feb_05 - 2/5/2010 Sketch the diene and dienophile would...

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Unformatted text preview: 2/5/2010 Sketch the diene and dienophile would give the following cyclohexene? cyclohexene? + heat Which TS leads to the product shown? O O Me H A. endo CO2Me CO2Me CO2CH3 H CO2Me H H = CO2Me H CO2Me CO2Me H CO2Me CO2Me H = H A B + H CO2Me O O B. exo Me 2 C CO2Me D + 1 H Which TS leads to the product shown? O O Sketch the product of the following intramolecular DielsDielsAlder Reaction? Me H + heat H CO2Me CO2Me CO2Me H = H CO2CH3 H H O O Me A O H B C D O H H H 3 4 Sketch the product of the following intramolecular DielsDielsAlder Reaction? + heat Sketch the product of the following intramolecular DielsDielsAlder Reaction? + heat A O H B C D A O H B C O H D 5 6 1 2/5/2010 Is it possible to control the reaction conditions so that one of these enantiomers is the major product? + heat Is it possible to control the reaction conditions so that one of these enantiomers is the major product? + heat TfO TfO N H a lewis acid lewis B Ar H N Lewis acids catalyze the DielsDiels-Alder reaction. Why? Why? O H H O H + H O H B Ar O + H H H O + H H + O enantiomers 7 enantiomers 8 Is it possible to control the reaction conditions so that one of these enantiomers is the major product? + heat Predict the product of the following reaction. CH3 CH3 H O O H TfO H Ar Ar B Ar N H chiral lewis acid catalysts can give one enantiomer as the the major product. H H H O + H O H H CHC 3 H H + -78°, 13h O CH3 H H O C H H CH3 O H CH3 O H CH3 O H CH3 H O + major product! enantiomers 9 A B C D 10 Predict the product of the following reaction. TfO H Ar Ar B Ar What reactant would be necessary for the following Diels-Alder reaction. H CH3 O CH3 + CH3 H N O ? H -78°, 13h 96% yield 97% ee 11 A B C D 12 2 2/5/2010 Why doesn't cyclooctatetraene react in the Diels-Alder reaction? What is the structure of compound A? 0.01% 0.01% A 99.99% 99.99% + 13 14 How does cyclobutadiene react to give cyclooctatetraene? 0.01% + 99.99% 15 16 H H H O O O n H H H pol carbonate ly benzene 17 18 3 2/5/2010 O O OH CH3 O O CH3 O H3C O CH3 O NH2 methyl salicylate dopamine myristicin wintergreen oil of wintergreen 19 nutmeg 20 Are aromatics such as benzene very reactive? 7 HO Br HO H H Br Br2 Br2 FeBr3 Br + H Br urishinol 21 22 Does benzene have a “special” stabilization that would not be anticipated for a compound containing three double bonds? How could the resonance energy (aromaticity) of benzene be estimated? C6H6 unreactive, stable C6H6 reactive, unstable -208.4 kJ mol H2/Pd energy 23 24 4 2/5/2010 How could the resonance energy (aromaticity) of benzene be estimated? What is the resonance energy (aromaticity) of benzene? resonance energy = -150.6 kJ real mol hypothetical -119.7 kJ mol H2/Pd -119.7 kJ mol -208.4 kJ mol -119.7 kJ mol H2/Pd -208.4 kJ mol -119.7 kJ mol H2/Pd -359 kJ mol -119.7 kJ mol H2/Pd H2/Pd H2/Pd H2/Pd energy 25 energy 26 What is the structure of benzene? What is the structure of benzene? Br Br August Kekulé 1872 August Kekulé 1872 Kathleen Lonsdale 1929 27 28 What theories explain benzene's stability? Which of these models predicts the shortest carbon-carbon bonds? August Kekulé 1872 (A) 1872 147 pm 135 pm Edwin Schrödinger 1926 (B) 1926 ~ 140 pm 29 30 5 ...
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