Analogues ofα-Campholenal (= (1R)-2,2,3-Trimethylcyclopent-3-ene-1-acetaldehyde) as Building Blocks for (+)-β-Necrodol (= (1S,3S)-2,2,3-Trimethyl-4-methylenecyclopentanemethanol) and Sandalwood-like Alcohols
relationships (SARs) of sandalwood-like alcohols derived from analogues of α-campholenal (= (1R)-2,2,3-trimethylcyclopent-3-ene-1-acetaldehyde), we isomerized the epoxy-isopropyl-apopinene (−)-2d to the corresponding unreported α-campholenal analogue (+)-4d (Scheme 1). Derived from the known 3-demethyl-α-campholenal (+)-4a, we prepared the saturated analogue (+)-5a by hydrogenation, while the heterocyclic aldehyde
Enantiopure cycloadducts have been prepared in good yield via oxime-nitrone-isoxazolidine cascade reactions involving the nucleophilic opening of enantiopure epoxides with oximes followed by 1,3-dipolar cycloaddition reactions with suitable dipolarophiles.