CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

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IV.5: SSYNTHESSIISS OFF trraannss- t -OAK LACTONE IV.5.1: Introduction The 4,5-disubstituted γ-lactone units are often observed in many variety of biologically relevant molecules. Two of them, the 4S,5R-(trans) and 4S,5S-(cis) isomers of 5-n-butyl-4-methyl-4,5-dihydro-2(3H)-furanone (VII and VIII) (Fig. IV.5.1), also known as ‘oak lactone’ or ‘whisky lactone’, are natural oak components, extracted into wine and spirits during oak barrel maturation. 171 The aroma of alcoholic beverages is believed to be due to the presence of a pure enantiomer of these lactones. The cis- and transconfigurations of the methyl and butyl groups have been determined by 1 H NMR spectroscopy, and the absolute configurations were assigned on the basis of an empirical correlation. 172 Hence, development of strategies to prepare VII and VIII can also be useful towards the synthesis of other biomolecules possessing a similar γ-lactone moiety. C 4 H 9 O O C 4 H 9 O O trans-Oak lactone (VII) cis-Oak lactone (VIII) Fig. IV.5.1. Structure of cis- and trans-Oak lactones. IV.5.2: Previous syntheses So far, several approaches for the synthesis of VII and VIII have been reported. 173 In one of the early synthesis, 173b trans-oak lactone (VII) was prepared using asymmetric enzymatic reduction of ketones. Suzuki et al. 173d synthesized VII starting from the chiral bicyclic lactone (+)-167, prepared from D-mannitol. Nucleophilic addition of n-BuLi to 177
167 and subsequent reduction gave 168. A tetra-n-propylammonium perruthenate (TPAP) catalyzed oxidation of 168 in the presence of 4- methylmorpholine N-oxide (NMO) gave the diastereomeric lactone 169. This on retro-Diels–Alder reaction in refluxing o- dichlorobenzene (ODCB) gave enantiomeric gave the 4-substituted butenolide (−)-170. Finally, stereoselective 1,4-addition of dimethylcuprate furnished VII (Scheme IV.5.1). O i-ii iii C 4 H 9 iv C 4 H 9 O OH O O HO O 167 168 169 170 C 4 H 9 H v VII (i) n-BuLi, toluene, -78 o C; (ii) L-Selectride ® , toluene, -78 o C; (iii) Cat. TPAP, NMO, molecular sieves, CH 2 Cl 2 , 25 o C; (iv) ODCB, Δ; (v) MeLi, CuI, Et 2 O, -78 o C. Scheme IV.5.1 More recently, 173e the Li-enolate of the succinate 171 derived from D-mannitol was reacted with n-pentanal to afford 172 as the major isomer. Its acid-catalyzed deketalisation followed by periodate cleavage of the resulting diol produced a 1:1 anomeric mixture of the lactol 173, which on O-methylation and LiAlH 4 reduction gave the alcohol 174. Its tosylation followed by reduction produced compound 175. Deacetalization of 175 followed by RuO 4 oxidation gave the lactone acid 176, which on decarboxylation under heating produced VII (Scheme IV.5.2). 178
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ASYMMETRIC STRATEGIES FOR THE SYNTH
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ACKNOWLEDGEMENTS First of all, I wa
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CONTENTS SYNOPSIS LIST OF FIGURES L
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SYNOPSIS
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models (e. g. Cram’s model, Felki
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4 1d 4-(CH 3 ) 2 CH-C 6 H 4 1 : 1.5
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14. 1n C 6 H 5 CO C 6 H 5 2n 8 77 1
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imetallic systems. In all the cases
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For the benzylation reaction, the c
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O O 3 CHO i O O + OH 13a O O OH O O
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10 3.5 Ga (2.5) THF KI+LiCl 10 55 5
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multidrug-resistant (MDR) cancer ce
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directly afforded the furanose, whi
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References 1. Stephenson, G. R. Adv
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LIST OF FIGURES
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II.3.13 III.1.1 III.1.2 III.1.3 III
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IV.5.2 IV.5.3 IV.5.4 IV.5.5 1 H NMR
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Table Title Page No. II.3.1 II.3.2
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II. .11 PPREAMBLE Demand for specia
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II. .22 IINTRODUCTIION TO CHIIRALII
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The most dramatic example in this a
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H H 2 N OH COOH i PhH 2 CO O H N H
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Methods of Asymmetric Synthesis: 15
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O O O O i, ii iii iv HO HO N N OH O
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Models for Asymmetric Synthesis. 21
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If a strongly electronegative group
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enantiomeric products are formed at
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vi) The balance between chiral auxi
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IIII. .11 IINTRODUCTIION TO CHIIRAL
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Scheme II.1.2 However, availability
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Prof. R. Noyori received the Nobel
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Apart from the cinchona alkaloids,
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ligand, it assumes a tetrahedral co
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Marshall. 53 More recently, Barbero
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Various protocols have been develop
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In the absence of a sterically-bulk
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IIII. .33. . PPRESSENT WORK It is w
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[pyridinium][Sn 2 Cl 5 ] etc. can b
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RCHO 59a-j i R OH 60a-j (i) Allyl b
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Fig. II.3.2. 1 H NMR spectrum of 60
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in [bmim][BF 4 ] using sub-stoichio
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The reaction in THF was also follow
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The integration of the signal at δ
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The standard reduction potential of
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It has also been reported, 83a,b th
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IIII. .33. .33 Gaal lliuum meeddi i
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5 3.0 5.0 THF LiCl+KI c 14 d 71 6 1
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3 59d 4-(CH 3 ) 2 CH-C 6 H 4 H 60d
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Fig. II.3.8. 13 C NMR spectrum of 6
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Fig. II.3.10. 13 C NMR spectrum of
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fragmentation peak at m/z 138 (19%)
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Fig. II.3.13. 13 C NMR spectrum of
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active catalyst, as suggested for t
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1-(4-Bromophenyl)-but-3-en-1-ol 59b
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1H), 7.90-7.93 (m, 1H); 13 C NMR:
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662, 980, 1079, 1332, 1374 cm -1 .
