Biomacromolecules 2005, 6, 1707-1712
1707
Asymmetric Epoxidation of r-Olefins Having Neighboring Sugar Chiral Templates and Alternating Copolymerization with Dicarboxylic Anhydrides Akinori Takasu,* Takashi Bando, Yusuke Morimoto, Yosuke Shibata, and Tadamichi Hirabayashi Department of Environmental Technology and Urban Planning, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan Received December 25, 2004; Revised Manuscript Received February 9, 2005
Sugar-substituted epoxides 5-8 were synthesized by asymmetric epoxidation (in CH2Cl2/water) of R-olefins having neighboring sugars (1-4) by use of an achiral oxidant (MCPBA), in which the sugar moiety acted as a chiral template. The diastereoselectivities depend on the methylene spacer between vinyl group and carbohydrate derivatives. The methylene spacer between sugar and vinyl groups influenced the diastereoselectvity. In the case of epoxidation of 4 at 27 °C for 24 h, the diastereoselectivity was the highest (99/1). Copolymerizations of 5-8 with succinic anhydride were attained at 100 °C for 72 h to give poly(ethylene succinate) having pendant carbohydrate [poly(SAn-alt-5), Mn ) 1.4 × 103; poly(SAn-alt-6), Mn ) 2.2 × 103; poly(SAn-alt-7), Mn ) 2.9 × 103; poly(SAn-alt-8), Mn ) 1.8 × 103]. The methylene spacer between sugar and epoxide has an effect on the reactivity of epoxide in copolymerization as well as the diastereoselectivity. Alternating copolymerization of 7 and glutaric anhydride gave a polyester of Mn 4.2 × 103. Introduction Poly(alkylene succinate)s including poly(ethylene succinate) (PES) and poly(butylene succinate) (PBS) are some of the most important biodegradable polyesters, which may replace many conventional plastics soon because of their acceptable mechanical strength and comparable softening temperature to low-density polyethylene and polystyrene.1 In general, chemosynthesis is attained by polycondensation of aliphatic dicarboxylic acid and diol compounds at 200250 °C under highly reduced pressure.2 As another route, ring-opening alternating copolymerization of oxirane and succinic anhydride (SAn) is an interesting approach.3 Controlled synthesis of PES (Mn > 1.0 × 104) has already been reported with magnesium diethoxide [Mg(OEt)2] as the catalyst.3c We also reported synthesis of biodegradable polyesters by ring-opening alternating copolymerization of oxiranes with unsaturated cyclic anhydrides including itaconic and citraconic anhydrides to give polyesters having exo- and endo-type double bonds, respectively.4 Incorporation of an unsaturated unit into polyester is effective for chemical modification,5 cross-linking,4 and control of biodegradation rate.6 From the environmental viewpoint, greater attention has been directed to effective utilization of carbohydrate biomass as an alternative, renewable resource that can be steadily supplied and used for polymer synthesis.7 Recently, we reported direct O-glycosidation of hydroxyl groups in * To whom correspondence should be addressed: e-mail takasu.akinori@ nitech.ac.jp.
poly(vinyl alcohol) (PVA)8a and the accelerated biodegradation.8b,c Therefore, we can expect that introduction of a carbohydrate unit as well as an unsaturated unit into aliphatic polyester would influence the biodegradation rate. In this paper, we report asymmetric epoxidations of alkenes having a methylene spacer and pendant acetylated sugar as a chiral template, using m-chloroperbenzoic acid (MCPBA) and Lewis acid-catalyzed alternating copolymerization with dicarboxylic anhydrides to give PES having pendant sugar. Although Charette and Cote9 reported that an epoxidation of 1-O-butenyl-3,4,6-tri-O-benzyl-β-D-glucopyranose gave a 9:1 mixture of diastereomers, this is the first example of polymerization behavior of sugar-substituted epoxides. If the chiral epoxides are opened β-selectively by use of a bulky aluminum Lewis acid, stereoregular (isotactic) biodegradable polyesters would be obtained (Scheme 1). The tacticity would affect the biodegradation. To our best knowledge, reports on regioselectivity (iso/syndioregic orientation) in the alternating copolymerization of succinic anhydride and oxiranes have not been published. Therefore, we also investigated the regioselectivity in this study. Experimental Section Materials. Methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD), triethylamine, allyl alcohol, 3-butenol, 4-pentenol, epoxybutane (EB), glutaric anhydride (GAn), and styrene oxide (SO) were purchased from Tokyo Kasei Co. (Tokyo, Japan). m-Chloroperbenzoic acid (MCPBA), silver trifluoromethanesulfonate (AgOTf), SAn, aluminum triisopropoxide [Al(OiPr)3], propylene oxide (PO), and 1-methoxy2-propanol were obtained from Nacalai Tesque (Kyoto,
10.1021/bm0491826 CCC: $30.25 © 2005 American Chemical Society Published on Web 03/17/2005
1708
Biomacromolecules, Vol. 6, No. 3, 2005
Takasu et al.
