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Optically Pure 1,2‐Bis[( o ‐alkylphenyl)phenylphosphino]ethanes and Their Use in Rhodium‐Catalyzed Asymmetric Hydrogenations of α‐(Acylamino)acrylic Derivatives
Author(s) -
Wada Yoshiyuki,
Imamoto Tsuneo,
Tsuruta Hideyuki,
Yamaguchi Kentaro,
Gridnev Ilya D.
Publication year - 2004
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404043
Subject(s) - rhodium , chemistry , diphosphines , asymmetric hydrogenation , asymmetric induction , enantioselective synthesis , catalysis , stereochemistry , phosphine , crystal structure , chirality (physics) , medicinal chemistry , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , quark , nambu–jona lasinio model
Optically pure ( S,S )‐1,2‐bis[( o ‐alkylphenyl)phenylphosphino]ethanes 1a–d were prepared in four steps from phenyldichlorophosphine via phosphine‐boranes as the intermediates. The rhodium complexes 5a–d of these diphosphines were used for the asymmetric hydrogenations of α‐(acylamino)acrylic derivatives including β‐disubstituted derivatives. Markedly high enantioselectivity (78–>99%) was observed for the reduction of β‐monosubstituted derivatives. β‐Disubstituted derivatives were also reduced in considerably high enantioselectivity (up to 90%). The single crystal X‐ray analysis of the rhodium complex 5c of ( S,S )‐1,2‐bis[phenyl(5′,6′,7′,8′‐tetrahydronaphthyl)phosphino]ethane ( 1c) revealed its δ‐type structure with face orientation of the two tetrahydronaphthyl groups and edge orientation of the two phenyl groups. This conformation corresponds to that of the rhodium complex of 1,2‐bis[( o ‐methoxyphenyl)phenylphosphino]ethane (DIPAMP); the rhodium complex of ( R,R )‐DIPAMP, whose chirality at phosphorus is opposite that of 5c , exhibits a λ‐type structure with the face orientation of the two o ‐methoxyphenyl groups and the edge orientation of the two phenyl groups. The conformational similarity of these rhodium complexes as well as the stereochemical outcome in the asymmetric hydrogenations means that the coordinative interaction of the methoxy group of DIPAMP with rhodium metal is not the main factor that affects asymmetric induction.