catal. A: Chem. 2006, 257, 124. (13) Diastereoselective Friedel-Crafts reactions with chiral glyoxylates and pyruvates: (a) Bigi, F.; Casnati, G.; Sartori, G.; Dalprato, C.; Bortolini, R. Tetrahedron: Asymmetry 1990, 1, 861. (b) Bigi, F.; Bocelli, G.; Maggi, R.; Sartori, G. J. Org. Chem. 1999, 64, 5004. (c) Bigi, F.; Sartori, G.; Maggi, R.; Cantarelli, E.; Galaverna, G. Tetrahedron: Asymmetry 1993, 4, 2411. (d) Bigi, F.; Casiraghi, G.; Casnati, G.; Sartori, G.; Soncini, P.; Fava, G. G.; Belicchi, M. F. Tetrahedron Lett. 1985, 26, 2021. (e) Casiraghi, G.; Bigi, F.; Casnati, G.; Sartori, G.; Soncini, P.; Fava, G. G.; Belicchi, M. F. J. Org. Chem. 1988, 53, 1779. (f) Bauer, T.; Gajewiak, J. Synthesis 2004, 20. (14) For reviews on stereoselective Friedel-Crafts reactions, see: (a) Bandini, M., Melloni, A., Umani-Ronchi, A. Angew. Chem., Int. Ed. 2004, 43, 550. (b) Jørgensen, K. A. Synthesis 2003, 1117. (15) Selected enantioselective Friedel-Crafts reactions of aldehydes: (a) Ishii, A.; Kojima, J.; Mikami, K. Org. Lett. 1999, 1, 2013. (b) Ishii, A.; Soloshonok, V. A.; Mikami, K. J. Org. Chem. 2000, 65, 1597. (c) Yuan, Y.; Wang, X.; Li, X.; Ding, K. J. Org. Chem. 2004, 69, 146. (d) Corma, A.; Garcia, H.; Moussaif, A.; Sabatem, M. J.;Zniber, R.; Redouane, A. Chem. Commun. 2002, 1058. (e) Zhuang, W.; Poulsen, T. B.; Jørgensen, K. A. Org. Biomol. Chem. 2005, 3284. (f) Zhu, C.; Yuan, C.; Lv, Y. Synlett 2006, 1221. 5046
(Scheme 2). Glyoxylate 1 had been originally applied to the nucleophilic additions of organometallic species (e.g., Grignard reagents) and ene reaction by Whitesell.17,18 In the literature, there are also examples of application of the glyoxylate 1, e.g., in Diels-Alder,19 Morita-Baylis-Hillman,20 nitroaldol,21 allyl,22 and vinyl substitution reactions.23 Besides, it was also used by Bigi et al. in the Friedel-Crafts reaction, but only with phenols13a,b and O-protected phenols13c in the presence of TiCl4 or SnCl4, leading to 2- and 4-hydroxymandelic esters, respectively with high stereoselectivities. According to the literature, these Lewis acids are also the most efficient in other types of reactions with glyoxylate 1 (usually, 1 equiv is needed).18-23 In this paper, we describe a highly diastereoselective Friedel-Crafts reaction of (1R)-8-phenylmenthyl glyoxylate (1) with variously substituted furans 2a-n (Scheme 2, 14 examples). In our study, SnCl4 gave higher diastereoselectivities (>98% de) compared to those of TiCl4. We have studied extensively the reaction of 1 with benzyl furfuryl ether (2a), which was originally used by Achmatowicz in the total synthesis of racemic uloses.3 This reaction, in the presence of a stoichiometric amount of SnCl4, proceeds to give good yield and very high diastereoselectivity (Table 1, entry 1). We have tested also several other furan systems in this reaction, e.g., furan itself, and 2-methyl-, benzyl-, and phenyl-substituted furans, and each time we have observed also a very high diastereoselectivity (>99% de, Table 1, entries 2-6). This procedure can be successfully applied even to 2-trimethylsilylfuran (2j), unprotected furfuryl alcohol (2k), and furans bearing an electron-withdrawing group (2l) (16) (a) Whitesell, J. K.; Liu, C.-L.; Buchanan, C. M.; Chen, H.-H.; Minton, M. A. J. Org. Chem. 1986, 51, 551. (b) Ort, O. Org. Synth. 1987, 65, 203. (17) Whitesell, J. K.; Bhattacharya, A.; Henke, K. J. Chem. Soc., Chem. Commun. 1982, 988. (18) (a) Whitesell, J. K.; Bhattacharya, A.; Aguilar, D. A.; Henke, K. J. Chem. Soc., Chem. Commun. 1982, 989. (b) Whitesell, J. K.; Bhattacharya, A.; Buchanan, C. M.; Chen, H. H.; Deyo, D.; James, D.; Liu, C.-L.; Minton, M. A. Tetrahedron 1986, 42, 2993. (19) (a) Mulzer, J.; Meyer, F.; Buschmann, J.; Luger, P. Tetrahedron Lett. 1995, 36, 3503. (b) Kosior, M.; Asztemborska, M.; Jurczak, J. Synthesis 2004, 87. (20) Bauer, T.; Tarasiuk, J. Tetrahedron: Asymmetry 2001, 12, 1741. (21) (a) Solladie´-Cavallo, A.; Khiar, N. J. Org. Chem. 1990, 55, 4750. (b) Kudyba, I.; Raczko, J.; Urbanczyk-Lipkowska, Z.; Jurczak, J. Tetrahedron 2004, 60, 4807. (c) Kudyba, I.; Raczko, J.; Urbanczyk-Lipkowska, Z.; Jurczak, J. J. Org. Chem. 2004, 69, 2844. (22) (a) Yamamoto, Y.; Maeda, N.; Maruyama, K. J. Chem. Soc., Chem. Commun. 1983, 774. (b) Kiegiel, K.; Baakier, T.; Kwiatkowski, P.; Jurczak, J. Tetrahedron: Asymmetry 2004, 15, 3869. (23) Mikami, K.; Wakabayashi, H.; Nakai, T. J. Org. Chem. 1991, 56, 4337.
Org. Lett., Vol. 8, No. 22, 2006
Table 1. Friedel-Crafts Reaction of Furans with 1 Promoted by SnCl4a product entry
1 2 3 4 5 6 7 8 9
2a 2b 2c 2g 2h 2i 2j 2k 2l
5 2 2 2 2 4 2 2 5
3a 3b 3c 3g 3h 3i 3j 3k 3l
87 56 41 79 50 87 45 60 63
>99 >99 (S) >99 (S) >99 >99 >99 >99 >99 98
a The reactions were carried out using 0.5 mmol of the glyoxylate 1 in 3.0 mL of CH2Cl2, 1 equiv of SnCl4, and 1.5 equiv of furan at -78 °C. b Isolated yield. c Diastereomeric excess determined by HPLC and 1H NMR.
(entries 7-9). However, the yields were substantially lower (about 50%) in many cases, probably because of partial decomposition of the furan derivatives. Therefore, we decided to search for milder Lewis acids that would allow these reactions to be conducted efficiently and highly stereoselectively, c...