Migration methoxycarbonyl groups

The Diels-Alder adduct 8 formed in a mixture with 7 by treatment of porphyrin 6 with dimethyl acetylenedicarboxylate undergoes a base-induced migration of a C —C double bond yielding a single diastereomer 9 with the thermodynamically favored tram arrangement of the methyl group and the methoxycarbonyl substituent.201... 

Migrations of arylazo groups were first detected in the l,2,3,4,5-penta(methoxycarbonyl) cyclopentadiene 259 (equation 89)119-122. The randomization mechanism was considered as most probable because the reaction rate increases with increase in the solvent polarity (AGf9S = 56.9 to 69.1 kJmol-1). 

More remote substituents may also participate in epoxide opening/rearrangement. Christol and coworkers examined several S,(6)-substituted-2,3-norbomene ejco-oxides under acidic conditions, and found that certain 5-endo substituents played a part in oxirane opening. For example, oxa rings were formed in reactions of substrates bearing 5-entfo-methoxycarbonyl or -hydroxymethyl groups. A novel 1,4-migration of chloride was also detected (equation 28). ... 

Migrations of arylazo groups were first detected in the l,2,3,4,5-penta(methoxycarbonyl)... 

Before detailing the chemistry occurring between Ru(dppe)(C0)2[C(0)0Me]2 and amines, we will briefly review the reactivity of this unusual bis(methoxycarbonyl) complex. The two isomers, 3 and 3 interconvert by an intramolecular "ligand-hopping" mechanism in which a methoxy group migrates from a methoxycarbonyl to an adjacent metal carbonyl ligand.(18) The primary coordination sphere of this octahedral, dfi, Ru2+ complex is inert towards substitution on the timescale of all the... 

Rapid, reversible migration of the acyl group in 2-acetoxy-3,7-dibenzyltropone and 2-methoxycarbonyl-3,7-dibenzyltropone has been observed tropylium ions (260 R = Me or OMe) are the supposed intermediates. Oxidation of cyclohepta-triene to tropylium ion by fluorosulphonic acid is accompanied by formation of sulphur dioxide, not hydrogen, and therefore must have been effected by reduction of the fluorosulphonic acid (or sulphur trioxide formed by equilibrium dissociation of the fluorosulphonic acid). ... 

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