SOLID-PHASE SYNTHESIS OF PURINE DERIVATIVES FU HAN (M.Sc., FUDAN UNIVERSITY) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2006 ACKNOWLEDGEMENTS A very special thank you to my supervisor, Dr. Lam Yulin for her guidance, encouragement and patience, which have been a tremendous help for me throughout the entire course of my Ph.D. study. She showed me her wide knowledge and stimulating suggestions during many hours of discussions we had. And most of all she gave me untiring help during my difficult moments. I would like to gratefully acknowledge the support of Dr. Teresa Tan in Dept. of Biochem., who gave me the chance to the biological test in her lab. My special thanks to Yang Fei for her help on biological experiments. And I also want to thank Dr. Go Mei Lin and Leng Zhijin for their help on microwave-assistant reactions. I also wish to thank all my group members, Madam Liang Eping, Kong Hah Hoe, Mark Tan Kheng Chuan, Makam Shantha Kumar Raghavendra, He Rongjun, Gao Yongnian, and Soh Chai Hoon⎯for all the help and interesting hints. Their support has been great. I want to express my gratitude to Han Yanhui and Peggy Ler, for their help with performing NMR spectra analyses. And thanks to Wong Lai Kwai and Lai Hui Ngee, who have helped me with mass spectral analyses. I am deeply indebted to my husband, whose patience and understanding I am very thankful for. My deepest gratitude is reserved for my parents for their long-distance support and love. I would like to thank National University of Singapore for awarding me a research scholarship to pursue my doctorate degree. TABLE OF CONTENTS i TABLE OF CONTENTS SUMMARY iv LIST OF TABLES vi LIST OF FIGURES vii LIST OF ABBREVIATIONS ix xiv LIST OF PUBLICATIONS CHAPTER 1: INTRODUCTION 1.1 Solid-phase synthesis (SPS) 1.1.1 Solid supports 1.1.2 Linkers 1.1.3 Reaction monitoring in solid-phase synthesis 13 1.1.4 Solid-phase synthetic libraries---from peptides to small organic molecules 13 1.2 Solid-phase synthesis of purine 15 1.2.1. SPS of purines based on halogenated/aminated purine 16 1.2.2. SPS of purine based on purine ring construction 24 1.3 Purpose of the research work in this thesis 27 1.4 References 28 CHAPTER 2: DESIGN, SYNTHESIS AND BIOLOGICAL EVALUATION OF 2,9DISUBSTITUTED-6-OXOPURINES AS RESISTANCE PROTEIN (MRP4/ABCC4) INHIBITORS OF MULTIDRUG 31 i 2.1 Introduction 31 2.1.1 Importance of purine 31 2.1.2 Multidrug resistance protein (MRP) 32 2.2 Outline of our synthetic strategy 33 2.3 Results and discussions 34 2.3.1 Solution-phase study 34 2.3.2 Solid-phase Study 42 2.3.3 Biological evaluation of 2,9-disubstituted-6-oxopurines as MRP4 inhibitor 51 2.4 Conclusions 55 2.5 Experimental 55 2.6 References 74 CHAPTER 3: TRACELESS SOLID-PHASE SYNTHESIS OF 1,7-DISUBSTITUTED PURINES 77 3.1 Introduction 77 3.2 Outline of our strategy 78 3.3 Results and discussions 79 3.3.1 Solution-phase synthesis study 79 3.3.2 Solid-phase study 88 ii 3.4 