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Published byCasey Wright Modified over 2 years ago

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Stereochemical relay through oligoureas 23/06/2005 1, 21+6n Diastereoselectivity

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Effect of the chiral sulfoxide

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n = 1 : Distinguishable diastereomers n = 2 : not effect on the d 3 -isopropyl 73.5 ee% Still an equilibrium between the two helices

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What is the problem ? The sulfoxide controls the first axisThe first urea doesn't control the next one

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How to solve it ? Is the R group can drive the equilibrium to only one helix ??? Calculation using Spartan (density functional level) shows a minimum energy for the helicoidal structure First answer :

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How to introduce the R group ?

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When the urea are connected on ortho Broad signals Diastereotopic CH 3 Crystallisation in a chiral space group

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