title: Catalytic asymmetric difunctionalization of stable tertiary enamides with salicylaldehydes: highly efficient, enantioselective, and diastereoselective synthesis of diverse 4-chromanol derivatives.
abstract: Catalyzed by a chiral BINOL-Ti(OiPr)4 complex, various stable tertiary enamides reacted with salicylaldehydes to afford diverse cis,trans-configured 4-chromanols that contain three continuous stereogenic centers in good yields with excellent diastereoselectivity and enantioselectivity. The reaction proceeded through the addition of enamide to aldehyde followed by the intramolecular interception of the resulting iminium by the hydroxy group. Oxidation of the resulting 4-chromanols yielded almost quantitatively chroman-4-one derivatives which underwent diastereospecific reduction with NaBH4 to produce cis,cis-configured 4-chromanols.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Ling
authors.initials: L
authors.lastname: He
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.forename: De-Xian
authors.initials: DX
authors.lastname: Wang
authors.forename: Mei-Xiang
authors.initials: MX
authors.lastname: Wang