Scheme 1. Alternating Copolymerization of Sugar-Substituted Chiral Epoxide with SAn to Afford Isotactic PES Having Pendant Sugar
Japan). Mg(OEt)2 was purchased from Wako Pure Chemical (Osaka, Japan). Methylaluminum bis(2,6-di-tert-butyl-4bromophenoxide) (MABR) and 2-methoxypropanol were prepared in our laboratory. Chloroform, dichloromethane, benzonitrile, diethyl ether, and water used were purified by distillation before use. Measurements. Fourier transform infrared (FT IR) spectra were recorded for KBr disks on a Jasco FT/IR-430 spectrometer. 1H and 13C NMR spectra were measured at 27 °C on a Bruker DPX200 spectrometer (200 MHz for 1H NMR). All chemical shifts were expressed as δ downfield from tetramethylsilane (TMS). Number-average molecular weights (Mn) and polydispersity indexes (Mw/Mn) of polymers were estimated by size-exclusion chromatography (SEC) calibrated with polystyrene standards on a pump system of Tosoh DP8020 with a refractive index (Tosoh RI-8020) detector and Tosoh G2000, 3000, 4000, and 5000-HXL columns (eluent, THF; flow rate, 1.0 mL/min; temperature, 40 °C). High-performance liquid chromatography (HPLC) measurements with a chiral stationary phase (Daicel Chiralcel ODH) were performed by a Tosoh CCPE pump equipped with UV (Tosoh UV8020) detector [eluent, n-hexane/2-propanol (8/2 v/v)]. Preparation of Sugar-Containing Alkene. For 2-propenyl 2-acetamido-2-deoxy-β-D-glucopyranoside (1): In a flask, 5.5 g (15.0 mmol) of 2-acetamido-3,4,6-triacetyl-RD-glucopyranosyl chloride10 (15.0 mmol) and 1.5 mL (30.0 mmol) of allyl alcohol was dissolved in 65 mL of dichloromethane. Under nitrogen, 5.8 g (22.6 mmol) of AgOTf was added into the solution at 0 °C and stirred for 20 min. At 40 °C, the reaction mixture was kept for 24 h and the reaction was terminated by adding triethylamine (1.9 mL, 24.9 mmol) and diluted by 195 mL of dichloromethane. AgOTf was removed by filtration and the filtrate was washed with
saturated aqueous NaHCO3 and water and dried with MgSO4. The organic layer was concentrated and recrystallized from ethanol to afford white solid (3.8 g, 40% yield). 1H NMR δ (CDCl3) 1.95 (s, 3H, NHCOCH3), 2.02, 2.03, 2.08 (3s, 9H, OCOCH3), 3.65-3.73 (m, 1H, H-5), 3.88 (dd, 1H, J ) 9.0 and 10.0 Hz, H-2), 4.17-4.35 (4H, H-6a,6b and sugar-OCH2CHdCH2), 4.71 (d, 1H, J ) 8.3 Hz, H-1β), 5.07 (t, 1H, J ) 10.0 Hz, H-4), 5.22-5.34 (m, 3H, J ) 10.0 Hz, H-3 and sugar OCH2CHdCH2), 5.61 (d, 1H, J ) 8.0 Hz, NHCOCH3), 5.77-5.96 (m, 1H, sugar OCH2CHdCH2). Asymmetric Epoxidation of Alkenes Having Pendent Sugar. For 2,3-epoxypropyl 2-acetamido-3,4,6-tri-O-acetylβ-D-glucopyranoside (5): MCPBA (1.2 g, 6.7 mmol) was slowly added in small portions to a stirred mixture of 1 (1.4 g, 3.7 mmol) in dichloromethane (37 mL) and 0.5 M aqueous NaHCO3 (11 mL). The mixture was stirred at room temperature for 24 h. After the reaction, the organic phase was separated, and 2-propanol was added in order to terminate. Successively, the solution was washed with water and dried over MgSO4, and triethylamine was added in order to neutralize. Dichloromethane was removed under reduced pressure to yield syrupy yellow product (43% yield, run 1 in Table 1). 