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.
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.
Ter Wiel
M K
MK
Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Groningen, The Netherlands.
Koumura
N
N
Van Delden
R A
RA
Meetsma
A
A
Harada
N
N
Feringa
B L
BL
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
D000475:Alkenes; D007202:Indicators and Reagents; D010616:Phenanthrenes