Conclusion 91 3.5 Experimental 92 3.6 References CHAPTER 4: 104 TRACELESS SOLID-PHASE SYNTHESIS OF VARIOUS SUBSTITUTED PURINES FROM p-BENZYLOXYBENZYLAMINE (BOBA) RESIN 105 4.1 Introduction 105 4.2 Outline of our strategy 106 4.3 Results and discussions 107 4.3.1 Solution-phase study towards 1,7,8-trisubstituted purines 107 4.3.2 Solution-phase study of other various substituted purines 117 4.3.3 Solid-phase study 131 4.4 Conclusions 137 4.5 Experimental 139 4.6 References 163 APPENDIX A: X ray crystal data 164 APPENDIX B: Spectral analyses 176 iii SUMMARY This thesis reports the development of novel methodologies for the solid-phase synthesis of purine derivatives. The first project involves the solid-phase synthesis of 2,9-disubstituted-6-oxopurines using Wang resin. The synthetic strategy involves loading 6-chloropurine scaffolds directly onto the solid support via an ether linker. Following this, combinatorial modifications include Mitsunobu alkylation at the N9 position, amination or Sonogashira coupling at the C2 position, bromination and subsequent alkylation at the C8 position were carried out. Then resin was eventually cleaved and 2,9-disubstituted-6-oxopurines were released. A small library of purine derivatives was prepared and overall yields obtained were 24-70%. The effects of these compounds on multidrug resistance protein (MRP4/ABCC4) facilitated bimane-GS efflux were examined. Compounds 2-16 and 225d were active in inhibiting MRP4 mediated efflux of the bimane-glutathione conjugate. In addition, both compounds were also able to reverse MRP4 mediated resistance to the anti-cancer drug 6-thioguanine. The second project focuses on the investigation of the regioselective solid-phase synthesis of N7-substituted purine using REM resin. The synthetic strategy was devised to anchor the REM resin at N9 of 6-chloropurine via Michael addition, leaving N7 as the steric priority for alkylation. Subsequent hydrolysis of 6-chloride was carried out followed by alkylation at N1. The resin bound N1-substituted purine was then quaternized at N7 with different alkylation agents. The 1,7-disubstituted-6-oxopurine derivatives were released from the resin via Hofmann elimination. With this method, a library of 15 1,7-disubstituted-6-oxopurines was synthesized in high purity and good iv yields. This study gives the first example of a highly regioselective solid-phase synthesis of 1,7-disubstituted-6-oxopurine derivatives. The third project centers on widening the solid-phase synthesis of purines based on the purine ring construction strategy. The synthetic strategy was designed to load the 5amino-4,6-dichloropyrimidine onto BOBA resin via an amine linker to construct the diamine key intermediate for elaboration to various substituted purines. After cyclization, the N7 position possesses the steric priority to be alkylated. This, in turn, resulted in a regioselective N7 alkylation being achieved. At