1H NMR δ (CDCl3) 1.95 (s, 3H, NHCOCH3), 2.02, 2.03, 2.08 (3s, 9H, OCOCH3), 2.52-2.79 (m, 2H, sugar OCH2CHCH2), 3.10-3.20 (m, 1H, sugar OCH2CHCH2), 3.58-3.73 (m, 1H, H-5), 3.90-4.30 (5H, H-2,6a,6b and sugar OCH2CHCH2), 4.64, 4.75 (2d, 1H, J ) 8.4 Hz, H-1β), 5.07 (t, 1H, J ) 9.0 Hz, H-4), 5.25 (t, 1H, J ) 10.0 Hz, H-3), 5.64 (d, 1H, J ) 10.0 Hz, NHCOCH3). Alternating Copolymerization of 6 with Succinic Anhydride by MAD. To a test tube containing a solution of 6 (33 mg, 0.33 mmol), SAn (33 mg, 0.33 mmol), and benzonitrile (0.2 mL) in a nitrogen atmosphere was added 0.16 mL of 0.4 M MAD toluene solution (0.64 mmol). The
Asymmetric Epoxidation of R-Olefins
Biomacromolecules, Vol. 6, No. 3, 2005 1709
Scheme 2. Asymmetric Epoxidation of Olefin Having a Sugar Template and Subsequent Alternating Copolymerization with SAn
Table 1. Diastereoselective Epoxidationa of Olefins Having Neighboring Sugars by MCPBAb sugar-substituted epoxide diastereoselectivity entry
olefins (mmol)
temp (°C)
1 2 3 4 5 6 7 8
1 (3.70) 1 (3.36) 1 (3.36) 2 (3.70) 2 (3.24) 3 (0.87) 3 (0.87) 4 (0.87)
27 10 0 27 10 27 10 27
conversionc (%)
yield (%)
by 1H NMRc
by HPLCd
>99 >99 75 >99 >99 >99 >99 >99
43 56 56 76 69 48 62 85
73/27 81/19 83/17 63/37 65/35 58/42 58/42
75/25
5 5 5 6 6 7 7 8
85/15 70/30
99/1
a In dichloromethane/water, [olefin] ) 0.1 M in dichloromethane, [MCPBA] /[olefin] ) 1.8, for 24 h. b m-Chloroperbenzoic acid. c Determined by 1H 0 0 0 NMR spectrum in CDCl3. d Determined by HPLC [column, Chiralcel OD-H; eluent, hexane/2-propanol (8/2 v/v)].
exhausting-refilling process was repeated three times, and then the tube was sealed and put into an oil bath at 100 °C with vigorous stirring for 72 h. The reaction mixture was diluted with chloroform and poured into an excess of diethyl ether to precipitate out the product. The purified polymer was dried under reduced pressure until constant weight (46% yield, run 11). 1H NMR (200 MHz, CDCl3, δ, ppm): 1.94 (s, 3H, NHCOCH3), 2.02, 2.04, 2.08 (3s, 9H, OCOCH3), 2.39-2.83 (4H, COCH2), 3.53-3.61 (1H, H-5), 3.64-3.80 (1H, H-2), 3.98-4.32 (8H, H-6a,6b, sugar OCH2CH2, and CH2CH), 4.50 (br d, 1H, J ) 8.5 Hz, H-1β), 4.91-5.48 (4H, H-3,4, sugar OCH2CH2CH, and NHCOCH3). IR (KBr disk, cm-1): 2958 (νC-H), 1741 [νCdO(ester)], 1372 (δC-H), 1233 [νC-O(ester)]. Results and Discussion Epoxidations of alkenes having pendant sugars were carried out in a simple and mild bilayer (dichloromethane/ water) system, which is superior to the single solvent method for epoxidation of acid-sensitive olefins containing ester,
