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

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Chapter 4 – Synthesis of carbasugars O Me Me i) H - HO HO O O O CO 2 OH 213 328 OH ii) H 2 O HO OH α-L-Mannose analogue 329 OH Scheme 4.45 – proposed reduction-hydrolysis of lactone 213 4.5.1.a Initial studies of lactonisation-epoxidation strategy It was anticipated that lactonisation could be induced under similar conditions to those found before (section 4.2.8), but that replacing the reductive quench with an aqueous one might increase yield of lactone and return some starting material. As before, the alkylation was left overnight, but instead of the standard methanol/THF-borohydrdride quench, aqueous ammonium chloride was added to the reagents in dichloromethane with vigorous stirring. Ox* i) MeOTf, CH 2 Cl 2 16 hr O OH ii) NH 4 Cl (aq) O 8 hr OH 213 328 OH 36 % 97% conv. Scheme 4.46 – lactonisation Lactone 328 was isolated in a similar quantity to the previous conditions, and despite complete conversion of the oxazoline, no other products could be identified before or after purification. That similar amounts of lactonisation were seen under reductive and aqueous quenches lends support to the conclusion that lactonisation occurs during alkylation. Epoxidation of the resulting olefin went cleanly with no other products visible in the crude NMR (Scheme 4.47). There was, however, a striking difference between the carbon NMR of this compound and its diastereomer 307; the carbonyl of the latter was only observable with a relaxation time of 25 seconds, whilst the carbonyl of 329 was observable with a standard relaxation time of 1 second. Since spin relaxation of 13 C nuclei is assisted by nearby protons in a through-space interaction, this is explained by 167
4.5 – Mannose synthesis considering the local environment in the two compounds. In lactone 329 methine H6 is close to the carbonyl, whilst the diastereomeric lactone has no such available proton to assist relaxation; further confirming the stereochemistry of the two compounds. 5s< T 1
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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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3.1 - Oxazoline synthesis 3.1.1.a H
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3.1 - Oxazoline synthesis O Ar OH i
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3.1 - Oxazoline synthesis 3.1.2 Gen
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3.1 - Oxazoline synthesis mCPBA O N
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3.1 - Oxazoline synthesis 3.1.4.b M
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3.1 - Oxazoline synthesis Ph Ph Ph
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3.2 - Oxazoline removal O N O OH 3N
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3.2 - Oxazoline removal O Me O N OM
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3.2 - Oxazoline removal However, th
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3.2 - Oxazoline removal 3.2.3 Reduc
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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 and 126: 3.2 - Oxazoline removal Ph Me Ph Me
Page 127 and 128: 3.2 - Oxazoline removal 3.2.6 Deter
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
Page 141 and 142: 4.2 - Carbasugar synthesis of the o
Page 143 and 144: 4.2 - Carbasugar synthesis support
Page 145 and 146: 4.2 - Carbasugar synthesis Ox* Ox*
Page 151 and 152: 4.2 - Carbasugar synthesis OsO 4 (c
Page 153 and 154: 4.2 - Carbasugar synthesis taken on
Page 155 and 156: 4.2 - Carbasugar synthesis As well
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: 4.5 - Mannose synthesis It is clear
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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
Page 177 and 178: 4.5 - Mannose synthesis The second
Page 179 and 180: 4.6 - Summary 4.6 Summary & Future
Page 181 and 182: 4.6 - Summary OH CDI, NH 2 OH.HCl,
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Page 185 and 186: References (37) Rawson, D. J.; Meye
Page 187 and 188: References (105) Gajewski, J. J.; B
Page 189 and 190: References (169) McCormick, J. P.;
Page 191 and 192: References 192
Page 193 and 194: Experimental section 254nm, dodecam
Page 195 and 196: Experimental section General Proced
Page 197 and 198: Experimental for chapter 2 Synthesi
Page 199 and 200: Experimental for chapter 2 (CDCl 3
Page 201 and 202: Experimental for chapter 2 3H, OMe
Page 203 and 204: Experimental for chapter 2 Ph), 139
Page 205 and 206: Experimental for chapter 2 H4), 5.2
Page 207 and 208: Experimental for chapter 2 108 R f
Page 209 and 210: Experimental for chapter 2 Synthesi
Page 211 and 212: Experimental for chapter 3.1 satura
Page 213 and 214: 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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