the end of the reaction, the BOBA linker was easily cleaved and the target purines were released. During this study, we have also extended the use of the key intermediate polymer supported diamine for other solid-phase synthesis including 1,7,8-trisubstituted purines, 8-unsubstituted purines, 8-azapurines and [i]-condensed purines. In all these three projects, solid-phase-oriented synthesis in solution was examined to establish the requisite solid-phase reaction conditions. v LIST OF TABLES Table 1.1 Acid labile solid-phase linkers Table 2.1 Synthesis of compound 2-4a 36 Table 2.2 Effects of 2-16 and 2-25d on bimane-GS efflux 52 Table 2.3 Viability of M and V following exposure to 2-16 and 2-25d 53 Table 2.4 IC50 for 6TG in the presence of the purine derivatives 54 Table 2.5 Effects of inhibitors on MRP4-mediated efflux of bimane-GS 54 Table 3.1 Synthesis of compound 3-2 80 Table 3.2 Solution-phase synthesis of compound 3-5 86 Table 4.1 Synthesis of compound 4-2a 109 Table 4.2 Various ring closure conditions applied on 4-9 112 Table 4.3 Cyclization with aldehyde 114 Table 4.4 Different hydrolysis conditions of 4-13a 120 vi LIST OF FIGURES Figure1.1 Illustration of a solid-phase synthesis Figure 1.2 Structure of Wang resin Figure 1.3 Silyl linkers for traceless SPS Figure 1.4 Purine structure and numbering 16 Figure 2.1 Structures of hypoxanthine and guanine 31 Figure 2.2 X ray crystal structure of 2-3 35 Figure 2.3 X ray crystal structure of compound 2-4b 38 Figure 2.4 Library of 6-oxopurine derivatives 45 Figure 2.5 X ray Crystal Structure of 2-23a 46 Figure 2.6 X ray Crystal Structure of 2-23b 46 Figure 2.7 X ray Crystal Structure of 2-23d 47 Figure 2.8 NOESY spectrum of 2-25a 49 Figure 2.9 NOESY spectrum of 2-26 50 Figure 2.10 Structure of compound 2-6 58 Figure 2.11 Structure of compound 2-22e 67 Figure 3.1 9-H and 7-H purine 77 Figure 3.2 NOESY spectrum of compound 3-4 83 Figure 3.3 NOESY spectrum of compound 3-4a 84 Figure 3.4 NOESY spectrum of compound 3-4b 85 Figure 3.5 Library of 1,7-disubstituted-6-oxopurine 90 Figure 3.6 X-ray crystal structure of 3-6f 91 vii 8.4 8.0 7.6 7.2 6.8 6.4 6.0 5.6 5.2 4.8 1.5904 1.5774 6.2890 3.3137 3.3100 3.3072 0.9461 4.8281 4.8096 4.8059 4.7929 4.7791 4.7652 8.0833 1.0000 Integral 8.8 4.4 4.0 3.6 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 (ppm) 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 90 85 80 75 70 65 60 55 50 45 22.6850 49.5139 49.3426 49.1713 49.0000 48.8287 48.6574 48.4861 106.9187 124.9474 139.5502 149.6565 159.0706 Spectrum 2.5 1HNMR of 2-23d 40 35 30 25 20 15 10 (ppm) Spectrum 2.6 13CNMR of 2-23d 181 160 150 140 130 120 110 100 90 80 3.6 70 3.2 2.8 60 2.4 50 2.0 40 1.6 1.2 30 0.8 20 9.1464 4.0 13.8135 4.4 20.7558 4.8 28.7265 5.2 33.2611 5.6 37.0790 6.0 49.8571 49.5688 49.2883 49.0000 48.7195 48.4312 48.1507 45.0107 6.4 69.3436 6.8 76.8702 7.2 97.6035 7.6 125.2244 139.8646 8.0 142.8332 8.4 149.8923 158.9383 8.8 (ppm) 