An asymmetric approach to spirocylic systems: A formal synthesis of zizaene

Citation
Rc. Hughes et al., An asymmetric approach to spirocylic systems: A formal synthesis of zizaene, J ORG CHEM, 66(16), 2001, pp. 5545-5551
Citations number
13
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
JOURNAL OF ORGANIC CHEMISTRY
ISSN journal
00223263 → ACNP
Volume
66
Issue
16
Year of publication
2001
Pages
5545 - 5551
Database
ISI
SICI code
0022-3263(20010810)66:16<5545:AAATSS>2.0.ZU;2-Y
Abstract
A general route to enantiopure spirocarbocycles is described. The use of va rious chiral bicyclic lactams 1 that have been doubly alkylated with olefin ic halides gives good yields of alpha,alpha -disubstituted chiral lactams 2 which were cyclized to spiro-olefins using ring closure metathesis methodo logy (Grubbs' catalyst). These spirolactams 3, formed in generally excellen t yields, were shown to be smoothly transformed into spirocyclopentenone 6, spirocyclohexenone, 7, and spirolactams 8. Further demonstration of this s pirocyclization methodology was featured in a formal synthesis of zizaene, by preparing in enantiomeric form the Coates' intermediate 21. This synthet ic effort provided additional examples of the synthetic versatility of chir al bicyclic lactams 2a,b.