摘要:

J. CHEM. SOC. PERKIN TRANS. 2 1995 Self-assembly of tetracationic amphiphiles bearing a calixC41 arene core. Correlation between the core structure and the aggregation properties-f-Susumu Arimori, Takeshi Nagasaki and Seiji Shinkai * Department of Chemical Science and Technology, Faculty of Engineering, Kyushu University, Fukuoka 812, Japan Water-soluble, conformationally-immobilized calixC4larenes (1 and 2,) with cone and 1,3-alternate conformations have been synthesized: at the para-position of each phenyl unit 1has a Me,N+CH, group and 2, has a Me,N+ [CH2],0CH2 group. Examinations with surface tension, fluorescence and dynamic light-scattering established that in water cone-1 aggregates into small micellar particles whereas such molecular aggregates are not detected for 1,3-alternate-l.In 2, both the cone and 1,3-alternate isomers formed aggregates in water but the cone isomers always gave CAC (critical aggregation concentration) values lower than the 1,3-alternate isomers. These results consistently indicate that the cone 2, isomers with a cone-shaped hydrophobic surface are more cohesive intermolecularly than the 1,3-alternate 2, isomers with a cylindrical hydrophobic surface. From the molecular shape one can expect that the cone isomers favourably form a globular micelle whereas the 1,3-alternate isomers favourably form a two-dimensional lamella. This was evidenced by the fact that 1,3-alternate-2, can form stable vesicular aggregates detectable by an electron microscope whereas cone-2, cannot form such stable aggregates.These results demonstrate that the aggregation properties of calixC4)arene-containing amphiphiles can be controlled by the conformational structure difference in the calixC4larene core. In aqueous solution, amphiphilic compounds tend to aggregate so that they can reduce the surface area contacting with the bulk water phase. The energy gain thus obtained is the origin of a hydrophobic force. ' The concept of the hydrophobic force suggests that if the hydrophobic surface shape of the monomer is different, the resultant aggregate formed in an aqueous medium may have a different three-dimensional architecture. Thus, the desired architecture may be tailor-made by skilfully designing the hydrophobic surface shape of the monomer as a building block.In the formation of synthetic bilayer mem- branes, for example, Kunitake et a1.2 demonstrated that the aggregation morphology can be partly regulated by the shape of the hard segment inserted into the central part of the amphiphile. For several years, we and others have been accumulating a basic knowledge about the syntheses of various calixC4larene conformer^.^-' It has been established that introduction of 0-substituents bulkier than an ethyl group (e.g.,propyl group) can inhibit the conformational isomerism which occurs via the oxygen-through-the-annulus rotation. 