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290b. ........................................................................................................................................... 110 Scheme 4.37 Cyclocarbonylation reaction of allenynes 74f-i. ................................................... 110 Scheme 4.38 Arene complexation rationale for the diastereoselectivity in the cyclocarbonylation reaction........................................................................................................................................ 111 Scheme 4.39 Diversification potential of α-alkylidene cyclopentenones. ................................. 112 Scheme 4.40 Stetter reaction of 287a and 287b with butyraldehyde. ........................................ 113 Scheme 4.41 Attempted pyrrole synthesis and reduction of 205a and 206a.............................. 114 Scheme 4.42 Synthesis of pyrrole 298a...................................................................................... 115 Scheme 4.43 Formation of pyrrole 296 as a diastereomeric mixture. ........................................ 116 Scheme 4.44 Addition of glyoxylamides to 287b and subsequent reduction............................. 117 Scheme 4.45 Preparation of pyrroles from diketone 306. .......................................................... 118 Scheme 4.46 Unsuccessful examples of pyrrole formation........................................................ 119 Scheme 4.47 Comparison of the stability between alkyl-pyrrole 298a and acyl-pyrrole 308a.. 120 Scheme 4.48 Synthesis of a library of tricyclic pyrroles. ........................................................... 122 Scheme 4.49 Ir(I)-catalyzed cyclocarbonylation reaction by Shibata. ....................................... 130 Scheme 4.50 Rh(I) catalyzed formation of 4-alkylidene cyclopentenones. ............................... 130 Scheme 4.51 Rh(I)-mediated formation of α-alkylidene cyclopentenones. ............................... 132 Scheme 4.52 Synthesis and 31 P NMR data for [Rh(CO)2dppb]BF4 and related complexes....... 134 Scheme 4.53 Rh(I)-catalyzed cyclocarbonylation reaction of 74c. ............................................ 135 Scheme 4.54 Attempted cyclocarbonylation reaction of 328. .................................................... 137 Scheme 4.55 Attempted cyclocarbonylation reaction of 331. .................................................... 137 Scheme 4.56 Summary of reaction pathways available to allenic amino-esters. ....................... 140 xviii
1.0 Introduction 1.1 The Role of Diversity-Oriented Synthesis in Modern Biomedical Research Modern drug discovery efforts are based upon a deep understanding of the cellular pathways responsible for a particular disease. The extreme complexity of the cellular circuitry has made the goal of understanding all of its aspects a formidable challenge. Significant progress in this area has been made by using modern biochemical tools such as mutagenesis, which is commonly used to irreversibly modify proteins in order to understand their cellular function. However, there are many aspects of the cell’s biochemistry that remain a mystery. These include important signaling pathways based on dynamic protein-protein interactions that are particularly difficult to study. 1 Therefore, there is a tremendous need for innovative strategies to discover new cellular pathways and probe the function of various protein targets. Small organic molecules are useful research probes for studying cellular pathways. Small molecules are capable of interacting with macromolecules such as proteins generally in a reversible manner, thereby modulating their function. 2 Observing the effects that result from such interactions in designed assays can often lead to an understanding of the role a particular target plays in the cell. Additionally, if the protein is a known therapeutically relevant target, lead compounds for drug discovery can be identified. The great number of relevant protein targets and their immense structural diversity dictates that the small molecules screened against these 1
Page 1 and 2: TRANSITION METAL-CATALYZED REACTION
Page 3 and 4: Transition Metal-Catalyzed Reaction
Page 5 and 6: List of Abbreviations Ac acetyl AcO
Page 7 and 8: Table of Contents 1.0 Introduction.
Page 9 and 10: Appendix A : X-ray crystal structur
Page 11 and 12: Table 4.8 Rh(I)-catalyzed cyclocarb
Page 13 and 14: List of Schemes Scheme 1.1 Three fo
Page 15 and 16: Scheme 3.24 Preparation of amide-te
Page 17: Scheme 4.16 Formation of bicyclo[5.
