56194-27-5Relevant articles and documents
Substrate specificity for the epoxidation of terpenoids and active site topology of house fly cytochrome P450 6A1
Andersen, John F.,Walding, Jennifer K.,Evans, Philip H.,Bowers, William S.,Feyereisen, Rene
, p. 156 - 164 (1997)
Heterologous expression in Escherichia coli, purification, and reconstitution of house fly P450 6A1 and NADPH-cytochrome P450 reductase were used to study the metabolism of terpenoids. In addition to the epoxidation of cyclodiene insecticides demonstrated previously [Andersen et al. (1994) Biochemistry 33, 2171-2177], this cytochrome P450 was shown to epoxidize a variety of terpenoids such as farnesyl, geranyl, and neryl methyl esters, juvenile hormones I and III, and farnesal but not farnesol or farnesoic acid. P450 6A1 reconstituted with NADPH-cytochrome P450 reductase and phosphatidylcholine did not metabolize α-pinene, limonene, or the insect growth regulators hydroprene and methoprene. The four geometric isomers of methyl farnesoate were metabolized predominantly to the 10,11-epoxides, but also to the 6,7-epoxides and to the diepoxides. The 10,11-epoxide of methyl (2E,6E)-farnesoate was produced in a 3:1 ratio of the (10S) and (10R) enantiomers. Monoepoxides of methyl farnesoate were metabolized efficiently to the diepoxides. Methyl farnesoate epoxidation was strongly inhibited by a bulky substituted imidazole. The active site topology of P450 6A1 was studied by the reaction of the enzyme with phenyldiazene to form a phenyl-iron complex. Ferricyanide-induced in situ migration of the phenyl group showed formation of the N-phenylprotoporphyrinporphyrin IX adducts in a 17:25:33:24 ratio of the N(B):N(A):N(C):N(D) isomers. These experiments suggest that metabolism of xenobiotics by this P450, constitutively overexpressed in insecticide-resistant strains of the house fly, is not severely limited by stereochemically constrained access to the active site.
Superacidic cyclization of higher terpenoid acids and their esters
Vlad, P. F.,Ungar, N. D.,Tuen, Nguen Van
, p. 2404 - 2411 (2007/10/03)
The superacidic cyclization of aliphatic and partially cyclized C15-C25 terpenoid acids and their esters proceeds structure-selectively and stereospecifically, affording α-isomers of completely cyclized epimeric β,γ-unsaturated acids or esters; the configuration of their carboxylic or ester groups is predetermined by the configuration of the double bond conjugated with the carboxyl or ester groups in the starting compounds. - Key words: terpenoids; acids; esters, superacidic cyclization, selectivity.
Selective γ- Alkylation of Copper Enolates Derived from α,β-Unsaturated Acids: Factors Affecting Scope and Regio- and Stereoselectivity
Savu, Patricia M.,Katzenellenbogen, John A.
, p. 239 - 250 (2007/10/02)
Copper dienolates derived from α,β-unsaturated acids undergo alkylation at the γ-carbon with high regioselectivity.A systematic investigation has been made of several factors that affect the γ-alkylation process of the dienolate derived tiglic acid (1): alterations in the nature of the counterion, in the stoichiometry of cuprous ion, and in the nature of the electrophile.Compared to allylic electrophiles, nonallylic electrophiles react with copper dienolates sluggishly and with little selectivity for the γ-carbon; vinylic epoxides, however, are particularly goodalkylating agents.They undergo allylic transposition and react at the γ-carbon of the dienolate with high selectivity (70-90 percent), generating an allylic unit that forms part of a 1,5-diene skeleton oxygenated at both ends.Tiglic (1) and crotonic (3) acids react with vinylic epoxides to form a 1,5-diene with entirely E stereochemistry at the 2,3 double bond, while senecioic acid (2) forms a 1,5-diene with mostly Z stereochemistry at the 2,3 double bond.Geometry at the 6,7 double bond depends both on the α,β-unsaturated acid used and on the structure of the epoxide.With allylic electrophiles under direct (SN2) attack, stereochemical analysis showed that some isomerization occurs around the 6,7 double bond (derived from the electrophile).Addition of cuprous ion to the lithium dianion of 2-hexenoic acid (17) was found to enhance the regioselectivity of γ alkylation, but a subsequent Michael addition reaction limits the potential of γ alkylation in this system.
