201. Palladium-Catalysed Intramolecular Cyclisations of Olefinic Propargylic Carbonates and application to the diastereoselective synthesis of enantiomerically pure (-)-α-thujone
     Oppolzer, W.; Pimm, A.; Stammen, B.; Hume, W. E.
     Helv. Chim. Acta 1997, 80, 623-639

Intramolecular [Pd₂(dba)₃]/tri(2-furyl)phosphine-catalysed (dba = dibenzylideneacetone, PhCHCHCOCHCHPh) cyclisations of olefinic propargylic carbonates I provided alk-1-enyl-(3-aza)bicyclo[3.1.0]-hexanes VIII in good yields. A palladium cascade sequence I → II → III → IV → VII → VIII is proposed. Furthermore, chiral propargylic carbonates such as 23, 24 and 25 allowed diastereoselective formation of bicyclo[3.1.0]hexanes 29, 30 and 31, respectively. The first diastereoselective synthesis of the monoterpene, (−)-α-thujone 40illustrates the potential of the method.

DOI : 10.1002/hlca.19970800302 

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