A new access to cyclopenta[c]pyridine ring system: syntheses of (−)-plectrodorine and (+)-oxerine
作者:Masashi Ohba、Rie Izuta、Emi Shimizu
DOI:10.1016/s0040-4039(00)01824-4
日期:2000.12
Total syntheses of (−)-plectrodorine [(−)-1] and (+)-oxerine [(+)-3] possessing the cyclopenta[c]pyridine ring system have been accomplished through a route starting from the chiral γ-butyrolactone 7 and exploiting the intramolecular oxazole–olefin Diels–Alder reaction. The sign of specific rotation for the synthetic (+)-3 was in disagreement with that reported for natural oxerine, leaving the absolute
从手性γ-丁内酯开始的路线已经完成了具有环戊[ c ]吡啶环系统的(-)-plectrodorine [(-)- 1 ]和(+)-oxerine [(+)- 3 ]的总合成。7并利用分子内恶唑-烯烃Diels-Alder反应。合成(+)- 3的比旋转迹象与天然草皮的报道不同,使这种单萜生物碱的绝对构型不完整。
Convenient Formal Synthesis
of (+)-Grandisol through Lewis Acid Promoted Enantioselective
Pinacolic Rearrangement
cyclopropanation of an easily prepared chiral a-siloxylactone leads efficiently to an enantiomerically pure cyclopropanol derivative. The trimethylsilyl trifluoromethane sulfonate induced pinacol rearrangement allows high level of chirality transfer into a cyclobutanone, which is a useful intermediate in the total synthesis of (+)-grandisol.
Use of the Oxazole-Olefin Diels-Alder Reaction in the Total Synthesis of the Monoterpene Alkaloids (-)-Plectrodorine and (+)-Oxerine
作者:Masashi Ohba、Rie Izuta、Emi Shimizu
DOI:10.1248/cpb.54.63
日期:——
the total synthesis of two monoterpene alkaloids, (-)-plectrodorine [(-)-1] and (+)-oxerine [(+)-3], is presented. The key steps involved are the formation of the oxazole alcohol 10 from the gamma-butyrolactone 9 and the intramolecular Diels-Alder reaction of the oxazole-olefins 13a, b. Since the sign of specific rotation for the synthetic (+)-3 was different from that reported for natural oxerine,