Tadatoshi Aratani

Catalytic asymmetric synthesis of cyclopropanecarboxylic acids: an application of chiral copper carbenoid reaction

Reaction of alkyl diazoacetate with an olefin catalyzed by a chiral copper complex gives an optically active alkyl cyclopropanecarboxylate. This chiral copper carbenoid reaction was successfully applied to the synthesis of industrially valuable cyclopropanecarboxylic acids: (÷)-trans-chrysanthem ic acid, (÷)-cis-permethrinic acid and (+)-2,2-dimethylcyclopropanecarboxylic acid. A series of effective catalysts, chiral Schiff base-copper complexes, was prepared starting with an optically active a-amino acid to achieve more than 90% e.e. of the products. The chirality of the products was correlated with that of the catalyst on the basis of metallacyclobutane intermediates. CHIRAL COPPER CARBENOID REACTION (ref. 1) AND ITS APPLICATION TO CHRYSANTHEMIC ACID SYNTHESIS In 1966, the first example of asymmetric catalysis (ref. 2) by means of a soluble transition metal complex was reported by Prof. Nozaki and his coworkers. They decomposed ethyl diazoacetate in styrene in the presence of chiral copper complex (1) as a catalyst to give the products, transand cis-2-phenyl-cyclopropanecarboxylate (3 and 4), both in an optically active form (Eq 1). This finding demonstrated that the carbene derived from ethyl diazoacetate is not free but is combined with the chiral copper complex to form a carbene-copper complex (ref. 3), which is responsible for the asymmetric induction. Furthermore, the reaction provided a new method for the preparation of optically active cyclopropane derivatives of practical value, although the enantiomeric excess (e.e.) attained at that time was less than 10%. Ph COOEt

Asymmetric synthesis of permethric acid. stereochemistry of chiral copper carbenoid reaction

Abstract The most effective optical isomer (1 R - cis ) of permethric acid ( 2 , R = H), a potent intermediate in the production of synthetic pyrethroid, was enantioselectively prepared.

A synthesis of 4,7-dihydro-1H-dipyrrolo[3,2-b:2′,3′-d]pyrrole and 4,7-dihydro-4H-thieno[3,2-b]pyrrolo[2,3-d]pyrrole systems

Abstract The titled two systems ( 3 and 6 ), both new members of linearly fused heteroaromatics, were prepared using pyrrolo-annulation reaction: condensation of an aromatic aldehyde with azidoacetate followed by thermolysis of the resulting azidoacrylate.