Ch7 - Bimolecular Reactions - supported by strong...

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H C Nuc CH 2 R' R H C LG R'H 2 C R CH 2 R' C LG H R C C H R H C Nuc CH 2 R' R H C Nuc R'H 2 C R H C C H R H R' LG C C R H R' H Ch. 7 ----- SN1, SN2, E1, E2 Nolta 2009 Nuc + LG SN2 or Bimolecular Substitution Electrophilic sp3 carbon (due to LG taking electrons) One-sided attack leads to inversion at C -stereocenters "invert" so watch for stereoselection One step slow step C C Nuc: R H R' H + Racemization at α center C+ intermediate -racemization at carbon if chiral at start. Base E2 or "Anti" elimination - FIND ALL POSSIBLE β Cs with Hs: The LG and the β H removed from the adjacent C must be in the same plane in order for the p orbitals to align, hence the "anti" conformation leads to the fastest E2. This alignment determines the conFguration of the double bond that forms ; if more than one β H is available on a β C, both double bond stereochemistries are possible (anti alignment of other big groups typically leads to stereopreference of one) if more than one β C has an available H the more
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This note was uploaded on 01/28/2011 for the course CHEM 215 taught by Professor Koreeda during the Spring '07 term at University of Michigan.

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