Steric effects on the control of endo/exo-selectivity in the asymmetric cycloaddition reaction of 3,4-dimethyl-1-phenylarsole.
The asymmetric cycloaddition reactions of 3,4-dimethyl-1-phenylarsole and (Z/E)-diphenyl-1-propenylphosphine/diphenyl-1-styrylphosphine promoted by a chiral organopalladium(ii) complex derived from (S)-[1-(dimethylamino)ethyl]naphthalene proceeded stereoselectively to generate different exo/endo-products. The reactions involving the (Z/E)-methyl substituted phosphines gave the individual optically pure exo- and endo-cycloadducts in very high stereoselectivity (33 : 1). However, when the methyl group was replaced by a Ph moiety both (Z/E)-phenyl substituted phosphines produced the same endo-cycloadduct in a stereoselectivity of 15 : 1. Every reaction produced five new chiral centers (four of them are sterically independent) in a single step and all three optically pure As-P heterobidentate ligands were obtained in high yields. The mechanism involved in the conversion of exo- to endo-product was investigated via density functional theory calculations. Computational results were consistent with the experimentally observed endo/exo-selectivity.
Ma
Mengtao
M
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
Lu
Ruifeng
R
Pullarkat
Sumod A
SA
Deng
Weiqiao
W
Leung
Pak-Hing
PH
D001151:Arsenic / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D009942:Organometallic Compounds; D010720:Phosphines; D010165:Palladium; D001151:Arsenic