Base Promoted 1,4-Elimination Reactions : On the Origin of an Eventual syn-Stereoselectivity

Rate ratios were obtained for the base-catalyzed 1,4-dehydrochlorination of (E)- and (Z)-Me3CCCl:C:C:CClCMe3 to give Me3CC.tplbond.CC.tplbond.CCMe3. In the KOMe/MeOH or KOCMe3/Me2SO systems the reactivity of both isomers was similar. With KOCMe3 in Me3COH, THF or C6H6 the 2 isomers exhibited similar reactivity when 18-crown-6 was present, but the E isomer was much more reactive in its absence. These findings suggested a conveyor-belt-type transition state with an aggregate of the base interacting with the H and Cl atoms undergoing elimination. [on SciFinder (R)]

Published in:
Angewandte Chemie, International Edition, 20, 1041-1042
CAN 96:51540 22-4 Physical Organic Chemistry Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz. Journal 0044-8249 written in German. 79898-97-8 Role: RCT (Reactant), RACT (Reactant or reagent) (chlorination of); 79898-98-9 Role: RCT (Reactant), RACT (Reactant or reagent) (dehydrochlorination of); 79898-95-6; 79898-96-7 Role: RCT (Reactant), RACT (Reactant or reagent) (dehydrochlorination of, mechanism of); 6130-98-9P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of)

 Record created 2006-03-03, last modified 2018-12-03

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