Pure enantiomers from simple, symmetric dienophiles
摘要:
Starting from p-benzoquinone or 2-cyclopentene-1, 4-dione as dienophiles and the enantiomerically pure dienes 1a and 1b, high pressure cycloadditions led to chiral adducts. These were transformed in a regioselective manner to generate well defined stereogenic centres. A remarkably efficient electron density directed regioselectivity was discovered with 18c and 18d.
Dienes as chiral templates: easy access to pure (2S,3S,4R)-4-hydroxy-2,3-epoxycyclohex-5-en-1-one
作者:Antony Mauvais、Ekkehard Winterfeldt
DOI:10.1016/s0040-4020(01)87948-5
日期:1993.6
The title compound 6 was obtained stereospecifically through a concise sequence including a Diels-Alder reaction with the chiral diene 2 and the retro reaction. The Favorskiirearrangement starting from the intermediate epoxide 4 was found to be regioselective.
Examples of highly efficient kinetic resolutions with the bicyclic chiral cyclopentadiene 1 and several selected cyclic dienophiles are reported. In combination with a thermal retro-Diels-Alder process this procedure provides easy access to both enantiomers of these dienophiles.