A Route to Carbasugar Analogues - Jonathan Clayden - The ...

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Chapter 3 – Oxazoline synthesis & removal Ph O Ph NH Ph Ph O N H +H 2 O Ph Ph HO N H OH - H + Ph Ph NH OH O + H + - H+ pKa 6 144 231 pKa −2 Ph Ph Ph O N Ph O N H 2 OH 230 232 pKa 10 + H + Ph HO pKa −2 N Ph HO Ph N Ph + H 2 O HO HO Ph NH Ph - H + Ph Ph NH OH O 233 Scheme 3.38 – hydrolysis of oxazolidine, pKa values are approximate in water The research of Bundgaard and Fife both identify the appearance and disappearance of iminium ion 233 during hydrolysis. This is initially surprising since this intermediate must come from protonation of an ether in the presence of an amine. However, this occurs on both hydrolytic pathways, and formation of iminium ion 233 is considerably more favourable than oxonium 231. These equilibria seem to favour the use of acid conditions, and it remains unclear why hydrolysis should be favoured under neutral conditions in the studies of Bundgaard. 127
3.2 – Oxazoline removal 3.2.6 Determination of optical purity Ph Ph O N i) MeOTf, 18 hr then NaBH 4 HO p-BrBzCl DMAP O-pBrBz O 201 ii) Oxalic acid, 3 d rt iii) NaBH 4 OH 225 94% > 95:5 dr Et 3 N, CH 2 Cl 2 O-pBrBz 62% 115 > 99:1 e.r. Scheme 3.39 – determination of optical purity The alkylation-reduction-hydrolysis method was applied to enone 201 and the resulting diol benzoylated to allow HPLC analysis, showing bisbenzoate 115 to be essentially optically pure. The para-bromobenzoate was chosen since it x-ray crystallography would allow confirmation of the absolute stereochemistry, however bisbenzoate 115 could not be crystallised. 128
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Dearomatising Addition of Organolit
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2.3 Synthetic Scope 64 2.3.1 Organo
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Abstract Dearomatising Addition of
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The Author The Author graduated fro
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Abbreviations & Conventions Ac acet
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RDS rate determining step R f RC rt
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Chapter 1: Introduction Chapter 1 -
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Chapter 1: Introduction controlled
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Chapter 1: Introduction diastereome
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Chapter 1: Introduction combine mor
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Chapter 1: Introduction O Ar Cl TMP
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Chapter 1: Introduction conditions,
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Chapter 1: Introduction chiral oxaz
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Chapter 1: Introduction Again a lar
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Chapter 1: Introduction 34 Scheme 1
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Chapter 1: Introduction The amino a
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Chapter 1: Introduction It was envi
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Chapter 1: Introduction COR' i) ATP
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Chapter 1: Introduction O i) ATPH,
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Chapter 1: Introduction 1.4 Nucleop
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Chapter 1: Introduction Unlike the
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Chapter 1: Introduction Diene (-)-8
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Chapter 1: Introduction A scheme su
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Chapter 1: Introduction Cl R + 93 S
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Chapter 2 - Dearomatising additions
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Page 76 and 77: Chapter 2 - Dearomatising additions
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Page 95 and 96: 3.1 - Oxazoline synthesis 3.1.1.a H
Page 97 and 98: 3.1 - Oxazoline synthesis O Ar OH i
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Page 101 and 102: 3.1 - Oxazoline synthesis mCPBA O N
Page 103 and 104: 3.1 - Oxazoline synthesis 3.1.4.b M
Page 105 and 106: 3.1 - Oxazoline synthesis Ph Ph Ph
Page 107 and 108: 3.2 - Oxazoline removal O N O OH 3N
Page 109 and 110: 3.2 - Oxazoline removal O Me O N OM
Page 111 and 112: 3.2 - Oxazoline removal However, th
Page 113 and 114: 3.2 - Oxazoline removal 3.2.3 Reduc
Page 115 and 116: 3.2 - Oxazoline removal Ph O N Ph P
Page 117 and 118: 3.2 - Oxazoline removal 3.2.3.c Ami
Page 119 and 120: 3.2 - Oxazoline removal Ph Ph Ph Ph
Page 121 and 122: 3.2 - Oxazoline removal 3.2.5.b N-A
Page 123 and 124: 3.2 - Oxazoline removal Ph Ph O N H
Page 125: 3.2 - Oxazoline removal Ph Me Ph Me
Page 129 and 130: Better, however, would be a method
Page 131 and 132: 4.1 - Introduction HO OH OH HO OH O
Page 133 and 134: 4.1 - Introduction (-)-Shikimic aci
Page 135 and 136: 4.1 - Introduction followed by Flem
Page 137 and 138: 4.2 - Carbasugar synthesis 4.2 Synt
Page 139 and 140: 4.2 - Carbasugar synthesis stereoce
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Page 143 and 144: 4.2 - Carbasugar synthesis support
Page 145 and 146: 4.2 - Carbasugar synthesis Ox* Ox*
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Page 157 and 158: 4.4 - Revised altrose synthesis 4.4
