Advances in the stereoselective synthesis of antifungal agents and ...

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Chapter 6 147RR[P(Ph) 3 ]Pd°OHOPh 3 PPh 3 PPdROHPh 3 PPh 3 P2+PdHROScheme 6.17: Pd° catalysis in the heteroannulation step.An easier explanation could involve a simple base catalyzed 5-endotrig cyclization favoured by the Baldwin rules (scheme 6.18).RROH+BASEO - +H + B -ORScheme 6.18: base catalyzed cyclization to benzofuran.The first hypothesis involving the coordination of the triple bondfrom Pd° would implicate a double palladium catalytic cycle, whereas thesecond hypothesis implicates a single Pd° catalytic cycle and a basiccyclization to the final product. In order to shine more light on themechanism in the next paragraphs studies to elucidate further themechanism are described.6.6.1. Cyclization studies.For this 2-iodophenol was first acetylated with acetyl chloride indichloromethane and then coupled under palladium catalysis with racemic
Chapter 6 1481-phenyl-2-propyn-1-ol (±)-58a to form the compound (±)-71(Scheme6.19)OHIAcCl; TEA;IPdCl 2 [P(Ph 3 ) 2 ];CuIOHCH 2 Cl 2OAcTMG; 40°; ArOAc(±)-71Schem 6.19: Synthesis of (±)-71.In an attempt to deprotect the acetyl group in (±)-71 using asaturated solution of K 2 CO 3 in absolute methanol at 0°C led to theracemic aryl-benzo[b]furan carbinol (±)-27g (Scheme 6.20).OHOAcK 2 CO 3 , MeOH(±)-71 (±)-27gOOHScheme 6.20: synthesis of (±)-27g by 5-endotrig base catalized cyclization.The formation of (±)-27g under these reaction condition provedthat the 5-endo trig cyclization can occur in these substrates.The unprotected analogue of (±)-71, e.i.(±)-62 had already beenobtained in 60 % yield as side product of the Pd catalyzed cyclizationwhen only 1% of catalyst was used (entry 4, Table 6.4). In order toimprove the chemical yield it was enough to use only one equivalent ofbase. This way (±)-62 was obtained in 89.5% chemical yield (scheme6.21).(±)-62 can be considered a key intermediate for studying themechanism involved in the second part of the reaction, e.i. for thesynthesis of benzofuranes or indoles.
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Advances in the stereoselectivesynt
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ACKNOWLEDGMENT:I would like to than
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Summary:Numerous drugs are chiral,
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IndexII2.2 Synthesis of enantiopure
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IndexIV4.4. Stereochemical Assignme
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IndexVImethyl amine 69 1446.6. Stud
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IndexVIII8.23.3.1 Desilylation usin
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Chapter 1 11.Introduction1.1. Chira
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Chapter 1 3The concept of stereoche
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Chapter 1 5switches is in the area
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Chapter 1 7-bonds 9 . It is now wid
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Chapter 1 914CH 3Cyt P-450 DMOH3O 2
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Chapter 1 11piperazine) is also the
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Chapter 1 13The four stereoisomers
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Chapter 1 15single enantiomers and
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Chapter 1 17was synthesized by the
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Chapter 1 19HOHODesmolaseHOCholeste
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Chapter 1 21formic acid results in
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Chapter 1 23inactivation. 113 . Bec
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Chapter 1 25Two newer compounds whi
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Chapter 1 2715 is an advanced repre
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Chapter 1 29transformation of the a
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Chapter 1 31Enantioselective synthe
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Chapter 1 33+R,S DRUG ANCHOR R MOLE
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Chapter 1 35solubilized in hot etha
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Chapter 2 37RsORmRmRsRLRL RRRLH - A
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Chapter 2 39The stereochemistry and
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Chapter 2 41An asymmetric reducing
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Chapter 2 43This approach clearly e
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Chapter 2 45PhaxeqP 1MP 2axeqPhP 2M
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Chapter 2 47pyrrolidine ] 20 , LAH-
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Chapter 2 49Enzymatic reactions are
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Chapter 2 51As [ES] in equation 4 c
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Chapter 2 53E+AK 1AK -1AEAK 2AE+PE+
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Chapter 2 552.2.4 Lipases.Most lipa
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Chapter 2 57enzyme intermediate can
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Chapter 2 59projecting above the pl
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Chapter 2 612.3.1.1. Step 1: Adduct
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Chapter 2 63A -+ ROHRO - + AH'RO 2