3,4 We here noticed that the surface shape of each conformer is quite different. If they aggregate in water so that they can reduce the surface area, their aggregation morphology should be also different.The idea has partly been realized by Regen et a1.'4T'5 and others'6.17 in a two-dimensional monolayer system. To the best of our knowledge, however, no precedent exists for the design of three- dimensional architectures from monomeric building blocks. Among calixC4larene conformers, the surface shape of the cone and 1,3-alternate is particularly different: cone-calixC41arene has a 'cone'-shaped surface which will aggregate into a globular micelle [as in Fig. 1 (a)] whereas 1,3-alternate-calix- [4]arene has a cylindrical surface 13,' ',19 which will aggregate into a two-dimensional lamella [as in Fig. l(b)]. To test this hypothesis, we synthesized water-soluble, conformationally- immobilized calix[4]arenes 1 and 2, (n = 4, 6 and 11) with a cone conformation or with a 1,3-alternate conformation.t Preliminary communication: S. Arimori, T. Nagasaki and S. Shinkai, J. Chem. Soc., Perkin Trans. I, 1993,887 (as a Perkin Communication). For synthetic simplicity cone-1 and 1,3-alternate-l carry C1- ion whereas cone-2, and 1,3-alternate-2, carry I-ion. Physical characterizations of these calix[4]arene-based amphiphiles have shown that in aqueous solution the cone isomers tend to aggregate more easily than the corresponding 1,3-alternate isomers and that only 173-alternate-2, can form stable vesicles detectable by an electron microscope. Results and discussion We first examined the aggregate formation of cone-1 and 1,3- alternate-1 by three independent methods.Surface tension (Wilhelmy method) of aqueous 1was measured in 'pure' water. As shown in Fig. 2, the surface tension for cone-1 abruptly decreased at ca. mol dm-3 whereas that for 1,3-alternate-1 was almost constant up to mol dm-3. In Fig. 3 we illustrate 1 2n (n =4, 6, 11) Cone 1,3-Altemate J. CHEM. SOC.PERKIN TRANS. 21995 7 Aggregation ~ ++ Cone +++++ +++++ ++ *O '1,3-Alternate Fig. 1 Expected aggregation modes of cone-shaped cone-1 (or 2,) (a)and cylindrical 1,3-alternate-l (or 2,) (b) Fig. 2 Surface tension us. concentration of 1 at 17 "C: (U) 1. alternate-1; (a)cone-1 the fluorescence intensity of a hydrophobic probe, 2-anilino- naphthalene in the presence of 1.It is seen from this Figure that in the presence of cone-1 the fluorescence intensity abruptly increases at 1.O x mol dm-3 whereas in the presence of 1,3-alternate-1 the fluorescence intensity remains constant. The light-scattering measurement of aqueous 1 established that cone-1 (0.010 mol dmP3) aggregates into particles with a 2040 8, diameter. Examination of CPK molecular models suggests that the length of the long axis of cone-1 is about 15 A and that of the short axis about 10 A. Thus, each particle should consist of several (probably, <ten) molecules. In contrast, we could not find any particle for 1,3-alternate-1 (0.010 mol dm-3) detectable by the light-scattering method. The fact that even a particle with a 20 A diameter cannot be found for 1,3-alternate-1 allows us to conclude that 1,3-alternate-l exists discretely as a monomer 0.5 I I I 1 I I 0.0 1.o 2.0 3.0 [Calixarene]/ 10-5 rnol dms Fig.Fluorescence intensity of 2-anilinonaphthalene (1 .OO x rnol dm-3)at 450 nm us. concentration of 1 :30 "C;excitation wavelength 3 15 nm; (U)and (a)as Fig. 2 even at 0.010 mol dmP3. We consider that the interaction among cylindrical hydrophobic surfaces of 1,3-alternate-1 is not strong enough to maintain the lamellar structure. The