A Simple Enantioselective Synthesis of the Biologically Active Tetracyclic Marine Sesterterpene Scalarenedial

A Short Synthesis of (±)-Matrine

“…The resulting mixture was then poured into a half-saturated aqueous solution of NH 4 Cl (40 mL), the organic phase was separated, and the aqueous phase was extracted with ether (2 Â 20 mL …”

“…Six-membered ring closure via radical intermediates is usually slower and therefore more difficult to accomplish than the formation of five-membered rings. [3] Earlier work on simpler bicyclic perhydroquinolizidines by Beckwith et al [4] revealed that premature reduction can occur in competition with the desired cyclization when the radical is generated with tributyltin hydride; slow (syringe pump) addition of the stannane was necessary. We hoped to avoid such a shortcoming by exploiting the inherently long lifetime of radicals created by the xanthate transfer process.…”

“…[3] Guilard et al reported recently on the synthesis and the spectroscopic characterization of some metalloporphyrin derivatives that are able to form micellar aggregates. [4] The use of an organized medium [5] is known to strongly affect the rate and the selectivity of many organic reactions [6] as well as some metal-catalyzed reactions. [7] With this aim we began a study on the synthesis and the reactivity of porphyrin derivatives bearing a suitable, appended functionality making them soluble in the micellar phase.…”

A Biomimetic Synthesis of Sacculatane Diterpenoids

“…This mixture was separated by column chromatography on silica gel. The spectral data of racemic 17a were identical with those of known optically active product [15].…”

“…The geranyllinalool (13) was acetylated under standard conditions to geranyllinalyl acetate (15), which was isomerized with [PdCl 2 (MeCN) 2 ] to the mixture (ca. 85 : 15) of (2E)-and (2Z)-geranylgeranyl acetates 16 (Scheme 3) [13].…”