115185-21-2Relevant academic research and scientific papers
FACILE MIGRATION OF ACYL GROUPS IN WAGNER-MEERWEIN TRANSPOSITIONS. ACID-CATALYZED REARRANGEMENTS OF 5,6-exo-EPOXY-7-OXA-2-BICYCLOHEPTANONE AND DERIVATIVES.
Drian, Claude Le,Vogel, Pierre
, p. 1523 - 1526 (1987)
The acid promoted rearrangements of 5,6-exo-epoxy-7-oxa-2-norbornyl derivatives allowed one to compare the "true" migratory aptitudes of acyl, alkyl and α-substituted alkyl groups in Wagner-Meerwein rearrangements.
Acid-Catalyzed Rearrangement of 5,6-exo-Epoxy-7-oxabicyclohept-2-yl Derivatives. Migratory Aptitudes of Acyl vs. Alkyl Groups in Wagner-Meerwein Transpositions
Drian, Claude Le,Vogel, Pierre
, p. 1703 - 1720 (2007/10/02)
In the presence of HSO3F/Ac2O in CH2Cl2, 2-exo- and 2-endo-cyano-5,6-exo-epoxy-7-bicyclohept-2-yl acetates (6a,b) gave products derived from the epoxide-ring opening and a 1,2-shift of the unsubstituted alkyl group (? bond C(3)-C(4)).In contrast, under similar conditions, the 5,6-exo-epoxy-7-oxabicycloheptan-2-one (6c) gave 5-oxo-2-oxabicycloheptane-3,7-diyl diacetates 20 and 21 arising from the 1,2-shift of the acyl group.Acid treatment of 5,6-exo-epoxy-2,2-dimethoxy-7-oxabicycloheptane (6d) and of 5,6-exo-epoxy-2,2-bis(benzyloxy)-7-oxabicycloheptane (6c) gave minor products arising from epoxide ring opening and the 1,2-shift of ? bond C(3)-C(4) and major products (25,29) arising from the 1,3-shift of a methoxy and benzyloxy group, respectively.Under similar conditions, 5,6-exo-epoxy-2,2-ethylenedioxy-7-oxabicycloheptane (6f) gave 1,1-(ethylenedioxy)-2-(2-furyl)ethyl acetate (32, major) and a minor product 33 arising from the 1,2-shift of ? bond C(3)-C(4).The following order of migratory aptitudes for 1,2-shifts toward electron-deficient centers has been established: acyl > alkyl > alkyl α-substituted with inductive electron-withdrawing groups.This order is valid for,competitive Wagner-Meerwein rearrangements involving equilibria between carbocation intermediates with similar exothermicites.