0.4 0.0 Spectrum 2.7 1HNMR of 2-25a (ppm) 10 Spectrum 2.8 13CNMR of 2-25a 182 3.3970 3.2702 2.4276 4.4653 2.3478 1.0000 Integral 1.4157 1.3901 1.3646 1.3391 1.3147 1.2903 1.1290 1.1046 1.0790 0.9908 0.9665 0.9421 1.8997 1.8753 1.8509 1.8440 1.8254 1.8184 1.7999 1.7929 1.7743 1.7685 3.3204 3.3158 3.3100 3.3042 3.2996 4.2398 4.2154 4.1910 4.8433 8.0946 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 90 4.4 85 4.0 80 75 3.6 70 3.2 65 60 2.8 55 2.4 50 45 2.0 40 35 1.6 30 1.2 25 20 15 9.3256 4.8 13.9460 5.2 20.8337 5.6 28.9914 6.0 32.8949 6.4 37.1647 6.8 49.8493 49.5688 49.2883 49.0000 48.7195 48.4312 48.1507 44.9718 7.2 69.4839 7.6 101.5616 8.0 124.9906 8.4 147.2666 158.3461 8.8 (ppm) 0.8 0.4 Spectrum 2.9 1HNMR of 2-26 (ppm) 10 Spectrum 2.10 13CNMR of 2-26 183 2.9600 2.7642 2.0132 4.3145 1.9664 1.0000 Integral 1.4110 1.3866 1.3611 1.3356 1.1452 1.1208 1.0953 0.9966 0.9723 0.9467 1.8881 1.8637 1.8405 1.8277 1.8150 1.8034 1.7906 1.7790 3.3158 3.3100 3.3042 4.3187 4.2943 4.2699 4.8561 8.0609 175 170 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 90 85 80 75 70 3.6 65 60 3.0 55 50 2.4 45 40 1.8 35 1.2 30 25 20 13.2966 13.1720 4.2 19.4831 19.1948 4.8 32.9312 31.8482 31.2483 5.4 42.1564 6.0 47.2598 6.6 49.8544 7.2 66.8399 7.8 77.4207 77.0000 76.5715 8.4 113.8227 9.0 128.3305 128.2136 9.6 134.9221 140.9605 10.2 146.3133 10.8 151.9387 151.1050 169.6176 11.4 (ppm) 0.6 0.0 Spectrum 3.1 1HNMR of 3-5 (ppm) 15 10 Spectrum 3.2 13CNMR of 3-5 184 6.0000 4.3341 2.2609 2.3012 1.8084 1.9701 1.8110 1.8261 1.8778 4.5143 0.8725 0.8897 Integral 2.0459 2.0227 1.9972 1.9716 1.9461 1.8045 1.7801 1.7546 1.7302 1.7047 1.4679 1.4435 1.4191 1.3936 1.3692 0.9989 0.9746 0.9502 3.2624 3.2415 3.2194 4.0923 4.0680 4.0424 5.0871 4.8619 4.8410 4.8190 4.6402 4.6147 4.5903 7.3180 7.3064 7.2600 8.2315 10.6308 165 160 155 150 145 140 135 130 125 120 115 110 105 5.2 100 95 4.8 90 4.4 85 4.0 80 75 3.6 70 3.2 65 2.8 60 55 2.4 50 2.0 45 1.6 40 35 1.2 30 25 13.9044 5.6 22.4127 6.0 31.5287 29.7601 28.7004 26.4643 6.4 46.5586 6.8 49.3012 7.2 77.4207 77.0000 76.5715 7.6 119.1910 8.0 132.2963 8.4 142.8928 8.8 146.6872 156.2786 154.1281 152.2114 9.2 (ppm) 0.8 20 0.4 15 0.0 Spectrum 3.3 1HNMR of 3-6d (ppm) 10 Spectrum 3.4 13CNMR of 3-6d 185 1.3147 1.3007 1.2926 1.2381 1.2218 0.8597 0.8376 0.8144 9.0257 3.2259 1.7592 1.7349 1.7105 4.0029 3.9786 3.9542 6.1155 6.0958 6.0807 6.0760 6.0610 6.0389 6.0238 6.0192 6.0052 5.9855 5.2983 5.2960 5.2647 5.2612 5.2310 5.2287 5.1741 5.1718 5.0511 5.0465 5.0314 5.0279 7.2600 8.0040 7.9564 2.2664 2.1932 2.1349 2.2681 1.0926 1.0775 1.0000 Integral 8.4 8.0 7.6 7.2 6.8 6.4 6.0 5.6 5.2 4.8 2.4766 2.4684 2.4603 0.9854 4.7725 4.7644 2.1511 5.5525 2.2961 7.2971 7.2855 7.2739 7.2600 5.2344 7.8613 8.2408 8.8 1.0325 1.0000 Integral 9.2 4.4 4.0 3.6 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 (ppm) 175 170 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 13.1876 19.2260 34.5051 32.9780 46.9482 