Page 21 and 22: According to these guidelines, the
Page 23 and 24: Scheme 1.1 Three forms of diversity
Page 25 and 26: Another example from the Schreiber
Page 27 and 28: 1.1.1 Transition Metal-Catalyzed Re
Page 29 and 30: 37, , such reactions include transi
Page 31 and 32: the proximal olefin of allenyne 38
Page 33 and 34: 2.0 Design and Synthesis of the Piv
Page 35 and 36: The allenic amino acid derivatives
Page 37 and 38: This protocol proved particularly u
Page 39 and 40: ZnCl2, which results in a Zn-chelat
Page 41 and 42: Scheme 2.7 Synthesis of trisubstitu
Page 43 and 44: THF), the yield was increased from
Page 45 and 46: the terminus of the alkyne led to d
Page 47 and 48: N-Alkylation of the glycine-derived
Page 49 and 50: circumvent this issue, variants suc
Page 51 and 52: BINAP as a chiral ligand to obtain
Page 53 and 54: stereochemistry of the exocyclic ol
Page 55 and 56: 3.2 Rhodium(I)-Catalyzed Allenic Cy
Page 57 and 58: exocyclic olefin geometry is not re
Page 59 and 60: 3.2.1 Preparation of Enol-ether Tri
Page 61 and 62: Scheme 3.15 Synthesis of cycloisome
Page 63 and 64: Scheme 3.17 Cycloisomerization of a
Page 65 and 66: Scheme 3.19 Tandem cycloadditions o
Page 67 and 68: Scheme 3.21 Intermolecular Diels-Al
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attractive, since additional functi
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increased yield of the triene (47%)
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as an isobutyl-amide 155b was prepa
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group) demonstrated that this cyclo
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in 1M HCl/dioxane (1 : 1) for 1h, t
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ppm (dd, J = 7.1, 4.6 Hz, 1H) assig
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http://ccc.chem.pitt.edu/). Using f
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Notably, exclusive cycloisomerizati
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intermediate in the reaction we sou
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epulsive dipole interactions (Schem
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Table 3.4 Diels-Alder reactions of
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allenic Alder-ene reaction, ene-all
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Figure 3.4 Examples of natural prod
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species onto the proximal double bo
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Scheme 3.49 Rh(I)-catalyzed ene rea
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y Magnus 144 and it involves the in
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usually is DMSO. Heating to 100 ºC
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that require high pressures of CO.
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In contrast to the Mo(CO)6-mediated
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Scheme 4.15 Rh(I)-catalyzed allenic
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4.2 Rhodium(I)-Catalyzed Cyclocarbo
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lack of double bond selectivity, si
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Table 4.2 Cyclocarbonylation reacti
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Notably, the allenic cyclocarbonyla
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Scheme 4.22 Cyclocarbonylation reac
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neat or in solution. This decomposi
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the newly synthesized fulvenes (e.g
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stereocenters and mixture of E/Z is
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proximal double bond to give α-alk
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the methyl ester and Ha are syn. Sc
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that the major diastereomer in the
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We were motivated to first examine
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Scheme 4.42 Synthesis of pyrrole 29
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periodic acid (H5IO6). 209 These hi
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eaction failed to go to completion,
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4.5.2 Synthesis of a Library of Tri
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diketones 312{1-3,1-2} in yields ra
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Figure 4.2 Distribution for physico
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tricyclic pyrrole 314{3,2,26} (Figu
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4.6 Synthesis of α-Alkylidene Cycl
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anched and linear carboxylic acid i
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eactivity of the species prepared i
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considerably lower than the ratio o
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diastereomer. Next, allenyne 328 wa
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Conclusions In summary, we have dem
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Experimental Section General Method
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General procedure A for esterificat
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F Bz N H 56f 2-Benzoylamino-3-(4-fl
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MeO2C Bz N H 58c 2-Benzoylamino-2-m
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MeO MeO2C Bz N H 58e 2-Benzoylamino
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mL) and MeOH (10 mL) instead of sat
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hexanes-EtOAc, 19 : 1 to 4 : 1, v/v
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which was immediately used in the C
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Boc TMS N H Bn 64f tert-Butyl-1-((4
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MeI (38 µL, 0.62 mmol). Yield 65a
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with brine and concentrated under v
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H MeO 2C • H Bn NHBoc tert-Butyl-
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TMS MeO 2C • 70 H H NHBoc 2-tert-
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185 (10), 141 (21), 57 (100); EI-HR
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dispersion in mineral oil, 1.0 mmol
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EI-HRMS calcd for C30H26NO3 m/z [M-
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CbzN MeO 2C Me 73h 2-[Benzyloxycarb
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CbzN MeO 2C Me 2-(Benzyloxycarbonyl
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dispersion in mineral oil, 3.85 mmo
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completion of the addition, the rea
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BzN MeO 2C S 74h 2-(Benzoylprop-2-y
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BzN MeO 2C Bn 75b 2-(Allylbenzoylam
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BzN MeO 2C TBSO 75e 2-(Benzoylbut-2
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Hz, 1H), 5.85 (s, 1H), 5.52 (dd, J
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1H), 3.69 (s, 3H), 1.58 (d, J = 7.1
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µmol), [Rh(CO)2Cl]2 (1 mg, 3 µmol
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1.25 (m, 6H), 0.88 (t, J = 6.9 Hz,
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6.72 (d, J = 7.6 Hz, 0.5H), 6.68 (d
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BzN MeO2C Bn 122a Methyl-2-(N-(but-
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Bz N MeO2C Bn 1-Benzoyl-2-benzyl-4-
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13.9, 5.3 Hz, 1H), 2.51-2.47 (m, 1H
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15 min the solvent was removed unde
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Benzoyl chloride (0.169 mL, 1.46 mm
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mg, 0.11 mmol), [Rh(CO)2Cl]2 (4 mg,
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mL). kk The aqueous layer was extra
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ºC. After quenching the reaction b
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129.8, 129.0, 128.7, 128.4, 126.2,
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MeO 2C O O O N H N R 1 O N Ph [10c-
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The crude residue was purified by f
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14.4 Hz, 1H), 3.49-3.39 (m, 2H), 3.
