Beilstein J. Org. Chem.2019,15, 2493–2499, doi:10.3762/bjoc.15.242
site providing a trans relationship between the hydroxy and the phosphine substituents.
Keywords: isopinocamphone; monoterpenes; phosphines; [2,3]-sigmatropic rearrangement; verbanone; Introduction
Chiral phosphorus compounds, despite many years of research, still enjoy unflagging interest of many
Adams catalyst was carried out in cyclohexane with 1 atm of hydrogen. The hydrogen pressure was increased to 10 atm for the reaction performed in an autoclave on a larger scale maintaining the high selectivity of hydrogen addition from the less hindered side of the molecule. (1R,2S,5R)-(+)-Verbanone (3
sulfuric acid under biphasic conditions. (−)-Isopinocamphone (8) was purified by fractional distillation and isolated in 78% yield. Then, 8 was subjected to an analogous reaction sequence that was used for (+)-verbanone (3), i.e., the synthesis of the enone in the first step followed by its 1,2-reduction
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Graphical Abstract
Scheme 1:
Synthesis of (1R,2R,4S,5R)-3-methyleneneoisoverbanol (6).