acetal, and hemiacetal linkages.11 The procedure is outlined in Scheme 2, and the results are summarized in Table 1. First, 2-propenyl 3,4,6-tri-O-acetyl-2-deoxy-2-acetamido-βD-glucopyranoside (1) containing ester and acetal linkages was epoxidized by MCPBA at 27 °C for 24 h (run 1). H-1 proton (at 4.71 ppm) of precursor 1 disappeared, indicating that complete epoxidation occurred. Suprisingly, new two anomeric protons appeared in the 1H NMR spectra of N-acetyl-D-glucosamine- (GlcNAc-) substituted epoxide 5 [at 4.64 (d, J12 ) 8.4 Hz) and 4.75 (d, J12 ) 8.4 Hz) ppm, Figure 1] in CDCl3 solvent. The ratio was 73/27 (Table 1, run 1). In HPLC measurements with a chiral stationary phase [column, Chiralcel OD-H (Daicel); eluent, hexane/2-propanol ) 8/2], two distinct signals were observed and the peak ratio was 75/25 (Figure 2). The ratio did not contradict the 1H NMR results. These results apparently indicated that sugarderivative-directed asymmetric epoxidation was induced by achiral oxidant (MCPBA). At lower temperature (10 °C), the ratio of diastereomers increased to 81/19 (Table 1, run 2). In the case of epoxidation of 1 at 0 °C for 24 h, higher diastereoselectivity (83/17) was attained. Next, we tried to
1710
Biomacromolecules, Vol. 6, No. 3, 2005
Figure 1. Expanded 1H NMR spectrum of sugar-substituted epoxide 5 in CDCl3 (27 °C, 200 MHz).
Figure 2. HPLC measurement of sugar-substituted epoxides 5 (top, run 1 in Table 1), 6 (middle, run 4 in Table 1), and 8 (bottom, run 8 in Table 1) with a chiral stationary phase [column, Chiralcel OD-H (Daicel); eluent, n-hexane/2-propanol (8/2 v/v); flow rate, 0.4 mL/min; temperature, 25 °C].
epoxidize 3-butenyl β-D-GlcNAc(Ac)3 (2), 4-pentenyl β-DGlcNAc(Ac)3 (3), and 10-undecenyl β-D-GlcNAc(Ac)3 (4) by the same procedure. In the case of 6 as well as 5, two anomeric protons were observed at 4.62 and 4.69 ppm (diastereoselectivity 63/37), and the chemical shift difference (∆ν) was lower (0.07 ppm) than that of 5 (0.11 ppm). The assignment of 1H NMR spectrum was confirmed by 1H-1H COSY NMR measurements, in which the two H-1 signals of 6 correlated with H-2 protons of the sugar moiety (Supporting Information). Neither temperature (64/36 at 40 °C) nor solvent (64/36 in CD3CN) in the measurement affected the relative intensity in the 1H NMR spectrum. The diastereoselectivities of 6 (n ) 2) and 7 (n ) 3) at 27 °C were 63/37 and 58/42, respectively (Table 1, runs 4 and 6). The selectivities were lower than that of 5. Surprisingly, the diastereoselectivity of 8 (n ) 9) from HPLC measurement was the highest (99/1) as shown in Figure 2, in which conformation of sugar-containing alkene 4 seems to affect
Takasu et al.
