I= SYNTHETIC APPROACHES TO POLY SUBSTITUTED CHIRAL TETRAHYDROFURANS AND CONTROL OF DIASTEROSELECTIVTY BY REMOTE SUBSTITUENTS
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Title of Thesis
SYNTHETIC APPROACHES TO POLY SUBSTITUTED CHIRAL TETRAHYDROFURANS AND CONTROL OF DIASTEROSELECTIVTY BY REMOTE SUBSTITUENTS
Author(s)
Fazila Iqbal
Institute/University/Department Details
University of Karachi./H.E.J. Research Institute of Chemistry
Session
1999
Subject
Chemistry
Number of Pages
161
Keywords (Extracted from title, table of contents and abstract of thesis)
chiral tetrahydrofurans, d-glucose, d-mannose, d-galactose, diastereoselectivity, carbohydrate

Abstract
This thesis is presented in two parts. The Part-A describes the syntheses of polysubstituted chiral tetrahydrofurans from the readily available carbohydrate precursors including D-glucose, D-mannose and D-galactose, respectively.

The Part-B of the thesis describes the control of diastereoselectivity by remote substituents.
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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents/ Summary
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2 1 Part- A :Synthetic Approaches To Polysubtituted Chiral Tetrahydrofurans 6
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  1 Introduction 8
  1.1 Polyether Antibiotics 8
  1.2 8
  1.3 Lasalocid A 9
  1.4 Monensin 9
  1.5 Slinomycin And Narasin 10
  1.6 Norherqirenione 10
  1.7 Septomycin 10
  1.8 Annonaceous Acetogenins 11
  1.9 Annonacin 12
  1.10 Uvaricin 12
  1.11 Goniocin 12
  1.12 C-Glycosides 13
  1.13 Showdomycin 13
  1.14 Citreoviridin 13
  1.15 Gilvocarcin.V 14
  1.16 Previous Synthetic Efforts Towards Polysubstituted Chiral Tetrahyrofurans 15
  1.17 Oxidative Cyclization 15
  1.18 Radical Reaction 22
  1.19 Electrophilic Cyclization 23
  1.20 Preparation From Furan 26
  1.21 Reduction-Cyclization Of Y-Hydroxyketones 28
  1.22 Cyclization Of 1 ,4 -Diols 29
  1.23 Nucleophilic Substitution Of Glycofuranosides 31
  1.24 Miscellaneous Routes 31
3 2 Results And Discussion 34
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4 3 Experimental 50
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  3.1 General Experimental 50
  3.2 Chemicals 50
  3.3 Solvents 50
  3.4 Chromatographic Methods 51
  3.5 Thin Layer Chromatography 51
  3.6 Column Chromatography 51
  3.7 Spray Reagents 51
  3.8 Orcinol 51
  3.9 Ceric Sulphate 51
  3.10 Septroscopic Methods 52
  3.11 Mass Spectrometry 52
  3.12 Infrared Spectrocopy 52
  3.13 NMR Spectroscopy 52
  3.14 UV Spectrometry 52
  3.15 Physical Methods 53
  3.16 Optical Rotations 53
  3.17 Melting Points 53
  3.18 Ental Analysis 53
  3.19 Tion Conditions 53
  3.20 4 ,6 -Tetra-O-Acetyl-A-D-Bromoglucopyranoside (122) 54
  3.21 4 ,6 -Tetra-O-Acetyl-A-D-Bromoglucopyranoside (123) 55
  3.22 Tri-O-Acetyl-D-Glucal (124) 56
  3.23 Tri-O-Acetyl-D-Mannal (124) 57
  3.24 D-Glucal (125) 58
  3.25 D- Mannal (125) 59
  3.26 N-P-Toluenesulfonyl Imidazole (126) 59
  3.27 3 ,6 -Anghydro-4-O-(P- Toluenesulfonyl )-D- Glucal (127) 60
  3.28 (2R ,3R,4R )-2-Hydroxymethyl-3-O-Tosyl-4-Hydroxytetrahydrofuran(128) 61
  3.29 2 ,3,4,6 -Tetra-O-Acetyl-A-D-Bromogalactose (130) 62
  3.30 Tri-O-Acetyl-D-Galactal (131) 64
  3.31 D-Galactal (132) 65
  3.32 (2R ,3R,4R )-2-Hydroxymethyl-3-O-Tosyl-4-Hydroxytetrahydrofuran (134) 67
  3.33 Attempts Towards Displacement Of Tosyloxy Group In Bicyclic 67
  3.34 Compound 127 68
  3.35 Attempted Displacement With Iodid 68
  3.36 Attempted Displacement With Azide 69
  3.37 Preparation Of N-Butyl Bromide 69
  3.38 Preparation Of Dilithium Tetrachlorocuprate (Li2CuCl4) 69
  3.39 Attempted Displacement With N-Butyl Group 69
  3.40 Attempted Displacement With Vinyl Group 70
  3.41 Attempted On Displacement With Malonate Group 71
  3.42 Attempts Towards The Reduction Of Tosyloxy Group Of Bicyclic Compound 127 73
  3.43 Reduction With Nal In The Presence Of Zn Powder 73
  3.44 Reduction With Nabh4 In DMSO 73
  3.45 Reduction With Nabh4 In Ethanol 73
  3.46 Reduction With Liaih4 In Ether 73