77.4285 77.0000 76.5793 76.4936 74.7015 114.4460 145.1835 143.2746 153.2165 156.7383 Spectrum 3.5 1HNMR of 3-6l 15 10 (ppm) Spectrum 3.6 13CNMR of 3-6l 186 8.0 7.6 7.2 6.8 6.4 6.0 5.6 3.5735 2.9161 5.5746 1.9981 7.3041 7.2797 4.8576 7.8497 8.0075 8.4 0.9566 1.0000 Integral 8.8 5.2 4.8 4.4 4.0 3.6 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 (ppm) 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 90 85 80 75 70 65 60 55 50 33.5078 50.5089 77.4285 77.0000 76.5793 114.9602 128.9616 128.4162 127.8162 135.6545 143.1889 146.6872 157.0655 154.7047 Spectrum 3.7 1HNMR of 3-6o 45 40 35 30 25 20 15 10 (ppm) Spectrum 3.8 13CNMR of 3-6o 187 160 150 140 130 120 110 100 90 80 3.5 70 3.0 60 2.5 50 2.0 40 1.5 30 1.0 20 13.8194 13.3176 4.0 19.8261 4.5 22.1358 5.0 32.4888 30.9096 29.0132 27.3676 26.7994 5.5 36.2743 6.0 48.8410 48.2507 6.5 70.0709 77.4206 77.0000 76.5794 76.4318 75.4208 7.0 113.3499 7.5 115.5562 8.0 129.5103 128.5584 128.0639 127.3187 125.5403 8.5 136.2991 9.0 146.7259 153.4188 151.3527 150.2753 159.2484 9.5 (ppm) 0.5 0.0 Spectrum 4.1 1HNMR of 4-5 (ppm) 10 Spectrum 4.2 13CNMR of 4-5 188 3.2027 3.0208 8.3204 2.4129 2.3643 1.0114 2.1073 2.1230 2.0826 2.2087 2.0568 2.3233 7.3295 1.0000 Integral 1.5143 1.4899 1.4656 1.4400 1.2601 1.2369 1.1614 1.1394 1.1266 0.9989 0.9746 0.9502 0.8480 0.8260 0.8016 2.0204 1.9960 1.9716 1.9461 2.5845 2.5764 2.5683 3.3030 3.2763 3.2496 4.4382 4.4115 4.3848 5.0174 4.9640 4.9559 5.6953 6.9431 6.9141 7.3703 7.3645 7.3505 7.3250 7.3169 7.2995 7.2704 7.2600 8.7388 5.2 170 165 160 155 150 145 140 135 130 125 120 115 110 105 100 4.8 95 4.4 90 85 4.0 80 3.6 75 70 3.2 65 60 55 49.0329 48.4721 5.6 55.2904 6.0 77.4206 77.0000 76.5720 6.4 114.1099 6.8 116.9804 7.2 120.9504 7.6 135.8933 133.6795 130.6909 128.8904 128.1377 127.7909 8.0 146.6152 8.4 156.2008 154.2896 153.9206 161.1891 8.8 (ppm) 2.8 2.4 50 45 2.0 40 1.6 35 30 1.2 25 0.8 20 15 0.4 Spectrum 4.3 1HNMR of 4-6g (ppm) 10 Spectrum 4.4 13CNMR of 4-6g 189 3.0328 2.9211 1.9951 1.0761 0.9538 2.0945 5.2936 2.0648 1.0000 Integral 3.8414 5.2779 5.2434 5.1968 5.0768 5.0691 5.0615 5.0297 4.9727 6.1725 6.1572 6.1391 6.1227 6.1155 6.1068 6.1002 6.0827 6.0651 6.0498 7.0003 6.9713 7.3219 7.3110 7.3005 7.2600 7.7191 7.7125 7.6901 8.1168 175 170 165 160 155 150 145 140 135 130 125 120 115 110 105 100 95 5.6 90 5.2 85 80 4.8 4.4 75 70 65 4.0 60 3.6 55 50 3.2 45 2.8 40 35 2.4 30 2.0 25 20 13.9200 6.0 17.6209 6.4 44.4081 6.8 62.6714 7.2 69.8708 7.6 77.4207 77.0000 76.5715 8.0 114.9135 8.4 130.5510 128.7200 128.4317 127.8240 127.2552 123.8270 8.8 136.7297 145.4874 9.2 152.4062 9.6 158.1018 156.4188 166.8906 10.0 (ppm) 1.6 15 1.2 Spectrum 4.5 1HNMR of 4-7 (ppm) 10 Spectrum 4.6 13CNMR of 4-7 190 3.4925 1.3553 1.3321 1.3089 1.8591 4.2873 4.2653 3.2128 4.6228 4.6042 1.7199 5.0499 5.3308 5.3134 5.2949 6.9605 6.9315 7.4330 7.4086 7.3749 7.3505 7.3343 7.2472 7.2182 8.1886 2.1167 2.1592 1.0466 2.1700 2.2431 5.3353 1.0000 Integral 