The cycloaddition of spirobutenolide 3 to the homochiral cyclopentadiene 1 at 6.5 kbar leads exclusively to cycloadduct 5. Subsequent Diels-Alder or Michael additions again favour the cyclohexenone double bond; this perfect chemo- regio- and face selectivity was employed for a short and efficient approach to the wistarin framework.
Enantiopure building blocks for marine natural products via differentiation of enantiotopic groups
作者:Winfried Beil、Peter G. Jones、Frank Nerenz、Ekkehard Winterfeldt
DOI:10.1016/s0040-4020(98)00158-6
日期:1998.6
The group and face-selective cycloaddition of the enantiopure cyclopentadiene 4 to the tyrosine-related spirocylohexadienone 10 provided a high yield of the enantiomericallypure cyclohexadienone 11. Stereoselective transformations at the remaining double bond followed by a thermal retro-process, finally giving rise to the chromophore of the marine agelorin antibioticcs isolated from the sponge Agelas
A Predictable Enantioselective Total Synthesis of (+)-Clavularin A
作者:Hilmar Weinmann、Ekkehard Winterfeldt
DOI:10.1055/s-1995-4061
日期:1995.9
Cycloadduct 9 was transformed into vinylsilane 11d in a conjugate addition-alkylation sequence. Epoxidation and subsequent hydrolysis provided the clavularin adduct 14, which on flash vacuum pyrolysis (FVP) gave (+)-clavularin A (1) in 91% yield.
环加合物 9 通过共轭加成-烷基化顺序转化为乙烯基硅烷 11d。环氧化反应和随后的水解反应产生了黄烷苷加合物 14,该加合物经闪蒸真空热解(FVP)得到了 (+)-clavularin A (1),收率为 91%。
A Simple Route to Enantiopure Fluorocyclohexenones
作者:Hilmar Weinmann、Ekkehard Winterfeldt
DOI:10.1055/s-1996-4217
日期:1996.3
The 4-fluoro substituted cyclohexadienone 10 was shown to undergo a very efficient differentiation of enantiotopic double bonds in a Diels-Alder cycloaddition process. Epoxidation followed by thermal retro reaction generated the enantiopure fluorocyclohexenone 13.
A wide range of cyclohexadienones has been synthesised in order to study their reactivity and their regio- and stereoselectivity with the enantiopure diene 1 under high-pressure conditions. Computational investigations were used to point out some parameters which affect the reactivity in this high chiral discrimination process. In addition, the resulting [4+2] cycloadducts allowed the preparation of new polyfunctional cyclohexenone derivatives.