My PhD dissertation - Institut Fresnel

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50 At first, bis(phenol ether) 7 was subjected to a double halogen/metal permutation followed by addition chlorodiphenylphosphine to form the well characterized MeO-BIPHEP 42 [16] in 64% yield. Since rotatory power obtained and those reported by R. Schmid et al. for enantiopure MeO-BIPHEP (ee > 99%) happened to be the same, no racemization must have occurred upon lithiation of the optically pure dibromobiphenyl 35. Furthermore, this result permitted the deduction of the enantiomeric excess of the resolved biphenol 31 (ee > 99%). On the other hand, the ease and rapidity to obtain ligand 42 in enantiopure form with good overall yield showed the efficiency of the method developed. Br Br O O (P)-(-)-35 LiC 4H 9 (2.0 eq.) Tol./DEE (9:1) - 75 °C to - 40 °C, 1 h Li Li O O ClPPh 2 (2.0 eq.) Tol., - 75 °C Ph2P Ph2P O O (P)-(+)-MeO-BIPHEP 42, 64% Another "BIPHEP-type" bisphosphine was prepared starting from diethoxyphenol ether 36. This substrate was consecutively treated with four equivalents of tert-butyllithium in tetrahydrofuran at -75 °C, and two equivalents of chlorodiphenylphosphine to afford (6,6’- diethoxybiphenyl-2,2’-diyl)bis(diphenylphosphine) ("EtO-BIPHEP"; 43) in high yield (85%). The enantiomeric excess of bisphosphine 43 thus produced was then determined by chiral High Pressure Liquid Chromatography (HPLC). Thus each pure atropisomer was compared with the racemic mixture under the same conditions, and ee was determined to be above 99%. Br Br O O (P)-(-)-36 LiC(CH 3) 3 (2.0 eq.) THF, - 75 °C, 30 min Li Li O O ClPPh 2 (2.0 eq.) Tol., - 75 °C Ph2P Ph2P O O (P)-(+)-43, 85% A single-crystal X-ray analysis has been carried out for (M)-(-)-43 (Figure 4) The dihedral angle θ (C8-C7-C6-C1) was determined to be of 73.9 ° which is slightly larger that the value found for its MeO-BIPHEP congener (70.3 °). X. Zhang [172] showed, for the asymmetric hydrogenation of β-ketoesters, that a change of only 3 ° in the biphenyl torsion angle could increase the enantioselectivities (ee) from 86% to 96% depending on the [ ] 197 .
51 substrates considered. In consequence, since the biphenyl dihedral angle is correlated to its natural bite angle (β) in the metal complexes [198 - 200] , the slight difference in dihedral angle observed between MeO-BIPHEP and bisphosphine 43, can be exploited to fine-tune a given reaction selectivity and increase ee of products obtained. Figure 4. Stereoscopic drawing of (M)-(-)-43. A last couple of enantiomerically pure bisphosphines was prepared in the biphenol series, starting from (P)-(-)- or (M)-(-)-2,2’-dibromo-6,6’-bis(methoxymethoxy) biphenyl (34). The usual organometallic treatment followed by addition of chlorodiphenylphosphine provided the expected chiral [6,6’-bis(methoxymethoxy)biphenyl-2,2’-diyl]bis (diphenylphosphine) ("MOMO-BIPHEP"; 44) in 69% yield, with ee > 99% according to chiral HPLC analysis. Br Br O O (P)-(-)-34 O O LiC(CH 3) 3 (2.0 eq.) THF, - 75 °C, 30 min Li Li O O O O ClPPh 2 (2.0 eq.) Tol., - 75 °C Ph2P Ph2P O O (P)-(+)-44, 69% O O
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Various Facets of Organophosphorus
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III Remerciements Je tiens à remer
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3.3.6 Relevance of the Data Assesse
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VII Literature References 115 Compo
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IX Version Abrégée Les composés