165 160 155 150 145 140 135 130 125 6.4 120 6.0 115 110 5.6 105 5.2 100 95 4.8 90 4.4 85 80 4.0 3.6 75 70 65 3.2 60 2.8 55 50 45 14.7848 6.8 46.0443 7.2 70.0500 7.6 77.4207 77.0000 76.5715 8.0 115.4121 114.9914 136.5193 129.3278 128.6499 128.5720 128.0422 127.9720 127.3721 127.0059 8.4 151.3154 149.4922 148.9312 155.2345 158.8108 8.8 (ppm) 2.4 2.0 40 35 1.6 30 1.2 25 0.8 20 15 0.4 Spectrum 4.7 1HNMR of 4-8 (ppm) 10 Spectrum 4.8 13CNMR of 4-8 191 Integral 3.2829 2.4295 2.3842 2.3299 2.3021 5.7004 1.0000 2.6043 5.0279 5.3633 7.4016 7.3807 7.3656 7.3389 7.2635 7.2588 7.2391 7.2182 7.2113 7.1474 7.1219 6.9315 6.9280 6.9037 6.8746 8.0957 8.0899 8.7121 165 160 155 150 145 140 135 130 125 8.4 120 8.0 115 7.6 110 105 7.2 100 6.8 95 6.4 90 6.0 85 5.6 80 5.2 75 4.8 70 49.9635 49.1064 47.3845 8.8 69.8630 9.2 77.4207 77.0000 76.5715 9.6 115.3888 114.0175 10.0 131.0731 128.4162 127.8863 127.2630 124.9567 10.4 136.3323 10.8 139.9710 11.2 146.1574 151.9855 151.1829 159.3952 11.6 (ppm) 4.4 65 4.0 60 55 3.6 50 3.2 Spectrum 4.9 1HNMR of 4-16 45 2.4 40 35 30 1.6 25 20 13.3745 13.2343 2.0 19.5688 19.3195 32.1365 31.3496 2.8 1.2 0.8 15 10 0.4 (ppm) Spectrum 4.10 13CNMR of 4-16 192 6.2724 4.4604 2.1904 2.1828 2.0875 2.0694 2.2170 2.0311 2.1977 5.3223 2.0858 1.0322 1.0000 Integral 2.0320 2.0065 1.9821 1.9566 1.9310 1.7790 1.7546 1.7291 1.7059 1.6792 1.4331 1.4226 1.4075 1.3983 1.3832 1.3588 1.3483 0.9665 0.9583 0.9421 0.9340 0.9177 0.9096 4.1260 4.1016 4.0761 4.9850 4.6356 4.6100 4.5845 5.6419 6.9385 6.9095 8.4300 7.6547 7.6257 7.3633 7.3413 7.3204 7.2937 7.2856 7.2763 7.2635 10.8746 8.8 8.4 8.0 7.6 7.2 6.8 6.4 6.0 5.6 5.2 4.8 4.0 4.4 3.6 4.0 3.2 3.6 2.8 3.2 2.4 2.8 2.0 2.4 1.6 2.0 1.2 1.6 3.0000 4.4 1.4505 1.4261 1.4017 1.3750 1.3506 1.3344 1.3263 0.9792 0.9548 0.9305 4.8 2.0102 5.2 1.8445 5.6 1.7929 1.7685 1.7430 1.7186 1.6931 6.0 1.7999 6.4 4.0250 4.0006 3.9751 6.8 5.1997 7.2 5.5967 7.6 2.7686 7.5317 7.8439 8.0 7.3413 7.3227 7.2983 7.2600 8.0934 7.9913 1.1142 8.4 0.8104 Integral 8.8 (ppm) 0.8 1.2 0.4 0.8 0.0 Spectrum 4.11 1HNMR of 4-17d (ppm) 0.4 Spectrum 4.12 13CNMR of 4-17d 193 3.1653 2.3938 2.1302 2.0734 2.5956 1.4301 1.4054 1.3808 1.3550 1.3298 1.3140 1.3063 0.9589 0.9343 0.9102 1.7736 1.7489 1.7237 1.7155 1.6985 1.6733 4.0061 3.9820 3.9568 5.1829 5.5790 7.3025 7.2691 7.8394 1.1906 8.5287 8.0870 7.9780 1.0000 Integral 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 2.5000 4.2086 4.1738 4.1436 3.8627 2.4392 4.7228 4.6926 4.6578 2.1135 8.8052 1.0000 Integral 10.5 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 (ppm) 165 160 155 150 145 140 135 130 125 120 115 49.8486 49.5682 49.2804 49.0000 48.7122 48.4318 48.1440 45.3178 114.8445 148.5305 148.2501 159.5846 Spectrum 4.13 1HNMR of 4-22 110 105 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 (ppm) Spectrum 4.14 13CNMR of 4-22 194 165 160 155 150 145 140 135 130 125 120 6.0 115 110 5.5 105 100 5.0 95 4.5 90 85 4.0 80 75 3.5 70 65 3.0 60 55 