From farnesol and (R)-methyloxirane the optically active bicyclic compounds 31 and 32 have been prepared. Cyclization of 31 led to the tricyclic compounds 29 and 30, respectively, which differ configurationally from forskolin only at C-8.
作者:Alexandre Larivée、John B. Unger、Mikaël Thomas、Conny Wirtz、Christophe Dubost、Shinya Handa、Alois Fürstner
DOI:10.1002/anie.201005850
日期:2011.1.3
Out of options? Even though a systematic approach was chosen, which led to a set of four diastereomeric macrolides modeled around the proposed structure of leiodolideB (see picture), the puzzle concerning the stereostructure of this cytotoxic metabolite derived from a deep‐sea sponge still remains unsolved.
Use of the Oxazole-Olefin Diels-Alder Reaction in the Total Synthesis of the Monoterpene Alkaloids (-)-Plectrodorine and (+)-Oxerine
作者:Masashi Ohba、Rie Izuta、Emi Shimizu
DOI:10.1248/cpb.54.63
日期:——
the total synthesis of two monoterpene alkaloids, (-)-plectrodorine [(-)-1] and (+)-oxerine [(+)-3], is presented. The key steps involved are the formation of the oxazole alcohol 10 from the gamma-butyrolactone 9 and the intramolecular Diels-Alder reaction of the oxazole-olefins 13a, b. Since the sign of specific rotation for the synthetic (+)-3 was different from that reported for natural oxerine,