the asymmetric epoxidation. We revealed that the length of the spacer between chiral template and alkene influenced the diastereoselectivity. In this study, we found that a bulky aluminum Lewis acid, methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD), as well as Mg(OEt)2 catalyzed alternating copolymerization of SAn with propylene oxide (PO), epoxybutane (EB), and styrene oxide (SO) in which the oxirane opened β-preferentially.12 Although Aida and Inoue13 also reported MAD-catalyzed alternating copolymerization of phthalic anhydride and ethylene oxide with porphyrin as an initiator, this system does not need the expensive porphyrin initiator. Moreover, both the yield and Mn were superior to those of the polyester synthesized with Mg(OEt)2 as the catalyst (runs 1 and 4 in Table 2). In the 1H NMR spectrum, a singlet peak (at 1.39 ppm) assigned to tert-butyl substituent on phenoxide was observed, showing that 2,6-di-tert-butyl-4-methylphenoxide initiated the alternating copolymerization. The microstructure (isoregic/syndioregic orientation) was evaluated by 13 C NMR measurements in comparison with the resonance pattern of iso- and syndioregic model compounds (see Supporting Information). While the isoregic model compound composed of SAn, 1-methoxy-2-propanol, and 2-methoxypropanol showed two methylene carbons (ascribed to SAn unit) at 28.9 and 29.2 ppm, singlet signals at 29.3 and 28.8 ppm were observed in syndioregic (head-to-head and tailto-tail) models. The syndioregic model compounds were prepared from SAn with 2 equiv of 1-methoxy-2-propanol and 2-methoxypropanol, respectively. Expectedly, methylene carbon (COCH2CH2CO) split into four peaks (28.7, 28.8, 29.0, and 29.1 ppm) in the 13C NMR spectra of poly(SAnalt-PO)s (runs 1-3 in Table 2). We could determine that two of them (at 28.8 and 29.0 ppm) are ascribed to isoregic structure and the others are due to syndioregic one (Supporting Information). The regioselectivities in MADcatalyzed alternating copolymerization of SAn with PO and EB were calculated to be 58/42 and 69/31, respectively. On the other hand, the regioselectivities (iso/syndio) of alternating copolymerization of SAn with PO (47/53) and EB (63/ 37) by Mg(OEt)2 were lower than those by MAD. In the alternating copolymerization of bulky epoxide, SO, higher isoregicity was obtained (85/15, run 6 in Table 2). These results indicated that MAD-catalyzed alternating copolymerization proceeds via β-preferential ring opening of the epoxide and that bulkiness of R-substituents as well as the catalyst is effective for regioselective alternating copolymerization of SAn with monosubstituted epoxide. For much bulkier sugar-substituted propylene, butylene, pentene, and undecene oxides (5-8), it is expected that regioselective ring-opening alternating copolymerization would occur to afford isotactic-rich PES having pendant carbohydrate. The copolymerizations were carried out in benzonitrile at 100 °C for 72 h. The structure was confirmed by IR and 1H NMR analyses. In the 1H NMR spectrum of poly(5-co-SAn), we could not observed any peak due to homosequence of the epoxide (around 3.5 ppm), and the unit ratio of SAn and the sugar-substituted epoxide calculated from the peak intensity ratio at 2.39-2.83 ppm (COCH2 in SAn unit) and 1.94-2.08 ppm (COCH3 in sugar-substituted
Asymmetric Epoxidation of R-Olefins
Biomacromolecules, Vol. 6, No. 3, 2005 1711
Table 2. Alternating Copolymerization of Sugar-Substituted Epoxide with Dicarboxylic Anhydridesa epoxide entry
mmol
diastereoselectivityb
cyclic anhydride
catalyst
yield (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
PO (14.3) PO (14.3) PO (14.3) EB (14.3) EB (14.3) SO (14.3) 5 (1.41) 5 (1.44) 6 (1.20) 6 (0.28) 6 (0.33) 7 (0.52) 7 (0.42) 8 (0.52) 8 (0.42)
50/50 50/50 50/50 50/50 50/50 50/50 73/27 73/27 63/37 58/42 63/37 58/42 58/42 99/1 99/1
SAn SAn SAn SAn SAn SAn SAn SAn SAn SAn SAn SAn GAn SAn GAn
Mg(OEt)2 MAD MABR Mg(OEt)2 MAD MAD MAD MABR Mg(OEt)2 Al(OiPr)3 MAD MAD MAD MAD MAD
28 55 78e 55 81 31 19 31 40 39 46 17 26 39 34
Mn × 10-3 (Mw/Mn) 1H NMRb SECc 4.5 (1.30) 7.8 (1.23) 8.1 (1.18) 3.2 (1.31) 6.0 (1.27) 3.7 (1.17) 1.4 (1.05) 0.97 (1.25) 0.67 (1.19) 1.5 (1.22 ) 2.2 (1.12 ) 2.9 (1.18 ) 4.2 (1.11 ) 1.8 (1.33 ) 1.7 (1.7)
4.4 13.7
2.3
[epoxide]/ [SAn]b
[iso]/ [syndio]d
46/54 48/52 49/51 49/51 49/51 50/50 50/50 50/50 50/50 50/50 50/50 50/50 50/50 50/50 50/50
47/53 58/42 57/43 63/37 69/31 85/15
a In toluene (runs 1-6) and benzonitrile (runs 7-15); [epoxide + SAn] ) 9.5 M (runs 1-6) and 3.0 M (runs 7-13); [epoxide + SAn] /[catalyst] ) 250 0 0 0 (runs 1-6) and 100 (runs 7-15); [epoxide]0/[dicarboxylic anhydride]0 ) 50/50; time, 72 h; temp, 100 °C. b Determined by 1H NMR spectrum in CDCl3. c Determined by SEC measurement in THF relative to polystyrene. d Ratio of isoregic and syndioregic structure in the polyester, determined by 13C NMR spectra in CDCl3. e For 24 h.