foregoing findings consistently support the view that the cone-shaped cone-1 forms micellar aggregates at around mol dm-3 whereas cylindrical 1,3-alternate-1 does not form such aggregates up to mol dm-3. The difference implies that the aggregation mode is well regulated by the surface shape of calixC4larene conformers.To facilitate the aggregation in water we introduced aliphatic chains between the calixC4larene and the four N'Me, groups. The last step in the synthesis of 2, is methylation of dimethylamino groups by methyl iodide. We attempted several methods to exchange I-in the products with Cl-- but to J. CHEM. SOC. PERKIN TRANS. 2 1995 70 -30t20-' ' t***l ' l*nngJ ' * ' J lo4 lo-' lo4 lo4 lo4 [Calixarene] / rnol dm4 Fig. 4 Surface tension us. concentration of 2, at 25 "C: (m) 1,3-alternate 2,; (a)cone 2, 80 70 r E 60 t +? \ .-% 50 u) c5 F'i8 40 't 3 cn 30 20 10~ lo4 10+ lo4 lo4 [Calixarene]/ rnol dm4 Fig.5 Surface tension us. concentration of 2, at 25 "C: (m) 1,3-alternate 2,; (a)cone 2, completely replace I-with C1-and to isolate the hygroscopic chloride salts was very difficult. Hence, we used the iodide salts for examination of the aggregation properties. Unfortunately, a fluorescence method cannot be applied to iodide-containing 2, because of the fluorescence quenching I-. We thus estimated their aggregation properties by surface tension and light scattering. The results are summarized in Figs. 4-6 and Tables 1 and 2. It is seen from Figs. 4-6 that in 2, both the cone and 1,3- alternate isomers form aggregates in water. The critical aggregate concentrations (CACs) become lower with increasing aliphatic chain length and the CAC values for the cone isomers are always lower than those for the corresponding 1,3-aIternate isomers (Table 1).Thus, the CAC for cone-%, (5.5 x mol dm-3) is lower by about four orders of magnitude than that for 1,3-alternate-2, (3.0 x rnol dmP3) and by about two orders of magnitude than that for 1,3-alternate-2, These results consistently indicate that the cone-2, isomers with a cone- shaped hydrophobic surface are more cohesive intermolecularly than the 1,3-alternate-2, isomers with a cylindrical hydrophobic surface. 681 Table 1 Critical aggregation concentrations (mol dm-3) of 1 and 2, determined by a surface tension method at 25 "C Conforma tion CalixC4larene Cone 1,3-Alternate 1" 1.0 x 10-5 -C lb 1.0 x 10-5 -C 24 5.0 10-5 3.0 x 10-3 26 1.0 x 10-5 1.0 10-3 211 5.5 x 10-7 3.0 x 10-5 17 "C.Determined by a fluorescence method using 2-amino-naphthalene at 30 "C. 'The CAC could not be detected. Table 2 Average particle sizes (A) of 1and 2, determined by a dynamic light-scattering method at 30 "C Particle size Calix[4]arene Cone 1,3-Alternate -b1 30 24 760 420 26 680 930 211 1150 1460 " 1.00 x lop2 mol dm-3 for 1,2, and 2,; 1.00 x 104mol dm-3 for 211. The aggregated particle could not be detected. 