An efficient one-potmethod for the regioselective bromination of allylicalcoholderivatives (two-step reaction sequence) followed by Sonogashira, Negishi, or Suzuki–Miyaura coupling reactions in the same reaction vessel (three-step reaction sequence) has been developed. The key reaction in these one-pot systems is the regioselective DBU-promoted trans HBr elimination of vicinal dibromides bearing
The first totalsynthesis of (−)-5,6-seco-germacrane lactone has been achieved. The synthetic highlight of our approach includes sp2–sp3 Suzuki–Miyaura cross coupling of a vinyl bromide and an alkyl 9-BBN derivative. The vinyl bromide was easily prepared from the chiral lactonic building block using a one-pot regioselective bromination. The asymmetric carbon center of the alkyl boron compound was formed
Treatment of 1,2-dibromoalkanes with DBU effected an elimination reaction, leading to the alkynes. Oxygen substitution at the C3 position plays a critical role to abstract protons by inductive effects. By the application of this protocol, a totalsynthesis of sapinofuranone B 4 was accomplished.
Novel One-Pot Method for Chemoselective Bromination and Sequential Sonogashira Coupling
作者:Noriki Kutsumura、Kentaro Niwa、Takao Saito
DOI:10.1021/ol101110v
日期:2010.8.6
An efficient one-pot method for bromination-elimination of allyl alcohol derivatives and sequential Sonogashira coupling has been developed. A highlight of the method is chemoselective DBU-promoted elimination of vicinal dibromoalkanes having an adjacent O-functional group.