[reaction: see text] Asymmetric total syntheses of acid-sensitive (-)-caparrapi oxide (1) and (+)-8-epicaparrapi oxide (2) from farnesol (9) were achieved using Sharpless-Katsuki epoxidation and Lewis acid-assisted chiral Bronsted acid (chiral LBA)-induced polyenecyclization as key steps. Furthermore, (-)-1 could be directly synthesized from (S)-nerolidol (3) and (R)-LBA with 88% ds by reagent control
Synthesis of Heterocyclic Terpenoids by Promiscuous Squalene-Hopene Cyclases
作者:Miriam Seitz、Per-Olof Syrén、Lisa Steiner、Janosch Klebensberger、Bettina M. Nestl、Bernhard Hauer
DOI:10.1002/cbic.201300018
日期:2013.3.4
Promiscuous enzymes: The substrate promiscuity of squalene–hopenecyclases has been explored and applied in the enzyme‐catalyzed synthesis of heterocyclic terpenoids. Features of this work include cyclizationreactions without pyrophosphate activation, and stereospecific ring closure of substrates of varying chain length and terminal nucleophile. This provides a biocatalytic alternative to traditional
(+)-Nerolidol was treated with 2,4,4,6-tetrabromocyclohexa-2,5-dienone to afford the brominativecyclisation products α- and β-snyderols and 3-bromocaparrapi oxide and its 8-epimer; (±)-geranyl-linalool gave the analogous tricyclic ethers.
A new enantiospecific route toward monocarbocyclic terpenoids: Synthesis of (−)- caparrapi oxide
作者:Alejandro F. Barrero、Enrique J. Alvarez-Manzaneda、Rachid Chahboun、M. Coral Páiz
DOI:10.1016/s0040-4039(98)02119-4
日期:1998.12
A new and efficient strategy is described for carrying out the enantiospecific synthesis of monocarbocyclic terpenoids from (−)-sclareol (1). The key steps are the Grob scission of 11-p-toluenesulphonyloxydriman-7α-ol (2) to give the tobacco seco-sesquiterpene 3 and the Baeyer-Villiger oxidation of 4-[(1′S, 2′S)-2′-formyl-2′,6′,6′-trimethylcyclohexyl]-2-butanone (4), derived from 3. The first enantiospecific
The acid catalysed cyclization of β-hydroxy selenide (), which was prepared from nerolidol () the epoxide (), was carried out to give bicyclic ether () directly which was further transformed into caparrapl oxide ().