The first asymmetric synthesis of (+)- and (−)-Dihydrokawain, an α-dihydropyrone isolated from the roots of Piper mythisticum, is reported. (+)-Dihydrokawain is the natural product and is of S-configuration.
methyl-3-hydroxy-5-phenylpentanoate and (6E)-ethyl 5-hydroxy-3-oxo-7-phenylhept-6-enoate is described in high enantiomeric excess and good yields. The effect of different lipases in different solvents has been screened using different acylating agents. This protocol has been extended for the preparation of enantiomerically pure biologically important kavalactones.
Efficient Enantioselective Hetero-Diels−Alder Reaction of Brassard's Diene with Aliphatic Aldehydes: A One-Step Synthesis of (<i>R</i>)-(+)-Kavain and (<i>S</i>)-(+)-Dihydrokavain
An efficient catalytic asymmetrichetero-Diels-Alderreaction of Brassard'sdiene with aliphatic aldehydes was reported. The catalyst, which was generated from (R)-BINOL, Ti(i-PrO)4, and 4-picolyl chloride hydrochloride, promoted the reaction smoothly to afford the corresponding alpha,beta-unsaturated delta-lactone derivatives in moderate-to-good yields (46-79%) with high enantioselectivities (up to
This invention relates to preparation of enantio-enriched compounds, and more particularly to enantio-enriched kavalactone compounds and derivatives thereof. The methods provide compounds that are useful as reagents, or building blocks, in the construction of other enantio-enriched compounds.
Heterogeneous enantioselective hydrogenation of 2-pyrones over cinchona-modified palladium
作者:Wolf-Rüdiger Huck、Tamas Mallat、Alfons Baiker
DOI:10.1039/b108944g
日期:2002.1.24
Asymmetric hydrogenation of 4-alkoxy and 4-methyl derivatives of 2-pyrones to the corresponding dihydro- or tetrahydropyrones over cinchona-modified Pd/TiO2 is fast under ambient conditions and affords good yields and high ee. cis-Tetrahydropyrones are obtained with 98–99% de. The ee can be further increased by kinetic resolution.
不对称 氢化在环境条件下,在金鸡纳改性的Pd / TiO 2上2-吡喃酮的4-烷氧基和4-甲基衍生物转化为相应的二氢-或四氢吡喃酮是快速的并且提供了良好的产率和高ee。顺式-四氢吡喃酮的de含量为98-99%。ee可以通过动力学拆分进一步提高。