30'I-* 20 lo4 lo4 10-~ lo4 [Calixarene] / rnol dm4 Fig. 6 Surface tension us. concentration of 2,, at 25 "C: (m) 1,3-alternate 2, 1; (e)cone 2, The results of the light-scattering experiments are sum-marized in Table 2.In 2, we detected particles much larger than those for cone-1 ranging from 424 to 1464 A which change depending on the core structure and the aliphatic chain length. Careful examination of Table 2 reveals that in 2, the cone isomer aggregates into a particle larger than the 1,3-aIternate isomer whereas in 2, and 2,, the 1,3-alternate isomers aggre- gate into particles larger than the cone isomers. The inversion in the particle size implies that the aggregation mode of 2, is more or less similar to that of 1 whereas the aggregation mode of 2, and 2,, is somewhat different from that of 1. The working hypothesis of the present investigation is that inferring from their monomer shape, the cone isomer favourably forms a globular micelle whereas the 1,3-alternate isomer favourably forms a two-dimensional lamella.The two-dimensional lamella should have a molecular weight greater than the globular micelle but the maintenance of such gigantic aggregates should Fig. 7 Electron micrograph of 1,3-alternate-2,, vesicles; the sample solution was sonicated in the presence of uranyl acetate be energetically difficult unless the monomer has a sufficient hydrophobic surface. This situation is reflected by an inverse in the molecular weight: although the 1,3-alternate isomers of 1 and 2, have a cylindrical molecular shape, the hydrophobic surface is not wide enough to maintain the lamella structure, whereas those of 2, and 2,, are sufficiently hydrophobic and probably form lamellas with high molecular weights.To obtain further insights into the aggregation mode of 2, , we observed directly the aggregates by an electron microscope. This study was stimulated by electron-microscopic observations of bilayer membranes and bolaamphiphile membranes.2*20*21 Fig. 7 shows a TEM picture of the 1,3-alternate-2, ,aggregate. The sample was prepared by sonication of 2, ,in the presence of uranyl acetate. It is clearly seen from this picture that 1,3- alternate-2, forms vesicular aggregates with a 1000-2000 1$ diameter. The vesicular size is compatible with that determined by a light-scattering method (average particle 1460 A). The thickness of the lamella is ca. 100 A. Examination of CPK molecular models suggests that when the [CH,] , , chains in 2, , adopt an extended zigzag conformation, the length of the long axis is 44 A.We thus consider that the lamella consist of two layers but the resolution was not high enough to observe directly the two layers. In contrast, such a stable aggregate detectable by electron microscopy was not found for cone-2, ,. In addition, we carried out DSC studies of cone-2, , and 1,3- alternate-2, ,. 1,3-Alternate-2,, gave an exothermic peak (AH 120 kJ mol-') at 34 "C, indicating that 1,3-alternate-2,, forms oriented stable aggregates. For cone-2, ,,on the other hand, we could not observe such a DSC peak at 5-120 "C, suggesting that cone-2, , exists as thermodynamically stable aggregates like a globular micelle. Conclusions The present study demonstrates that the aggregation properties of amphiphiles are profoundly affected by the change in the molecular shape.In tetra-cationic amphiphiles with a calix- [4]arene core, the cone isomers are always more cohesive than the 1,3-aIternate isomers and 1,3-alternate-l cannot form as aggregate whereas 1,3-aIternate 2, ,can form stable vesicles. The difference in the aggregation