2.5 50 45 40 35 3.0902 2.0975 4.1473 2.2944 1.0174 1.0000 Integral 2.0917 2.0 1.5 1.0 30 25 20 13.9931 6.5 20.6713 7.0 30.2938 7.5 49.8560 49.5682 49.4206 49.2878 49.0000 48.8672 48.7196 48.4318 48.1514 48.0555 8.0 117.0730 8.5 145.4534 144.5162 152.8105 151.0837 9.0 (ppm) 0.5 Spectrum 4.15 1HNMR of 4-24 (ppm) 15 10 Spectrum 4.16 13CNMR of 4-24 195 1.8637 1.8393 1.8138 1.7894 1.7639 1.5410 1.5167 1.4911 1.4656 1.4412 1.4168 1.0338 1.0094 0.9850 3.3204 3.3146 3.3100 3.3042 3.2996 4.2165 4.1840 4.1620 4.1388 4.1132 4.8805 4.8248 4.7946 4.7609 8.3511 8.5148 165 160 155 150 145 140 135 7.6 130 7.2 125 120 6.8 115 6.4 110 6.0 105 100 5.6 95 5.2 90 4.8 85 80 4.4 75 4.0 70 3.6 65 60 3.2 55 2.8 50 2.4 45 40 2.0 35 1.6 30 25 1.2 20 13.9415 8.0 20.7451 8.4 32.6034 8.8 49.5682 49.2804 49.0000 48.7196 47.5094 9.2 128.7469 153.7992 152.2275 156.9059 9.6 (ppm) 0.8 15 0.4 Spectrum 4.17 1HNMR of 4-35d (ppm) 10 Spectrum 4.18 13CNMR of 4-35d 196 2.9877 2.0446 2.0507 2.0274 1.0000 Integral 1.4215 1.3971 1.3716 1.3460 0.9769 0.9525 0.9282 1.7929 1.7685 1.7430 1.7349 1.7175 1.6919 3.3100 4.1132 4.0889 4.0633 5.0975 8.3766 [...]... Submitted to Journal of Combinatorial Chemistry 3 Traceless Solid- Phase Synthesis of N1,N7-Disubstituted Purines Han Fu and Yulin Lam Journal of Combinatorial Chemistry 2005 7(5) 734-738 CONFERENCE PAPER 1 Traceless Solid- Phase Synthesis of N1,N7-Disubstituted Purines Han Fu and Yulin Lam Pacifichem 2005, Honolulu, Hawaii, USA, December 15-20, 2005 2 Solid- phase Synthesis of 6-Oxopurine Derivatives Han... coupled to the solid support via the functionality present on the solid support Several modification steps can be performed to achieve the solid support bound final molecule and eventually it is cleaved from the solid support (Figure 1.1) Figure1.1 Illustration of a solid- phase synthesis This concept of solid- phase synthesis was first raised by R B Merrifield in 1963 for efficient peptides synthesis. [1]... from solutionphase ones, some modifications of the reaction conditions are still necessary to achieve better results in solid- phase reactions For example sometime a specific co-solvent should be added to the solid- phase reaction to allow the resin to achieve better swelling property 1.2 Solid- phase synthesis of purine The purine ring is a critical structural element in biology because of its potential... number of purine syntheses have been developed in solution.[21] Ever since Gray discovered the trisubstituted purine as cyclin-dependent kinase (CDK) inhibitors, [22] SPS of purines have been developed to cater to the demand of purine derivatives with higher diversity SPS has proved to be an effective and convenient technique to generate purine library From 1990’s various methods for the SPS of purine derivatives. .. halogenated/aminated purine is usually used Modification on such purine ring can generate purine libraries The second strategy is based on the construction