Enantiodivergent synthesis of (+)- and (−)-isolaurepan
作者:Gonzalo Pazos、Manuel Pérez、Zoila Gándara、Generosa Gómez、Yagamare Fall
DOI:10.1016/j.tet.2012.08.094
日期:2012.11
The enantiodivergentsynthesis of (+)-and (−)-isolaurepan was achieved from a common chiral template easily available from tri-O-acetyl-d-glucal, using as key step a diastereoselective thermal Claisen rearrangement, combined with a ring expansion reaction using trimethylsilyldiazomethane.
A catalytic amount of TEMPO in the presence of PhI(OAc)2 effected oxidative lactonization of 1,6- and 1,7-diols, directly affording seven- and eight-membered lactones, respectively, in good yields.
Synthesis of medium ring ethers. Part 2. Synthesis of the fully saturated carbon skeleton of Laurencia non-terpenoid ether metabolites containing seven-, eight- and nine-membered rings
作者:Robert W. Carling、J. Stephen Clark、Andrew B. Holmes
DOI:10.1039/p19920000083
日期:——
A general method for the construction of medium ring ethers is described in which a 2-substituted cycloalkanone was subjected to a Baeyer–Villiger ring expansion to the lactone, Tebbe methylenation of which afforded the enol ether which was subjected to a hydroboration–oxidation sequence to afford the 2,n-disubstituted oxacycle (n= ring size). Application of this procedure has led to efficient syntheses
Synthetic methodology for the preparation of trans- and cis-2,9-disubstituted oxonanes
作者:Robert W. Carling、Neil R. Curtis、Andrew B. Holmes
DOI:10.1016/s0040-4039(01)93860-2
日期:1989.1
Methylenation of the racemic lactone (5), followed by stereoselective hydroboration, gave predominantly the trans-2,9-disubstituted oxonane (7) which was converted into the carbon skeleton (1) of obtusenyne (2). Epimerisation of the trans-aldehyde (18) gave the cis-compound (19). Relative stereochemistry was established by the asymmetric synthesis of trans-(2R),(9R)-dimethyloxonane (13) and meso cis-2,9-dimethyloxonane