properties is reasonably explained by the difference in the molecular shape: that is, the cone isomers have a cone shape which is favourable to the formation of a globular micelle and the 1,3-alternate isomers have a cylindrical shape which is favourable to the formation of a lamella. It is known that calix[4]arene conformers can be modified by various substituents3-'3.22-24 and some of them are useful as a 'core' in starburst dendrimer~.,~ We believe, therefore, that the basic skeleton of calixC41arene conformers is useful for the J. CHEM.SOC. PERKIN TRANS. 2 1995 design of a new surface shape, which will eventually lead to the regulation of the three-dimensional architecture of molecular assemblies. Experimental Preparation of cone-and 1,3-alternate-5,11,17,23-tetrakis-(chloromethyl)-25,26,27,28-tetrapropoxycalix[4]arene (cone-3 and 1,3-alternate-3, respectively) were described previously.26-29 Since the preparation methods for the cone and 1,3-alternate isomers are similar to each other, we here describe the preparation methods for the cone isomers and simply record the analytical data for the 1,3-aIternate isomers.5,11,17,23-Tetrakis(trimethyla1n1nonio1nethyl)-25,26,27,28-tetrapropoxycalix[4J arene tetrachloride (1) Cone-3 (500mg; 0.64mmol) was dissolved in dimethylformamide (DMF) (50 cm'). To this solution was introduced trimethyl- amine (gas) for 1 h at room temperature. The precipitate was collected by filtration, washed with chloroform and dried in uacuo. Cone-1: yield 37%, mp (decomp.) > 235 "C; dH[D20; 3-trimethylsilylpropanesulfonicacid, sodium salt (DSS) stan- dard; 25 "C; 250 MHz] 1.03 (12 H, t, CCH,), 2.01 (8 H, m, CH, in Pr), 2.91 [36 H, s, N(CH,),], 3.44 and 4.57 (4 H each, d each, ArCH,Ar), 4.01 (8H, t, OCH,), 4.23 (8H, s, NCH,) and 6.97 (8 H, s, ArH) (Found: C, 64.65; H, 8.1; N, 5.35. c56-H88C1,N404*H20 requires C, 64.59; H, 8.73; N, 5.38%). The treatment of 1,3-alternate-3 in a similar manner gave 1,3- alternate-1: yield 12%, mp (decomp.) > 269 "C; BH(D20; DSS standard; 25 "C; 250 MHz) 0.89 (12 H, t, CCH,), 1.56 (8H, m, CH, in Pr), 3.02 [36 H, s, N(CH,),], 3.72 (8 H, t, OCH,), 3.95 (8 H, s, NCH,), 4.35 (8H, s, ArCH,Ar) and 7.36 (8H, s, ArH) (Found: C, 63.9; H, 8.4; N, 5.2.C,6H88C14N404e2H20 requires C, 63.49; H, 8.77; N, 5.29%). The water content in these samples has been confirmed by a Karl-Fischer titration. 5,11,17,23-Tetrakis(trhethylammoniobutyloxymethy1)-25,26,-27,28-tetrapropoxycalix[4]arene tetraiodide (2,) N,N-Dimethylaminobutan-1-ol(0.85 cm3; 5.12 mmol) and potassium tert-butoxide (690 mg; 6.14 mmol) were dispersed into THF (20 cm3) and the mixture was stirred for 30 min at room temperature.Cone-3 (500 mg; 0.64 mmol) was added and then the reaction mixture was refluxed for one day under a nitrogen stream. After cooling, the mixture was diluted with aqueous 5% NaHCO, solution (100 cm'). After cooling in an ice-bath, the organic layer was separated, washed with NaC1- saturated water and dried over MgS04. The concentration of this solution in uacuo resulted in a yellow oil. The product was used without further purification for quaternization with methyl iodide (2.0 cm3; 6.18 mmol) in DMF (20 cm3) at room temperature for 12 h. The solution was concentrated