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Chapter 2 65There are various effec
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Chapter 2 67The reactions were foun
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Chapter 2 69Yamanaka and coworkers
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Chapter 2 71sodium or potassium car
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Chapter 3 73The reaction is quite s
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Chapter 3 75literature as the best
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Chapter 3 77dry solvents and, is ch
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Chapter 3 79XXOH+ H 2 NDry K 2 CO 3
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Chapter 3 81substituents are the mo
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Chapter 3 83induces a rotation of t
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Chapter 3 85very sharp and it was p
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Chapter 3 87Raney NickelOH Br MeOH;
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Chapter 4 8933a-m were hydrolysed t
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Chapter 4 91benzo[b]furane (entries
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Chapter 4 93hydroxy or amine groups
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Chapter 4 95the products with ethyl
Page 112 and 113: Chapter 4 97NCO 2 HNCO 2 H(±)34c(-
Page 114 and 115: Chapter 4 99NNH37CO2EtOH(±)-27a(+)
Page 116 and 117: Chapter 4 101As already outlined ab
Page 118 and 119: Chapter 4 103(+)-(S)-2-octylimidazo
Page 120 and 121: Chapter 4 105CNNH N2 NCN nC 6 H 13N
Page 122 and 123: Chapter 4 107key step is the conver
Page 124 and 125: Chapter 4 109reverse addition in th
Page 126 and 127: Chapter 4 111which was eliminated e
Page 128 and 129: Chapter 4 113separate (±)-57a and
Page 130 and 131: Chapter 5 115to avoid this side rea
Page 132 and 133: Chapter 5 117Complete degradation o
Page 134 and 135: Chapter 5 119Entry R T °C Product
Page 136 and 137: Chapter 5 1212:1:3 in weight. All t
Page 138 and 139: Chapter 5 123reaction conditions we
Page 140 and 141: Chapter 5 125Entry Substrate R Time
Page 142 and 143: Chapter 5 127experiments. But it wa
Page 144 and 145: Chapter 5 129OClOSAM IIPH=7; R.T.OH
Page 146 and 147: Chapter 5 131OHOXHOHRHK 2 CO 3 ; Me
Page 148 and 149: Chapter 6 133HCuSO 4 .5H 2 O,NH 4 O
Page 150 and 151: Chapter 6 1356.2.1 Heteroannullatio
Page 152 and 153: Chapter 6 137This discovery allowed
Page 154 and 155: Chapter 6 139OH(±)-62OHFigure 6.1
Page 156 and 157: Chapter 6 141Entry Substrate R Time
Page 158 and 159: Chapter 6 143HOH58-a-c,e,h-lRPdCl 2
Page 160 and 161: Chapter 6 145afforded the benzo[b]f
Page 164 and 165: Chapter 6 149H2-IodophenolOHOH(±)-
Page 166 and 167: Chapter 6 151presence of base as de
Page 168 and 169: Chapter 7 153A chiral lithium alumi
Page 170 and 171: Chapter 7 155derivatives were tried
Page 172 and 173: Chapter 7 157Finally an hypothesis
Page 174 and 175: Chapter 8 159were washed with a sat
Page 176 and 177: Chapter 8 16145 min, the mixture wa
Page 178 and 179: Chapter 8 1638.9 Decarboxylation of
Page 180 and 181: Chapter 8 165Alcohol 27a (0.2 mmol)
Page 182 and 183: Chapter 8 167for 48 h. After coolin
Page 184 and 185: Chapter 8 169room temperature for t
Page 186 and 187: Chapter 8 171in CH 2 Cl 2 and washe
Page 188 and 189: Chapter 8 1738.26 Screening of lipa
Page 190 and 191: Chapter 8 175Na 2 SO 4 . After remo
Page 192 and 193: Chapter 8 177NMR and MS analysis we
Page 194 and 195: Chapter 8 179Argon was bubbled thru
Page 196 and 197: Chapter 8 181IR (CHCl 3 ): ν cm-1=
Page 198 and 199: Chapter 8 183GC-MS: 305 M + (68%),
Page 200 and 201: Chapter 8 185[α] 20 D -5.7 (c 1.75
Page 202 and 203: Chapter 8 187Synthetic method 7.7.1
Page 204 and 205: Chapter 8 189(R,S)-(±)-1-(2-Octyl)
Page 206 and 207: Chapter 8 191M.P. = oil.Elementary
Page 208 and 209: Chapter 8 193Synthetic method 7.11.
Page 210 and 211: Chapter 8 195(±)-N-1-(2-Octyl)-2-t
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Chapter 8 197IR (CHCl 3 ) ν cm-1 =
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Chapter 8 199(±)-1-(4-Fluorophenyl
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Chapter 8 201Physical and spectral
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Chapter 8 203(±)-1-(Phenyl)-2-prop
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Chapter 8 205128.61, 128.87, 130.39
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Chapter 8 207min.Physical and spect
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Chapter 8 20913C J MOD NMR (CDCl 3
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Chapter 8 211(±)-2'-Methylphenyl-2
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Chapter 9 213References chapter 1:1
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Chapter 9 21531) De Felice, R.; Joh
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Chapter 9 21768) Brodie, A.M.H. in
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Chapter 9 219112) Brodie, A. M. H.;
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Chapter 9 2214) Karabatsos, M.C. J.
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Chapter 9 22334c) Blow D. Nature 19
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Chapter 9 22567a) Kundu, N.G.; Pal,
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Chapter 9 22712) Thompson,A.S.; Hum
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