My PhD dissertation - Institut Fresnel

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28 Furthermore, the intensities of all signals were directly proportional to the amount of each product present in the mixture, which allowed direct determination of the k1/2 values with respect to the internal standard used. In order to get accurate results and devoid of any artifact, the 31 P NMR spectra were recorded in a nondecoupling mode since it is known that the Nuclear Overhauser Effect (NOE) causes changes in the peak intensities during the 1 H decoupling process [ ] 141 . On the other hand, for the peak intensities to be effectively relevant to the exact amount of each product quantified, the 31 P nucleus relaxation time (T1) had to be determined and set by classical NMR techniques so that all considered nuclei went back to equilibrium. Under these conditions, the 31 P NMR analysis could afford accurate and quantitative results. To determine the standard deviation on each measurement, a series of phosphine oxide pairs were prepared in different extreme ratios (ranging from 1 : 1 until 99 : 1) by accurately weighting the substances. 31 P NMR analyses of each of these mixtures in the above mentioned conditions revealed an average standard deviation of 0.5% (see Experimental Part). Quantitative 31 P NMR analysis technique has been extensively used during the last two decades for enantiomeric excess (ee) determinations of chiral alcohols, diols and amines using phosphorus chiral derivatization agents (CDA) [ - ] 142 146 . B.L. Feringa et al. [143, 145] and A. Alexakis et al. [142, 144, 146] reported average incertitudes on the measure in good agreement with those determined in this study when using this technique of quantification. Finally, for the sake of testing the reproducibility of the results, the data reported for each phosphonium halide were measured as an average of three separate runs carried out in the same experimental conditions. 3.3.4 Starting Materials and Reference Substances For the determination of relative alkyl anions stabilities, all the starting mixed tetraalkylphosphonium halides had to be prepared by quaternarization of the corresponding tertiary alkylphosphines with the appropriate alkyl halide. On the other hand, all the phosphine oxides which could possibly form during alkaline decomposition reactions also had to be prepared to serve as authentic reference compounds for 31 P NMR assignment. These oxides were in most cases, synthesized by simple oxidation of the tertiary phosphine already prepared.
29 To prepare tertiary phosphines bearing two different types of alkyl substituents, the choice of dichloro-N,N-diethylaminophosphine [ ] 147 as starting material was found to be the most judicious. As a matter of fact, the use of organometallic reagents to selectively substitute one or two chlorine atoms from phosphorus trichloride resulted, in most cases, in a mixture of mono-, di- and trisubstituted phosphines. On the contrary, at low temperature it was possible to treat dichloro-N,N-diethylaminophosphine with two equivalents of an alkyllithium or alkylmagnesium reagent without any P-N bond cleavage, affording a series of dialkyl-N,N-diethylaminophosphines 24a - 24d with moderate to excellent yield (Table 2). PCl 3 HNEt 2, DEE - 75 °C to 25 °C Cl P N Cl 23, 85% RLi or RMgX - 75 °C R P N R 24a - 24d Table 2. Dialkyl-N,N-diethylaminophosphines R2PN(C2H5)2. Product R = RLi or RMgX Yield 24a -C(CH3)3 LiC(CH3)3 89% [ ] 148 24b -C4H9 LiC4H9 88% [147] 24c -C2H5 H5C2MgBr 81% [147] 24d -CH3 LiCH3 49% Each dialkyl-N,N-diethylaminophosphine of the series 24a - 24d was then converted to the corresponding chlorophosphines 25a - 25d using a novel efficient method. Treatment of phosphines 24a - 24d with a 4.8 M hydrogen chloride solution in diethyl ether rather than with gaseous hydrogen chloride [147] gave dialkylchlorophosphines 25a - 25d with better yields (Table 3) and a more convenient work up procedure. Other attempts to prepare 25a - 25d from aminophosphine 23 in a one pot synthesis gave comparable overall yields, without isolation of the intermediate dialkylaminophosphines 24a - 24d. [ ] 149
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: 27 However, in the eventuality of a
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 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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My PhD dissertation - Institut Fresnel

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