title: From highly enantioselective catalytic reaction of 1,3-diynes with aldehydes to facile asymmetric synthesis of polycyclic compounds.
abstract: (S)-1,1'-Binaphth-2-ol (BINOL) in combination with ZnEt(2), Ti(O(i)Pr)(4), and biscyclohexylamine was found to catalyze the highly enantioselective (83-95% ee) addition of various 1,3-diynes to aldehydes of diverse structures. This method provides a convenient pathway to generate a number of optically active dienediynes as the acyclic precursors to polycyclic compounds. The chiral dienediynes undergo highly chemoselective Pauson-Khand (PK) cycloaddition in benzaldehyde by using [Rh(cod)Cl](2) as the catalyst in the presence of rac-BINAP. High diastereoselectivity (up to >20:1) has also been achieved with the chiral dienediyne substrates containing a bulky substituent adjacent to the chiral center. In the presence of the Grubbs II catalyst, ring-closing enyne metathesis of the PK cycloaddition products led to the formation of the desired 5,5,7- and 5,5,8-fused tricyclic compounds. Further highly diastereoselective Diels-Alder reaction of a 5,5,7-tricyclic compound with maleic anhydride produced a 5,5,7,6-polycyclic product. The asymmetric synthesis of polycyclic compounds from optically active dienediynes has established a novel and efficient synthetic route to the structural framework of many biologically significant molecules.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Turlington
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Du
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Ostrum
authors.forename: Vishaka
authors.initials: V
authors.lastname: Santosh
authors.forename: Kathryne
authors.initials: K
authors.lastname: Wren
authors.forename: Tony
authors.initials: T
authors.lastname: Lin
authors.forename: Michal
authors.initials: M
authors.lastname: Sabat
authors.forename: Lin
authors.initials: L
authors.lastname: Pu
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D053280:Diynes / Q000737:chemistry*; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D053280:Diynes; D011083:Polycyclic Compounds