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IIIIII. .11 DIIASSTEREOSSELECTIIVE
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cyclohexylideneglyceraldehyde (1) 3
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mixture of Zn dust, allyl or γ-sub
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Fig. III.1.2. 13 C NMR spectrum of
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Reaction with crotyl bromide: In ca
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Fig. III.1.5. 1 H NMR spectrum of 6
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The formation of the 2,3-anti addit
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To establish the C-4 configuration
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Allylation with (E) and (Z)-1-bromo
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(i) Zn, aqueous satd. NH 4 Cl, THF,
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Fig. III.1.12. 1 H NMR spectrum of
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Allylation with 1-Bromo-4-(tert)-bu
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fast and gave a significantly bette
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espectively) due to the cyclohexyli
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was treated with excess amount of b
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Fig. III.1.20. 1 H NMR spectrum of
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stereochemistry of allylation of β
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of the products were modest (48-62%
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6 1.2 In (2.0) H 2 O LiCl+ KI 14 72
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are consistent with our previous re
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III.3 EXPERIMENTAL SECTION: General
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(2R,3R)-1,2-Cyclohexylidenedioxy-5-
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for an additional 2 h, gradually br
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(m, 2H), 5.82-5.98 (m, 1H), 7.25-7.
Page 169 and 170: 31.6, 32.2, 63.4, 128.8, 133.0. Ana
Page 171 and 172: 23 (2R,3S,4R)-1,2-Cyclohexylidenedi
Page 173 and 174: (2R,3S,4S)-1,2-Cyclohexylidenedioxy
Page 175 and 176: (m, 1H), 3.50-4.02 (m, 5H), 4.10-4.
Page 177 and 178: and dried. Removal of solvent in va
Page 179 and 180: ine, and dried. Solvent removal und
Page 181 and 182: IIV. .11 SSYNTHESSIISS OFF ENANTIIO
Page 183 and 184: Scheme IV.1.1 The same group also d
Page 185 and 186: IV.1.3: Present work Although sever
Page 187 and 188: O O C 6 H 13 i O C 6 H 13 ii OH C 6
Page 189 and 190: Fig. IV.1.4. 1 H NMR spectrum of 10
Page 191 and 192: the unit-C contribute positively to
Page 193 and 194: tartrate, Ti(O-i-Pr) 4 , CH 2 Cl 2
Page 195 and 196: Based on this hypothesis, the alcoh
Page 197 and 198: OR 3 O R 1 R 2 NaBH 4 H H R 1 R 1 +
Page 199 and 200: (OH). Oxidative cleavage of its α-
Page 205 and 206: IIV. .33: : SSYNTHESSIISS OFF 33' '
Page 207 and 208: For the actual synthesis, (Scheme I
Page 211 and 212: IV.4: SSYNTHESSIISS OFF 22( (SS) )-
Page 213 and 214: (i) PhCHO, triethyl orthoformate, M
Page 215 and 216: O N 3 II Ph HO OH b1 N 3 Ph O O Ben
Page 219: Thus, easily accessible 1 has been
Page 223 and 224: from the appearance of 13 C NMR pea
Page 227 and 228: IV.6 EXPERIMENTAL SECTION (2R,3S,4R
Page 229 and 230: As described earlier, compound 108
Page 231 and 232: 19.5, 23.8, 23.9, 25.1, 26.9, 34.6,
Page 233 and 234: 74.2, 74.4, 110.1, 116.7, 127.6, 12
Page 235 and 236: mmol) in MeOH (10 mL), work up, fol
Page 237 and 238: 7.51 (m, 3H), 7.92-8.08 (m, 2H); 13
Page 239 and 240: subsequent isolation afforded rotam
Page 241 and 242: 4.18 (t, J = 3.4 Hz, 1H), 4.75-4.84
Page 243 and 244: -4.21 (c 1.2, CHCl 3 ); IR: 3466, 1
Page 245 and 246: (3R)- 3,4-O-Cyclohexylidene-2-oxo-1
Page 247 and 248: Water and EtOAc was added to the mi
Page 249 and 250: 24 179. Yield: 1.49 g (77.5%); colo
Page 251 and 252: 24 furnished pure 183. Yield: 0.37
Page 253 and 254: 1. Wender, P. A. Chem. Rev. 1996, 9
Page 255 and 256: 17. Hanessian, S.; Maji, D. K.; Gov
Page 257 and 258: 32. For some selective references s
Page 259 and 260: 43. (a) Cleare, M. J.; Hydes, P. C.
Page 261 and 262: 54. Barbero, A.; Pulido, F. J.; Rin
Page 263 and 264: 2008, 1681. (d) Fargeas, V.; Zammat
Page 265 and 266: 72. Karodia, N.; Guise, S.; Newland
Page 267 and 268: Kaminski, J.; Millhauser, G.; Ortiz
Page 269 and 270: Böhm, V. P. W.; Reisinger, C. J. O
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119. Wender, P. A.; Holt, D. A.; Si
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140. (a) Chemler, S. R.; Roush, W.
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Lett. 1996, 107, 53. (c) Smith, C.
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158. Mitsuya, H.; Weinhold, K. J.;
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L.; Zugay, J. A. J. Med. Chem. 1993
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1. Goswami, D.; Chattopadhyay, A.;
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