Page 21 and 22: 1 Introduction 1 The present thesis
Page 23 and 24: 3 research groups in the field are
Page 25 and 26: 5 However, this mechanism suffers f
Page 27: 7 At first, a double bromine/lithiu
Page 30 and 31: 10 Although the most frequently emp
Page 32 and 33: 12 The preparation of the latter ph
Page 34 and 35: protected to its dioxolane derivati
Page 36 and 37: N (S)-14 1) NBS, THF, - 75 °C 2) -
Page 39 and 40: 3 Alkaline Decomposition of Phospho
Page 41 and 42: 3.2 Alkyl Carbanions Stabilities in
Page 43 and 44: 3.3.1 Mechanistic Discussion on the
Page 45 and 46: 25 The assumption reported by these
Page 47 and 48: 27 However, in the eventuality of a
Page 49 and 50: 29 To prepare tertiary phosphines b
Page 51 and 52: 31 Table 4. Mixed tertiary alkylpho
Page 53 and 54: 33 were comparable to those obtaine
Page 55 and 56: 35 led to the formation of di-tert-
Page 57 and 58: 37 depending on the alkyl substitue
Page 59 and 60: 39 4 A Novel Access to Atropisomeri
Page 61 and 62: 41 Since the homocoupling of the ha
Page 63 and 64: 43 Few other attempts to selectivel
Page 65 and 66: 45 The second phenol ether 36 was f
Page 67 and 68: 47 The enantiomeric purity was chec
Page 69: 49 A second purpose of this derivat
Page 73 and 74: 53 Single-crystal X-ray analysis of
Page 75 and 76: 55 To convert atropisomer Ia into I
Page 77 and 78: 57 This finally allows one to use t
Page 79 and 80: the steric bulk and charge delocali
Page 81 and 82: 61 To check the reproducibility of
Page 83: 63 Figure 9. Full lineshape analysi
Page 86 and 87: 66 suitably substituted dilithiobip
Page 89: Experimental Part
Page 92 and 93: 70 deuterochloroform (CDCl3) unless
Page 94 and 95: 72 1 H NMR: δ = 7.32 (dddd, J = 9,
Page 96 and 97: 1 H NMR: δ = 6.96 (s, 3 H), 6.94 (
Page 98 and 99: 76 C21H21O9P (448.36) calcd. C 56.2
Page 100 and 101: 78 C12H12BrN (250.13) calcd. C 57.6
Page 102 and 103: 80 C13H13NO2 (215.25) calcd. C 72.5
Page 104 and 105: 82 3.1.1 Dialkyl-N,N-diethylaminoph
Page 106 and 107: 84 apparatus. The solution was adde
Page 108 and 109: 86 Di-tert-butylisopropylphosphine
Page 110 and 111: 88 13 C NMR: δ = 32.9 (d, J = 12 H
Page 112 and 113: 90 13 C NMR: δ = 41.5 (d, J = 61 H
Page 114 and 115: 31 P NMR: δ = 53.4 ppm. 92 C16H31O
Page 116 and 117: 94 13 C NMR: δ = 40.8 (d, J = 3 Hz
Page 118 and 119: 96 31 P NMR settings: It is known t
Page 120 and 121:
98 Theoretical ratio: (96.1:3.9) Ex
Page 123 and 124:
101 4 The Preparation and Racemate
Page 125 and 126:
103 extraction protocol with ethyl
Page 127 and 128:
105 extracted with ethyl acetate (2
Page 129 and 130:
107 (+)-(M)-Dimethyl-6,6’-dibromo
Page 131 and 132:
109 (+)-(M)-2,2’-Dibromo-6,6’-b
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111 1 H NMR: δ = 7.2 (m, 20 H), 7.
Page 135 and 136:
113 2,2’-Dilithio-6,6’-bis(meth
Page 137:
References
Page 140 and 141:
116 Conference Proceedings, Naples,
Page 142 and 143:
118 [ 70] J. Drowart, C.E. Myers, R
Page 144 and 145:
120 [117] S.T. Graul, R.R. Squires,
Page 146 and 147:
122 [170] B.H. Lipshutz, F. Kayser,
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124 [212] M. Schlosser, in Organome
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O P 27i: p. 30, 80 C 9H 21OP P 26b:
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P P P O 2: p. 11, 59 3 P O O O 11:
Page 160:
Nom Maurin Prénom Michaël 129 Cur
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My PhD dissertation - Institut Fresnel

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