The enantioselective deprotonation of the 8-oxabicyclo[3.2.1]octan-3-one with chiral lithium amides 5 and 6, in the presence of LiCl, gave the chiral lithium enolates which were in turn reacted with methyl cyanoformate. The resulting chiral b-keto esters were reduced with sodium amalgam to afford the 8-oxa-ecgonine- and 8-oxa-pseudoecgonine-like derivatives which allowed facile preparation of the (+)- and (-)-8-oxa-norcocaines and (+)- and (-)-8-oxa-pseudonorcocaines. The new synthesized 8-oxa analogues of cocaine showed good enantiomeric excesses in the range of 84-90%.
Enantioselective deprotonation of the 8-oxabicyclo[3.2.1]octan-3-one: Synthesis of 8-oxa-norcocaines and 8-oxa-pseudonorcocaines
SIMONI, Daniele;RONDANIN, Riccardo;
1999
Abstract
The enantioselective deprotonation of the 8-oxabicyclo[3.2.1]octan-3-one with chiral lithium amides 5 and 6, in the presence of LiCl, gave the chiral lithium enolates which were in turn reacted with methyl cyanoformate. The resulting chiral b-keto esters were reduced with sodium amalgam to afford the 8-oxa-ecgonine- and 8-oxa-pseudoecgonine-like derivatives which allowed facile preparation of the (+)- and (-)-8-oxa-norcocaines and (+)- and (-)-8-oxa-pseudonorcocaines. The new synthesized 8-oxa analogues of cocaine showed good enantiomeric excesses in the range of 84-90%.File in questo prodotto:
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