in uacuu to dryness, the residue being purified by column chromatography (Sephadex LH-20, methanol).Cone-2,: yield 74%, mp 146- 149 "C; &(CD@D; Me4%; 25 "C; 250 MHz) 1.03 (12 H, t, CCH,), 1.64 (8H, m, CH, in Pr), 1.93 (16 H, m, OC[CH,],), 3.17 [36 H, s, N(CH,),], 3.39 (8 H, t, NCH,), 3.44 (8 H, t, OCH,) 3.55 and 4.49 (4 H each, d each, ArCH,Ar), 3.86 (8 H, t, OCH, in Pr) and 4.19 (8 H, s, ArCH,), 6.67 (8 H, s, ArH) (Found: C, 53.5; H, 7.2; N, 3.0. C,2H12014N408~1.2C6H14 requires C, 53.05; H, 7.63; N, 3.13%). The treatment of 1,3- alternate-3 in a similar manner gave 1,3-alternate-2,: yield 62%, mp (decomp.) > 245 "C; dH(CD30D; Me4Si; 25 "C; 250 MHz) 0.90 (12 H, t, CCH,), 1.54 (8 H, m, CH, in Pr), 1.72 (8H, m, CH,CN), 1.85 (8H, m, OCCH,), 3.15 [36 H, s, N(CH,),], 3.41 (8 H, t NCH,), 3.49 (8 H, t, OCH,), 3.55 (8H, t, OCH, in Pr), 3.68 (8H, s, ArCH,Ar), 4.35 (8H, s, ArCH,) and 7.01 (8H, s, ArH) (Found: C, 51.8; H, 7.15; N, 3.1.C72H12014N408 requires C, 51.55; H, 7.22; N, 3.34%). J. CHEM. SOC. PERKIN TRANS. 2 1995 5,11,17,23-Tetrakis(trimethylammoniohexyloxymet hyl)-25,26,-27,28-tetrapropoxycalix[41arene tetraiodide (2d Cone-2, was synthesized by the reaction of cone-3 and N,N-dimethylaminohexan- 1-01 followed by quaterization with methyl iodide in a manner similar to that described for 2,: yield 67%, mp 132-1 35 "C; 6,(CD30D; Me,% standard; 25 "C; 250 MHz) 1.03 (12 H, t, CCH,), 1.46 (16 H, m, OCC[CH,],), 1.60 (8 H, m, CH, in Pr), 1.81 (8 H, m, OCCH,), 1.99 (8 H, m, NCCH,), 3.14 [36 H, s, N(CH,),], 3.34 (8 H, t, NCH,), 3.38 (8 H, t, OCH,), 3.40 and 4.49 (4 H each, d each, ArCH,Ar), 3.86 (8 H, t, OCH, in Pr), 4.14 (8 H, s, ArCH,) and 6.74 (8 H, s, ArH) (Found: C, 54.4; H, 7.63; N, 2.9.c8oH13614- N408*0.7C6H,, requires c, 53.31; H, 7.91; N, 3.01%). The treatment of 1,3-alternate-3 in a similar manner gave 1,3- alternate-2,: yield 74%, mp 125-128 "C; d,(CD,OD, Me,% standard; 25 "C; 250 MHz) 0.91 (12 H, t, CCH,), 1.45 (16 H, m, OCC[CH,],), 1.50 (8 H, t, CH, in Pr), 1.62 (8 H, m, OCCH,), 1.80 (8 H, m, NCCH,), 3.07 [36 H, s, N(CH,),], 3.50 (8 H, t, NCH,), 3.39 (8 H, t, OCH,), 3.48 (8 H, t, OCH, in Pr), 3.66 (8 H, s, ArCH,Ar), 4.32 (8 H, s, ArCH,) and 6.99 (8 H, s, ArH) (Found: C, 53.8; H, 7.6; N, 3.0. C80H13,1,N,08 requires C, 53.69: H, 7.68; N, 3.13%). 5,11,17,23-Tetrakis(trimethylamonioundecycloxymethy1)-25,26,27,28-tetrapropoxycalix[4]arene tetraiodide (2, Cone-2,, was synthesized by the reaction of cone-3 and N,N-dimethylaminoundecan- 1-01 followed by quaterization with methyl iodide in a similar manner to that described for 2,: yield 43%, mp 145-148 "C; G,(CD,OD; Me,Si standard; 25 "C; 250 MHz) 1.01 (12 H, t, CCH,), 1.30 (56 H, m, OCC[CH,J,), 1.53 (16 H, m, CH, in Pr, NCCH,), I .77 (8 H, m, OCCH,), 3.13 [36 H, s, N(CH,),], 3.28 (8 H, t, NCH,), 3.33 (8 H, t, OCH,), 3.45 and 4.48 (4 H each, d each, ArCH,Ar), 3.84 (8 H, t, OCH, in Pr), 4.13 (8 H, s, ArCH,), 6.72 (8 H, s, ArH) (Found: C, 57.5; H, 8.8; N, 2.35.C,ooH,,,14N,08~CH30H requires C, 57.70; H, 8.65; N, 2.67%). The treatment of 1,3-alternate-3 in a similar manner gave 1,3-alternate-2, : yield 34%, mp 93-95 "C; G,(CD,OD; Me4Si standard; 25 "C; 250 MHz) 0.96 (12 H, t, CCH,), 1.33 (56 H, m, OCC[CH,],), 1.50-1.70 (24 H, m, CH, in Pr, NCCH,, OCCH,), 3.30 [36 H, S, N(CH,)J, 3.40 (8 H, t, NCH,), 3.38 (8 H, t, NCH,), 3.43 (8 H, t, OCH,), 3.46 (8 H, t, OCH, in Pr), 3.63 (8 H, s, ArCH,Ar), 4.31 (8 H, s, ArCH,) and 6.98 (8 H, s, ArH) (Found: c, 57.4; H, 8.8; N, 2.2.ClooH17,14N408~ 1.8CH3OH requires C, 57.45; H, 8.69; N, 2.63%). Estimation of aggregation properties Surface tension was estimated by a Wilhelmy method using a Kyowa ESB-IV apparatus. The detail of the method was described previously. 