Development of an additive-controlled, SmI2-mediated stereoselective sequence: Telescoped spirocyclisation, lactone reduction and Peterson elimination.
Studies on SmI2-mediated spirocyclisation and lactone reduction culminate in a telescoped sequence in which additives are used to "switch on" individual steps mediated by the electron transfer reagent. The sequence involves the use of two activated SmI2 reagent systems and a silicon stereocontrol element that exerts complete diastereocontrol over the cyclisation and is removed during the final stage of the sequence by Peterson elimination. The approach allows functionalised cyclopentanols containing two vicinal quaternary stereocentres to be conveniently prepared from simple starting materials.
University of Manchester, School of Chemistry, Oxford Road, Manchester M13 9PL, United Kingdom.
Brice
B
Sautier
Karl D
KD
Collins
David J
DJ
Procter
Peterson elimination; cyclisation; free radical; reduction; samarium; telescoped process