epoxide) was 50/50. From these results, it was revealed that MAD-catalyzed alternating copolymerization of SAn and 5 occurred to give PES having pendant GlcNAc (run 7 in Table 2). MABR14 as well as MAD15 is known to be an excellent bulky aluminum Lewis acid for some organic reactions. Although MABR was a better catalyst for alternating copolymerization of PO with SAn (run 3), it was not effective for 5 (run 8). Copolymerization of 5 and SAn was attained at 100 °C for 72 h to give PES having pendant carbohydrate [46% yield, Mn ) 2.2 × 103 (SEC), run 11]. The Mn is higher than that from Mg(OEt)2 system (Mn ) 0.7 × 103, run 9). In the Mg(OEt)2 system, we could calculate the Mn from the 1H NMR intensity ratio of -CH2CH2- (2.39-2.83 ppm) and R-terminal OCH2CH3 group (1.41 ppm).3c The Mn from NMR was ca. 3 times higher than that from SEC and we can expect that Mn values from SEC are underestimated. The methylene spacer influenced the polymerizability. MADcatalyzed alternating copolymerization of sugar-substituted epoxide having a longer methylene spacer, 6, affords a sugarcontaining PES with Mn (SEC) of 2.9 × 103 (17% yield, run 12). Moreover, alternating copolymerization of 6 and glutaric anhydride (GAn) gave a polyester with much higher Mn (SEC) of 4.2 × 103 (run 12), because steric hindrance between the pendant carbohydrate derivatives was suppressed. In the expanded 13C NMR spectra of the alternating polymers composed of SAn and GlcNAc-substituted epoxides 5-7, broad methylene carbons due to the SAn unit were observed around 28-30 ppm and did not enable us to qualify the regioselectivities (Supporting Information). However the signals of poly(5-alt-SAn) and poly(6-alt-SAn) are unimodal, supporting that the polyesters have predominantly isoregic structures with ring opening of epoxides by attack at β selectively. From the results of copolymerization of SAn with PO, EB, and SO, it is reasonable that the sugarcontaining polyesters have an isoregic orientation predominantly. The regioselectivities and influence on the biodegradability will be discussed in our forthcoming paper. In the present paper, we describe asymmetric epoxidation of vinyl sugar by achiral oxidant in which the carbohydrate
moiety acts as an chiral auxiliary.9 The asymmetric epoxidation made it possible to synthesize isotactic-rich aliphatic polyesters having pendant sugar via regioselective alternating copolymerization catalyzed by bulky aluminum Lewis acid. These fundamental results show promise for advanced molecular and material design with carbohydrate as a sustainable resource alternative to oil, which is classified as a “Green Polymer Chemistry” concept.2e-g,16 Acknowledgment. This work was funded by the Ministry of Education, Science and Culture of Japan (Grant-in-Aid for Development Scientific Research, 16750095). Additional support came from Japan Science and Technology Agency (JST) and Nagoya Institute of Technology, research promotion program. We also acknowledge Dr. Shigenobu Takenouchi and Mr. Kazuhiro Iso (Nagoya Institute of Technology) for their technical help and fruitful discussion. Supporting Information Available. 