Page 159 and 160: 4.4 - Revised altrose synthesis suf
Page 161 and 162: 4.4 - Revised altrose synthesis ind
Page 163 and 164: 4.5 - Mannose synthesis 4.5 Synthes
Page 165 and 166: 4.5 - Mannose synthesis It is clear
Page 167 and 168: 4.5 - Mannose synthesis considering
Page 169 and 170: 4.5 - Mannose synthesis which would
Page 171 and 172: 4.5 - Mannose synthesis One clear a
Page 173 and 174: 4.5 - Mannose synthesis 4.5.2.b Epo
Page 175 and 176: 4.5 - Mannose synthesis hydrolysis
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4.5 - Mannose synthesis The second
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4.6 - Summary 4.6 Summary & Future
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4.6 - Summary OH CDI, NH 2 OH.HCl,
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184
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References (37) Rawson, D. J.; Meye
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References (105) Gajewski, J. J.; B
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References (169) McCormick, J. P.;
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References 192
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Experimental section 254nm, dodecam
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Experimental section General Proced
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Experimental for chapter 2 Synthesi
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Experimental for chapter 2 (CDCl 3
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Experimental for chapter 2 3H, OMe
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Experimental for chapter 2 Ph), 139
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Experimental for chapter 2 H4), 5.2
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Experimental for chapter 2 108 R f
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Experimental for chapter 2 Synthesi
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Experimental for chapter 3.1 satura
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Experimental for chapter 3.1 Na 2 S
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Experimental for chapter 3.1 Synthe
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Experimental for chapter 3.1 128.9,
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Experimental for chapter 3.1 Microw
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Experimental for chapter 3.1 R f :
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Experimental for chapter 4.1 281 R
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Experimental for chapter 4.1 combin
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Experimental for chapter 4.1 3H, OB
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Experimental for chapter 4.2 (1S*,2
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Experimental for chapter 4.2 10.0,
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Experimental for chapter 4.2 cm 3 )
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Experimental for chapter 4.2 5.7 Re
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Absolute structure parameter 1.3(11
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_diffrn_standards_interval_time ? _
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H13 H 0.8405 0.7136 -0.0889 0.026 U
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C4 C5 1.454(2) . ? C5 C6 1.324(2) .
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C24 C23 C22 120.0(2) . . ? C24 C23
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. Compound 102c Ph O N Ph Me 102c O
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_diffrn_standards_interval_time ? _
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H11 H 0.8924 0.9592 0.6829 0.022 Ui
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C2 H2 1.0000 . ? C3 C21 1.506(2) .
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C26 C21 C3 121.41(15) . . ? C23 C22
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c. Compound 213 Ph O N Ph Me OH 213
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_cell_volume 1080.9(4) _cell_formul
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_refine_ls_number_reflns 4736 _refi
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H25 H 0.7979 0.2335 0.3365 0.028 Ui
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C4 0.025(4) 0.019(4) 0.018(4) 0.001
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loop_ _geom_bond_atom_site_label_1
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C9 C4 C1 107.1(5) . . ? C10 C4 C1 1
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C36 C38 H38A 109.5 . . ? C36 C38 H3
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C29 C30 C36 C37 -90.4(7) . . . . ?
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The structure was solved by the dir
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_reflns_number_total 2447 _reflns_n
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C7 C 1.1671(4) 0.7629(7) 1.2254(4)
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C3 0.015(3) 0.016(3) 0.021(3) -0.00
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C21 H21A 0.9800 . ? C21 H21B 0.9800
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H21A C21 H21C 109.5 . . ? H21B C21
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