of the purine ring This is achieved via the synthesis of substituted pyrimidine ring followed by closure of the imidazole ring or through the generation of the imidazole ring first followed by cyclocondensation of the pyrimidine ring 15 1.2.1 SPS of purines... requisite solid- phase reaction conditions This validation of the planned synthetic route is necessary to carry out successful corresponding reactions on the solid phase Normally the solution -phase synthetic route must provide all the intermediates and 14 target compound with good yield and high purity before it is transferred onto the solid support Meanwhile because of different nature of solid- phase reactions... trifluoroethanol 6TG 6-thioguanine THF tetrahydrofuran THP tetrahydropyran TLC thin layer chromatography TMS tetramethylsilane TsOH p-methylbenzenesulfonic acid xii LIST OF PUBLICATIONS 1 Traceless solid- phase synthesis of 1,7,8-trisubstituted purines Han Fu and Yulin Lam In preparation 2 Design, Synthesis and Biological Evaluation of Novel Purine Analogs as Inhibitors of Multidrug Resistance Protein 4 (MRP4/ABCC4)... Structure of 9-(4-(benzyloxy)benzyl)-6-chloro-8-hexyl9H -purine (4-12) 114 Figure 4.2 X ray crystal structure of 4-13a 119 Figure 4.3 X ray crystal structure of 4-18a 122 Figure 4.4 Structures of side products 4-25 and 4-26 125 Figure 4.5 NOESY of compound 4-21a 126 Figure 4.6 Two possible pathways of the cyclization of the pendant alcohol 127 Figure 4.7 NOESY of compound 4-21b 129 Figure 4.8 NOESY of compound... from the solid support.[19] 12 O O O O O N R 1 R1 HCl NHR2 toluene N O N R O 2 Scheme 1.11 Traceless SPS of 1,3-disubstituted-5,6-dihydropyrimidine-2,4-diones 1.1.3 Reaction monitoring in solid- phase synthesis Although the nature of solid- phase reaction makes it ‘blind’ to some extent and its reaction monitoring is not as easy as in solution, there are still some methods available for solid- phase reaction... 15-17, 2005 xiii CHAPTER 1: Introduction 1.1 Solid- phase synthesis (SPS) Solid- phase synthesis (SPS) is a methodology whereby the reactions take place on the molecule attached to an insoluble material referred to as a solid support Such a SPS is composed of a polymer bead (generally cross-linked, insoluble, polymeric material inert to the conditions of synthesis) and a linker (a bifunctional chemical . molecules 13 1.2 Solid-phase synthesis of purine 15 1.2.1. SPS of purines based on halogenated/aminated purine 16 1.2.2. SPS of purine based on purine ring construction 24 1.3 Purpose of the research. example of a highly regioselective solid-phase synthesis of 1,7-disubstituted-6-oxopurine derivatives. The third project centers on widening the solid-phase synthesis of purines based on the purine. reports the development of novel methodologies for the solid-phase synthesis of purine derivatives. The first project involves the solid-phase synthesis of 2,9-disubstituted-6-oxopurines using Wang