A synthesis of (+/-)-sparteine.
In a synthesis of racemic sparteine, Diels-Alder reaction between dimethyl bromomesaconate 14 and dicyclopentenyl 4, followed by cyclopropane formation, set up the stereochemistry at C-1 and C-5 as S and R, respectively, in a meso intermediate 8. The stereochemistry at C-2 and C-4 was then secured by a moderately diastereoselective protonation of the bis-enolate 17 derived from the diester 8 by reductive cleavage with lithium in liquid ammonia. The C=C in the racemic diester 19 was ozonolysed and the diketone converted by Beckmann rearrangement into the bis-lactam . Reduction of the bis-lactam with lithium aluminium hydride and intramolecular nucleophilic displacement gave racemic sparteine 1. Some ideas for making this synthesis amenable to a synthesis of enantiomerically enriched sparteine are presented.
Buttler
Thomas
T
Department of Chemistry, Cambridge, UK.
Fleming
Ian
I
Gonsior
Sabine
S
Kim
Bo-Hye
BH
Sung
A-Young
AY
Woo
Hee-Gweon
HG
D015394:Molecular Structure; D013034:Sparteine / Q000138:chemical synthesis* / Q000737:chemistry
D013034:Sparteine