The enzymatic basis for quinine 1 biosynthesis was investigated. Transcriptomic data from the producing plant led to the discovery of three enzymes involved in the early and late steps of the pathway. A medium-chain alcohol dehydrogenase (CpDCS) and an esterase (CpDCE) yielded the biosynthetic intermediate dihydrocorynantheal 2 from strictosidine aglycone 3. Additionally, the discovery of an O-methyltransferase specific for 6′-hydroxycinchoninone 4 suggested the final step order to be cinchoninone 16/17 hydroxylation, methylation, and keto-reduction.
Trenti, Francesco,Yamamoto, Kotaro,Hong, Benke,Paetz, Christian,Nakamura, Yoko,O'Connor, Sarah E.
supporting information
p. 1793 - 1797
(2021/04/05)
Diastereoselective Corey-Chaykovsky 9-epoxymethylation of cinchona alkaloids: Access to chiral scaffolds with diverse functionalities
Reaction of dimethylsulfonium methylide with Cinchona alkaloid ketones proceeds with complete diastereoselectivity to give epoxides of 8,9-like configuration. The reaction of dimethylsulfoxonium methylide gives different isomers, albeit with lower (4:1) selectivity. α-Epimerization of the alkaloid ketones resulted in formation of two separable diasteromeric products. The configurations of the epoxides were elucidated on the basis of NMR data combined with DFT calculations. Models explaining observed selectivity are discussed. The epoxides were efficiently transformed to a number of derivatives through selective SN2-type ring-opening reactions with various nucleophiles, often without the need of additional purification steps.
Boratynski, Przemyslaw J.,Skarzewski, Jacek
p. 4473 - 4482
(2013/06/27)
Synthetic approaches to 9-arylated Cinchona alkaloids: Stereoselective addition of Grignard reagents to cinchonanones and hydroxylation of 9-phenylcinchonanes
All 8,9-isomers of the 9-phenyl Cinchona alkaloids were obtained by autoxidation of 9-deoxy-9-phenyl-alkaloids and by the addition of Grignard reagents to the respective ketones. The diastereoselective addition of phenyl-, methyl-, and vinylmagnesium reag
Boratynski, Przemyslaw J.,Turowska-Tyrk, Ilona,Skarzewski, Jacek
scheme or table
p. 876 - 883
(2012/09/21)
A versatile cobalt(II)-Schiff base catalyzed oxidation of organic substrates with dioxygen: Scope and mechanism
Cobalt(II) complex 1a-f derived from Schiff bases act as efficient catalysts during the oxidation of wide range of organic substrates(e.g. alkenes, alcohols, benzylic compounds and aliphatic hydrocarbons) with dioxygen in the presence of aliphatic aldehydes or ketones or ketoesters. EPR studies on 1a-f complexes suggest that the aliphatic carbonyl compounds promote the formation of a cobalt(II)-superoxo species responsible for the oxidation of organic compounds. These studies also demonstrate the role of ligands on cobalt in controlling the chemoselectivity of these oxidations. A plausible mechanistic rational is also provided for these oxidations.
Punniyamurthy,Bhatia, Beena,Reddy, M. Madhava,Maikap, Golak C.,Iqbal, Javed
p. 7649 - 7670
(2007/10/03)
Cobalt catalyzed oxidation of secondary alcohols with dioxygen in the presence of 2-methylpropanal
Cobalt schiff base complex 2 catalyses the oxidation of a wide range of secondary alcohols to the corresponding ketones in the presence of dioxygen and 2-methylpropanal.