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1H), 5.49 (dd, J = 17.3, 1.8 Hz, 1H
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was stirred at rt for 1 h when it w
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BzN HOOC 2-(N-(but-2-ynyl)benzamido
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°C and DIBAL-H (0.440 mL of a 1.0M
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129 (62), 91 (100); EI-HRMS calcula
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(d, J = 18.0 Hz, 1H), 4.14 (d, J =
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4.98 (dt, J = 7.7, 5.1 Hz, 1H), 4.1
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N Bz MeO2C OTBS 214 1-Benzoyl-2-(te
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270a (major diastereomer-eluting fi
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CDCl3): δ 7.42-7.17 (m, 13H), 7.04
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18.6 Hz, 1H), 4.34 (d, J = 18.0 Hz,
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Bz N MeO2C 2-Benzoyl-3,7-dimethyl-6
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v/v) afforded a mixture of compound
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(435 mg, 1.21 mmol), DMSO (429 µL,
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4.02 (s, 1H), 3.88 (s, 3H), 1.82 (s
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(207 mg, 96%) consisting of 287e (7
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procedure O, using: 74f (110 mg, 0.
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Bz N O H CO2Me BocN 287i 3-(2-Benzo
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4.17 (d, J = 15.0 Hz, 1H), 4.10 (d,
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137.1, 136.9, 130.4, 129.8, 128.5,
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H BzN MeO2C Bn H N C3H7 298b CO 2Me
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NMR (75 MHz, CDCl3): δ 172.3, 169.
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following the general procedure Q,
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H BzN MeO2C Bn H 5-Benzoyl-1,4-dibe
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119.9, 114.1, 109.9, 108.6, 73.0, 5
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4.11 (m, 1H), 4.07-3.98 (m, 1H), 3.
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126.8, 126.2, 109.0, 72.9, 58.7, 56
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NMR (75 MHz, CDCl3): δ 172.2, 169.
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3.0 Hz, 1H), 5.82-5.80 (m, 1H), 5.2
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87%). The diastereomeric ratio (288
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APPENDIX A: X-ray crystal structure
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APPENDIX B: X-ray crystal structure
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APPENDIX C: X-ray crystal structure
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APPENDIX D: X-ray crystal structure
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APPENDIX E: X-ray crystal structure
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APPENDIX F: QikProp property predic
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1 H and 13 C NMRs of 74b 293
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1 H and 13 C NMRs of 111a 295
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Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
1 H and 13 C NMRs of 270h 303
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1 H and 13 C NMRs of 307 307
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1 H and 13 C NMRs of 308n 309
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10. (a) Burke, M. D.; Schreiber, S.
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Hu, Y. J. Comb. Chem. 2006, 8, 286.
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49. For reviews on reactions of all
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69. (a) Trost, B. M.; Lautens, M.;
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containing cross-conjugated trienes
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Vaillancourt, J.; Rasper, D. M.; Ta
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130. Oppolzer, W.; Snieckus, V. Ang
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149. (a) Hicks, F. A.; Buchwald, S.
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Maiese, W. M. J. Antibiot. 2000, 53
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192. The mechanism of decomposition
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Boger, D. L.; Boyce, C. W.; Labroli
Page 351:
Generated Inhibitors of Human Mitog
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