title: Chiral overcrowded alkenes; asymmetric synthesis of (3S,3'S)-(M, M)-(E)-(+)-1,1',2,2',3,3',4,4'-octahydro-3,3',7,7'-tetramethyl-4, 4'-biphenanthrylidenes.
abstract: An asymmetric synthesis route towards (3S,3'S)-(M,M)-(E)-(+)-1,1',2, 2',3,3',4,4'-octahydro-3,3',7,7'-tetramethyl-4,4'-biphenanthrylidene was developed using the Evans procedure as a key step. The absolute configurations of the title compound and of its parent ketone were determined by CD spectroscopy and could be correlated with the stereochemical results of the asymmetric alkylation. Furthermore, a comparison was made with the known (3R,3'R)-(P,P)-(E)-(-)-1,1',2,2', 3,3',4,4'-octahydro-3,3',7,7'-dimethyl-4,4'-biphenanthrylidene. Finally, the X-ray crystallographic analysis of (3S,3'S)-(M, M)-(E)-(+)-1,1',2,2',3,3',4,4'-octahydro-3,3',7,7'-tetramethyl-4, 4'-biphenanthrylidene is presented.
authors.affiliation: Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Groningen, The Netherlands.
authors.forename: M K
authors.initials: MK
authors.lastname: Ter Wiel
authors.forename: N
authors.initials: N
authors.lastname: Koumura
authors.forename: R A
authors.initials: RA
authors.lastname: Van Delden
authors.forename: A
authors.initials: A
authors.lastname: Meetsma
authors.forename: N
authors.initials: N
authors.lastname: Harada
authors.forename: B L
authors.initials: BL
authors.lastname: Feringa
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D008958:Models, Molecular; D008968:Molecular Conformation; D010616:Phenanthrenes / Q000138:chemical synthesis* / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D007202:Indicators and Reagents; D010616:Phenanthrenes