the synthesis of (+)-(1R,3S)-cis-chrysanthemic acid is described. The use of readily available (-)-d-pantolactone as a starting point, application of ring-closing metathesis to form the cyclopentene intermediate, and Haller-Bauer/Grob-type fragmentation to form the target compound are the highlights of the present synthesis. ring closure - stereoselective synthesis- Wittig reaction- alkenes - metathesis
Synthesis of Enantiomerically Pure Eight- and Nine-Membered Lactones by Copper(I) Chloride/2,2’-Bipyridine-Catalyzed Cyclization
作者:Frank O.H. Pirrung、Henk Hiemstra、W. Nico Speckamp、Bernard Kaptein、Hans E. Schoemaker
DOI:10.1055/s-1995-4429
日期:1995.4
The stereocontrolled formation of eight- and nine-membered lactones by Cu(I)Cl/2,2’-bipyridine-catalyzed atom transfer cyclization of enantiomerically pure oxygen-substituted Ï-alkenyl di- and trichloroacetates is described. The lactones are formed exclusively via the endo-cyclization mode and generally show a characteristic cis-relationship between the C-5 and C-6 substituents due to a highly stereoselective ring closure and chlorine transfer.