  3.47 Reduction With Liaih4 In Tetrahydorfuran 74
  3.48 N-Methanesulfonyl Imidazole (135) 74
  3.49 3 ,6 -Anhydro-4-O-( Methanesulfonyl )-D- Glucal (136) 75
  3.50 Attempts Towards Displacement Of Methanesulfonyloxy Group In Bicyclic Compound 136 76
  3.51 Attempted Displacement With N-Butyl Group 76
  3.52 Attempted Displacement With Iodide 76
  3.53 Trifluoromethanesulfonic Anhydride 76
  3.54 Trifluoromethanesulfonic Imidazole (137) 77
  3.55 3 ,6 -Anhydro-4-O-( Trifluoromethanesulfonyl )D- Glucal (138) 77
  3.56 Attempts Towards The Displacement Of Trifluoromethane-Sulfonyloxy Group Of Bicyclic Compound 138 78
  3.57 Attempted Displacement With Iodide 78
  3.58 Attempted Displacement With Vinyl Group 79
  3.59 Tables 80
5 4 References 94
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6 5 Part- B : Control Of Diastereoselectivity By Remote Substituents 103
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7 6 Results And Discussion 111
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8 7 Experimental 118
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  7.1 General Experimental 118
  7.2 Chemicals 118
  7.3 Solvents 118
  7.4 Chromatographic Methods 118
  7.5 Spray Reagents 119
  7.6 Ceric Suphate 119
  7.7 Spectroscopic Methods 119
  7.8 Physical Methods 119
  7.9 Reaction Conditions 119
  7.10 General Procedure For The Preparation Of 1-Ethynylcycloalkanols (16a-E ) 120
  7.11 1-Ethnylcyclopentanol (17a ) 124
  7.12 1-Ethnylcyclopentanol (17b ) 124
  7.13 1-Ethnylcyclopentanol (17c ) 125
  7.14 1-Ethnylcyclopentanol (17d ) 126
  7.15 1-Ethnylcyclopentanol (17e ) 127
  7.16 General Procedure For The Preparation Of Allylic Alcohols (18a-E ) 127
  7.17 1-Cyclopentene-1-Ethanol (18a ) 128
  7.18 1-Cyclopentene-1-Ethanol (18b ) 128
  7.19 1-Cyclopentene-1-Ethanol (18c ) 129
  7.20 1-Cyclopentene-1-Ethanol (18d ) 130
  7.21 1-Cyclopentene-1-Ethanol (18e ) 131
  7.22 Trimethyl B-( Methoxy ) Orthopropionate (19) 131
  7.23 General Procedure For The Preparation Of Methyl 2-(2-Ethylidenecycloalkyl )- 3-Methoxypropionates (20a-E) 132
  7.24 Methyl 2-(2-Ethylidenecyclohexyl)-3-Nethoxypropionate (20a ) 133
  7.25 Methyl 2-(2-Ethylidenecyclohexyl)-3-Nethoxypropionate (20b ) 134
  7.26 Methyl 2-(2-Ethylidenecyclohexyl)-3-Nethoxypropionate (20c ) 135
  7.27 Methyl 2-(2-Ethylidenecyclohexyl)-3-Nethoxypropionate (20d ) 136
  7.28 Methyl 2-(2-Ethylidenecyclohexyl)-3-Nethoxypropionate (20e ) 137
  7.29 Triethyl Orthoacetate (21) 139
  7.30 General Procedure For The Preparation Of E- Alkylidene Cycloalkanes (22a-E ) 140
  7.31 Ethyl 2-(2-Ethylidenecyclopentyl) Ethanoate (22a ) 140
  7.32 Ethyl 2-(2-Ethylidenecyclopentyl) Ethanoate (22b ) 141
  7.33 Ethyl 2-(2-Ethylidenecyclopentyl) Ethanoate (22c ) 141
  7.34 Ethyl 2-(2-Ethylidenecyclopentyl) Ethanoate (22d ) 142
  7.35 Ethyl 2-(2-Ethylidenecyclopentyl) Ethanoate (22e ) 143
  7.36 Epoxiation Of Compound 20b (23) 144
  7.37 Methyl 2[3B(S*)-2a-Methyl-1- Oxaspiro[ 2.5]Oct-4B-Yl] Propenoate (24) 145
  7.38 General Procedure For The Preparation Of Methyl 2- (2-Ethylidenecycloalkyl) Propenoates (26 ,29 -30) 146
  7.39 Methyl 2-(2-Ethylidenecyclopentyl) Propenoate (29) 146
  7.40 Methyl 2-(2-Ethylidenecyclohexyl) Propenoate (26) 147
  7.41 Methyl 2-(2-Ethylidenecycloheptyl) Propenoate (30) 148
  7.42 Methyl 2-(2-Ethylidenecyclooctyl) Propenoate (29) 149
  7.43 General Procedure For Epoxidation Of Compounds 26 ,29 -31 (25,32-34) 149
  7.44 Methyl 2[3a(R* )2 -B-Methyl-2-Oxapiro[2.4] Hept-4-B-Yl] Propenoate (32) 150
  7.45 Methyl 2[3a(R* )2 -B-Methyl-2-Oxapiro[2.5] Oct-4-B-Yl] Propenoate (25) 150
  7.46 Methyl 2[3a(R* )2 -B-Methyl-2-Oxapiro[2.6] Non-4-B-Yl] Propenoate (33) 151
  7.47 Methyl 2[3a(R* )2 -B-Methyl-2-Oxapiro[2.7] Dec-4-B-Yl] Propenoate (34) 152
  7.48 1B-Ethenyl-2B-[1-Hydroxymethyl) Ethenyl ] Cyclohexanol (35) 152
  7.49 1a-Ethenyl-2B-[1-Hydroxymethyl) Ethenyl ] Cyclohexanol (36) 154
  7.50 Methyl 2-[2-Bromo-2-( Bromoethyl ) ] Propenoate (28) 155
9 8 References 156
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  8.1 List Of Publications 160