My PhD dissertation - Institut Fresnel

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44 bulk of the O-substituents. Thus, several phenol ether derivatives were prepared from each pure enantiomeric form of biphenol 31. First of all, substrate 31 was converted to the corresponding bis(methoxymethoxy) derivative 34 with 94% yield, using chloromethyl methyl ether [ ] 186 . The methoxymethoxy group had the advantage to tolerate the strongly basic conditions applied during bromine/lithium permutations process with organolithium reagents. It could also be later used as diastereotopic probe for dynamic 1 H-NMR experiments (see § 4.4.1). Br Br OH OH (P)-(-)-31 1) NaH (2.0 eq.), THF, 25 °C 2) CH 3OCH 2Cl (2.0 eq.), 0 °C Br O O Br O O (P)-(-)-34, 94% Enantiomerically pure (M)- and (P)-biphenol 31 were also converted to methyl phenol ether 35 and ethyl phenol ether 36. The former was prepared by subsequent treatment the biphenol 31 with two equivalents of potassium hydroxide and excess of iodomethane in dimethylsulfoxide at ambient temperature. This simple procedure afforded analytically pure 2,2’-dibromo-6,6’-dimethoxybiphenyl (35) in 90% yield without requiring any purification since the product spontaneously crystallized from the reaction mixture. Br Br OH OH DMSO, KOH CH3I, 25 °C Br Br O O (P)-(-)-31 (P)-(-)-35, 90% Afterwards, this bisphenol ether was subjected to bromine/lithium permutation and subsequent treatment with chlorodiphenylphosphine to lead to MeO-BIPHEP via an alternative route to that proposed by R. Schmid et al. [16] . Furthermore, since the nature of the phosphorus substituents is known to play a role, not only on the steric bulk, but also on the electronic properties of the ligands by changing the phosphine basicity, dibromobiphenyl 7 could also be an advantageous precursor for the preparation of a series of "BIPHEP-type" bisphosphines. For example, using various chlorodialkyl- or chlorodiarylphosphines as electrophiles, the transient 6,6'-dilithio-2,2'-dimethoxybiphenyl could possibly be converted into several of modified biphenylbisphosphines.
45 The second phenol ether 36 was finally prepared in a different way than its homologue 35 since the former procedure only afforded moderate yields (56%). Thus, biphenol 31 was first deprotonated in tetrahydrofuran using sodium hydride at 25 °C, and then treated with an excess of ethyl bromide to form 2,2’-dibromo-6,6’-diethoxybiphenyl (36) in 92% yield. Br Br OH OH 1) NaH (2. 0 eq.), THF, 25 °C 2) C2H 5Br (2.0 eq.) Br Br O O (P)-(-)-31 (P)-(-)-36, 92% 4.2 Preparation of Enantiomerically Pure 6,6’-Dibromobiphenyl- 2,2’-dicarboxylic Acid and Derivatives Thereof Following the strategy outlined previously, diacid 37 was prepared, starting from the key intermediate tetrabromobiphenyl 30. The diacid was then resolved into both pure axial enantiomers and reduced to the corresponding bishydromethyl derivative. Although numerous ortho,ortho'-diphenic acids have been reported still to be found on a trial-and-error basis. [ ] 187 , the most suitable resolution method has 4.2.1 Racemic 6,6’-Dibromobiphenyl-2,2’-dicarboxylic Acid Biphenol 30 was treated with two equivalents of butyllithium in tetrahydrofuran at -75°C to produce 2,2'-dibromo-6,6'-dilithiobiphenyl. Subsequent trapping with carbon dioxide and neutralization afforded 6,6’-dibromobiphenyl-2,2’-dicarboxylic acid (37) in 90% yield. Br Br Br Br 30 LiC 4H 9 (2.0 eq.) THF, - 75 °C Br Li Br Li 1) CO 2, THF 2) HCl 10% Br COOH Br COOH rac-37, 90%
Page 1:
Various Facets of Organophosphorus
Page 5:
III Remerciements Je tiens à remer
Page 9:
3.3.6 Relevance of the Data Assesse
Page 13: VII Literature References 115 Compo
Page 17: 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: 43 Few other attempts to selectivel
Page 67 and 68: 47 The enantiomeric purity was chec
Page 69 and 70: 49 A second purpose of this derivat
Page 71 and 72: 51 substrates considered. In conseq
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
Page 133 and 134:
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,
Page 148:
124 [212] M. Schlosser, in Organome
Page 152:
O P 27i: p. 30, 80 C 9H 21OP P 26b:
Page 156:
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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