chapter 2 palladium catalysts in suzuki cross- coupling reaction

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2.2. The Suzuki Reactions The coupling reactions of organoboron compounds with aryl, alkenyl, and alkynyl halides, which is referred to as Suzuki or Suzuki-Miyaura reaction, was first applied by Suzuki and Miyaura. In their study, cross-coupling reactions of 1- alkenylboronic esters and 1-bromo or 1-iodo-1-alkenes were performed. Later on, the methodology has found wide acceptance for the synthesis of biaryl reagents. Ar-X + Ar'-B(OH) 2 X = Halogen, OTf Pd, Base Ar-Ar' Figure 2.3. General representation of Suzuki reaction The Suzuki coupling reactions have many advantages (Suzuki 2005, Suzuki 1999, Kotha et al. 2002). These are; • The reactants are readily available, nontoxic, and air-stable. • Reactions are largely unaffected by the presence of water. • Reactions can be performed under mild conditions and are amenable to a variety of reaction conditions, including the use of aqueous solvents and substrate supports. • The boron-containing byproduct is environmentally safe and can be easily removed after the reaction when compared to byproducts of other organometallic reagents. • Most important of all, the coupling reaction proceeds with high regio- and stereo selectivity, and is little affected by steric hindrance. It does not affect other functional groups in the molecule. 8
2.2.1. Mechanism of Suzuki Coupling Reactions The catalytic cycle of Suzuki reaction involves three steps, oxidative addition of a halide, followed by transmetallation and then reductive elimination of the two carbon ligands added to the palladium. A general catalytic cycle for the Suzuki cross-coupling reaction is depicted in Figure 2.4. Reductive Elimination R L Pd +2 R' R- R' L Pd 0 Transmetallation R RX L Pd +2 X XB(OH) 3 R'B(OH) 2 + Base L Oxidative Addition Figure 2.4. A general catalytic cycle for the Suzuki cross-coupling reaction 2.2.1.1. Oxidative Addition In an oxidative addition step an electrophilic compound X-Y adds to a metal complex. In this step, the XY bond is broken and two bonds are formed; M-X and M-Y, and meanwhile, oxidation state of the metal is raised by two. The coordination number of the metal also increases by two (Tsuji 1995). 9
Page 1 and 2: SHORT-TIME SUZUKI REACTIONS OF ARYL
Page 3 and 4: ACKNOWLEDGEMENTS Firstly, I’d lik
Page 5 and 6: ÖZET ARİL HALOJENÜRLERİN HAVA A
Page 7 and 8: 3.2.2. Catalysts Anchored to Inorga
Page 9 and 10: LIST OF FIGURES Figure Page Figure
Page 11 and 12: Figure A.27. 13 C NMR of 4-cyanobip
Page 13 and 14: CHAPTER 1 INTRODUCTION The palladiu
Page 15 and 16: CHAPTER 2 PALLADIUM CATALYSTS IN SU
Page 17 and 18: 2.1.2. The Coordination Geometry of
Page 19: R 1 R 1 4. Sonogashira Reaction: H
Page 23 and 24: As a result, organic group or hydri
Page 25 and 26: 2.2.2.2. Halogen Effect Nearly all
Page 27 and 28: found to be excellent complexes for
Page 29 and 30: R Table 2.2. Examples from literatu
Page 31 and 32: L R Pd X R Pd L OR'' X L L + OR' R'
Page 33 and 34: omides and iodides is performed eff
Page 35 and 36: times for the transformation of a l
Page 37 and 38: R Br + (HO) 2B R' 5% Pd(OAc) 2 15%
Page 39 and 40: of insoluble solids are among the m
Page 41 and 42: could be reused multiple times. The
Page 43 and 44: 3.2.2. Catalysts Anchored to Inorga
Page 45 and 46: SO 2NH N Pd SO 2 N SO 2 NH NH H O1.
Page 47 and 48: utilized them in Heck and Suzuki co
Page 49 and 50: Smith et al introduced the use of P
Page 51 and 52: • Complexes immobilized in zeolit
Page 53 and 54: 3.3.3. Preparation of Zeolite-Suppo
Page 55 and 56: CHAPTER 4 EXPERIMENTAL STUDY 4.1. P
Page 57 and 58: temperature, the catalyst was recov
Page 59 and 60: amount of both reactant and product
Page 61 and 62: 4-Methoxybiphenyl: 1 H NMR (400 MHz
Page 63 and 64: 51 Table 4.1. Purification of coupl
Page 65 and 66: CHAPTER 5 RESULTS AND DISCUSSIONS I
Page 67 and 68: Table 5.2. The effect of base on Pd
Page 69 and 70: Table 5.4. The Optimization of Pd-N
Page 71 and 72:
H 3COC Table 5.5. Effect of zeolite
Page 73 and 74:
Table 5.6. Pd(NH3)4 2+ -loaded NaY
Page 75 and 76:
The type of other organic co-solven
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yield was very low (Table 5.8, entr
Page 79 and 80:
evealed excellent reactivity toward
Page 81 and 82:
CHAPTER 6 CONCLUSIONS In this thesi
Page 83 and 84:
REFERENCES Albisson, D.A., Bedford,
Page 85 and 86:
Choudary, B.M., Madhi, S., Chowdari
Page 87 and 88:
Heiden, M. Plenio, H. 2004. ‘‘H
Page 89 and 90:
Coupling Reactions of Aryl Chloride
Page 91 and 92:
Phan, N.T.S., Brown, D.H., Styring,
Page 93 and 94:
Wolfe, J.P., Singer, R.A., Yang, B.
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Figure A.1. 13 C NMR of 1-phenylnap
Page 97 and 98:
Figure A.3. 13 C NMR of 2-acetylbip
Page 99 and 100:
Figure A.5 . 13 C NMR of 2-methoxyb
Page 101 and 102:
Figure A.7. 13 C NMR of 2-methylbip
Page 103 and 104:
Figure A.9. 13 C NMR of 2-phenylnap
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Figure A.11. 13 C NMR of 3-acetylbi
Page 107 and 108:
Figure A.13. 13 C NMR of 3-methoxyb
Page 109 and 110:
Figure A.15. 13 C NMR of 3-phenylpy
Page 111 and 112:
Figure A.17. 13 C NMR of 4-acetyl-4
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Figure A.19. 13 C NMR of 4-methoxyb
Page 115 and 116:
Figure A.21. 13 C NMR of 4-methylbi
Page 117 and 118:
Figure A.23. 13 C NMR of 4-phenylbe
Page 119 and 120:
Figure A.25. 13 C NMR of 4-acetylbi
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Figure A.27. 13 C NMR of 4-cyanobip
Page 123 and 124:
Figure A.29. 13 C NMR of 4-nitrobip
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Figure A.31. 13 C NMR of 4-phenylan
Page 127 and 128:
APPENDIX B MASS SPECTRUMS OF SUZUKI
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Figure B.2. Mass spectrum of 2-acet
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Figure B.4. Mass spectrum of 2-meth
Page 133 and 134:
Figure B.6. Mass spectrum of 3-acet
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Figure B.8. Mass spectrum of 3-phen
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Figure B.10. Mass spectrum of 4-phe
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Figure B.12. Mass spectrum of 4-met
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Figure B.14. Mass spectrum of 4-cya
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Figure B.16. Mass spectrum of 4-met
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