1H-1H COSY NMR spectrum of 6, 13C NMR data for iso- and syndioregic model compounds (1:2 adducts), and expanded 13C NMR spectra of poly(5-alt-SAn), poly(6-alt-SAn), and poly(7-alt-SAn). These materials are available free of charge via the Internet at http://pubs.acs.org. References and Notes (1) (a) Lenz, R. W. AdV. Polym. Sci. 1993, 107, 1. (b) Koeshak, V. V.; Vinogradora, S. V. Polyester; Pergamon Press: New York, 1995. (2) (a) Carothers, W. H.; Dorough, G. L. J. Am. Chem. Soc. 1930, 52, 710. (b) Takiyama, E.; Niikura, I.; Hatano, Y. Japan Patent 189823, 1992. (c) Miura, M.; Watanabe, H.; Fujiwara, M. Japan Patent 53695, 1995. (d) Ito, H.; Yamamoto, N.; Hiroji, F.; Jojima, M. Japan Patent 71641, 1997. (e) Takasu, A.; Oishi, Y.; Iio, Y.; Inai, Y.; Hirabayashi, T. Macromolecules 2003, 36, 1772. (f) Takasu, A.; Hirabayashi, T. Japan Patent 306535, 2003. (g) Takasu, A.; Oishi, Y.; Iio, Y.; Inai, Y.; Hirabayashi, T. Polym. Prepr. (Am. Chem. Soc., DiV. Polym. Chem.) 2003, 44 (2), 629. (h) Takasu, A.; Iio, Y.; Oishi, Y.; Hirabayashi, T. Macromolecules, in press. (3) (a) Fischer, R. F. J. Polym. Sci. 1960, 44, 155. (b) Sakai, S.; Ito, H.; Ishii, Y. Kogyo Kagaku Zasshi 1968, 71, 186. (c) Maeda, Y.; Nakayama, A.; Kawasaki, N.; Hayashi, K.; Aiba, S.; Yamamoto, N. Polymer 1997, 38, 4719. (4) Takasu, A.; Ito, M.; Inai, Y.; Hirabayashi, T.; Nishimura, Y. Polym. J. 1999, 31, 961.
1712
Biomacromolecules, Vol. 6, No. 3, 2005
(5) (a) Kolattukudy, P. E. Science 1980, 208, 990. (b) Warwel, S.; Demes, C.; Steinke, G. J. Polym. Sci.: Part A, Polym. Chem. 2001, 39, 1601. (6) (a) Takenouchi, S.; Takasu, A.; Inai, Y.; Hirabayashi, T. Polym. J. 2001, 33, 746. (b) Takenouchi, S.; Takasu, A.; Inai, Y.; Hirabayashi, T. Polym. J. 2002, 34, 36. (c) Takenouchi, S.; Takasu, A.; Inai, Y.; Hirabayashi, T. Polym. J. 2002, 34, 882. (7) (a) Dirlikov, S. K. In Emerging Technologies for Materials and Chemicals from Biomass; Rowell, R. M., Shults, T. P., Narayan, R., Eds.; ACS Symposium Series; American Chemical Society: Washington, DC, 1992; p 231. (b) Okada, M.; Okada, Y.; Aoi, K. J. Polym. Sci.: Part A, Polym. Chem. 1995, 33, 2813. (c) Yokoe, M.; Okada, M.; Aoi, K. J. Polym. Sci.: Part A, Polym. Chem. 2003, 41, 15. (8) (a) Takasu, A.; Niwa, T.; Itou, H.; Inai, Y.; Hirabayashi, T. Macromol. Rapid Commun. 2000, 21, 764. (b) Takasu, A.; Itou, H.; Takada, M.; Inai, Y.; Hirabayashi, T. Polymer 2002, 43, 227. (c) Takasu, A.; Takada, M.; Itou, H.; Hirabayashi, T.; Kinoshita, T. Biomacromolecules 2004, 5, 1029.
Takasu et al. (9) Charette, A. B.; Cote, B. Tetrahedron Asymmetry 1993, 4, 2283. In this report, they mentioned that the carbohydrate acts as a chiral auxiliary. (10) Horton, D.; Wolfrom, M. L. J. Am. Chem. Soc. 1962, 27, 1794. (11) Anderson, W. K.; Veysoglu, T. J. Org. Chem. 1973, 38, 2267. (12) Preliminary result: Morimoto, Y.; Takasu, A.; Takenouchi, S.; Inai, Y.; Hirabayashi, T. Polym. Prepr. Jpn. 2003, 52, E365. (13) Aida, T.; Inoue, S. J. Am. Chem. Soc. 1985, 107, 1358. (14) Oishi, M.; Aratake, S.; Yamamoto, H. J. Am. Chem. Soc. 1998, 120, 8271. (15) Maruoka, K.; Itoh, H.; Sakura, M.; Nonoshita, K.; Yamamoto, H. J. Am. Chem. Soc. 1988, 110, 3588. (16) Kobayashi, S.; Uyama, H.; Kimura, S. Chem. ReV. 2001, 101, 3793.
BM0491826
