ABSTRACT
The axial-equatorial conformational isomer distribution of the reactant diazoacetoacetate or its metal carbene intermediate is reflected in Rh(II) catalyzed oxonium ylide forming reactions of 3-(trans-2-arylvinyl)tetrahydropyranone-5-diazoacetoacetates that afford diastereoisomeric products for both the symmetry-allowed [2,3]- and the formally symmetry-forbidden [1,2]-oxonium ylide rearrangements.
Subject(s)
Acetoacetates/chemistry , Onium Compounds/chemistry , Rhodium/chemistry , Catalysis , Crystallography, X-Ray , Methane/analogs & derivatives , Molecular Conformation , Molecular Structure , StereoisomerismABSTRACT
Dirhodium catalyzed reactions of aryl-substituted tetrahydropyranone diazoacetoacetates produce ylide intermediates that unexpectedly yield two oxabicyclo[4.2.1]-nonane diastereoisomers, but a single diastereoisomer is formed by increasing the steric bulk of the aryl substituent.
Subject(s)
Acetoacetates/chemistry , Bridged Bicyclo Compounds/chemistry , Pyrones/chemistry , Rhodium/chemistry , Catalysis , Models, Molecular , StereoisomerismABSTRACT
Heating of the solid ammonium salts obtained from treatment of mellitic acid with 3 equiv of a primary amine yields trisubstituted mellitic triimides via dehydration and imide ring closure. This surprisingly simple synthetic approach is amenable to incorporation of alkyl, aryl, and amino acid ester substituents, thereby opening broad access to a family of C(3)-symmetric organic electron acceptors.