30 The light-scattering measurements were carried out on an Otsuka Electronics DLS-700 apparatus, The fluorescence measurements were carried out on a Hitachi 650- 10s spectrophotometer.Electron microscopy (Hitachi H-500 electron microscope) was used for the observation of the aggregates formed from cone- and 1,3-alternate-2, 1. 2, ,(1.35 mg; 0.65 mmol) was dispersed into aq 2% uranyl acetate solu- tion (2 cm3) and the mixture was sonicated with a Branson Sonifer (Model 185) for 2 min at room temperature. The sample was prepared according to the method reported by Kunitake and Okahata.,' The DSC measurements were carried out on a Seiko SSC/5200 Calorimeter. The concentrations of the aqueous sample solutions were 10-45 mmol dmP3 for cone-2 , and 1 .O mmol dm-, for 1,3-alternate-2, ,. References 1 C. Tanford, The Hydrophobic ESfect, Wiley, New York, 1973.2 T. Kunitake, Y. Okahata, M. Shimomura, S. Yasunami and K. Takarabe, J. Am. Chem. 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SOC.,1991,113,2385. 13 W. Verboom, S. Datta, Z. Asfari, S. Harkema and D. N. Reinhoudt, J. Org. Chem., 1992,57, 5394. 14 M. A. Markowitz, R. Bielski and S. L. Regen, Langmuir, 1989,5,276. 15 M. Conner, V. Janout and S. L. Regen, J. Am. Chem. Soc., 1993,115, 1178. 16 Y. Ishikawa, T. Kunitake, T. Matsuda, T. Otsuka and S. Shinkai, J. Chem. SOC.,Chem. Commun., 1989,736. 17 Y. Nakamoto, G. Kallinowski, V.Bohmer and W. Vogt, Langmuir, 1989,5, 11 16. 18 J. L. Atwood and S. G. Bott, Top. Inclusion Soc., 1991, 3, 199 and refs. cited therein. 19 K. Fujimoto, N. Nishiyama, H. Tsuzuki and S. Shinkai, J. Chem. SOC.,Perkin Trans. 2, 1992,643. 20 T. Kunitake and Y. Okahata, J. Am. Chem. Soc., 1977,99,3860. 21 J. H. Fuhrhop and D. Fritsch, Acc. Chem. Res., 1986,19, 130. 22 C. D. Gutsche, Culixarenes, Royal Society of Chemistry, Cambridge, 1989. 23 J.-D. van Loon, A. Arduini, L. Coppi, W. Verboom, A. Pochini, R. Ungaro, S. Harkema and D. N. Reinhoudt, J. Org. Chem., 1990, 55, 5639. 24 S. Shinkai, H. Kawabata, T. Matsuda, H. Kawaguchi and 0.Manabe, Bull. Chem. Soc. Jpn., 1990,63, 1272. 25 G. R. Newkome, Y. Hu, M. J. Saunders and F. R. Fronczek, Tetrahedron Lett., 1991,32, 1133. 26 A. Ikeda, T. Nagasaki, K. Araki and S. Shinkai, Tetrahedron, 1992, 48, 1059. 27 T. Nagasaki, K. Sisido, T. Arimura and S. Shinkai, Tetruhedron, 1992,48,797. 28 A. Ikeda and S. Shinkai, J. Chem. Soc., Perkin Trans. I, 1993,2671. 29 A. Ikeda and S. Shinkai, J. Am. Chem. SOC.,1994,116,3102. 30 S. Shinkai, S. Mori, H. Koreishi, T. Tsubaki and 0. Manabe, J. Am. Chem. Soc., 1986,108,2409. 31 T. KunitakeandY. Okahata, J. Am. Chem. SOC.,1980,102,549. Paper 4/04650A Received 29th July 1994 Accepted 7th December 1994

ISSN:1472-779X    

DOI:10.1039/P29950000679

出版商:RSC    

年代:1995

数据来源: RSC