Enantioselective synthesis of ansa-zirconocenes

Matthew D LoCoco; Richard F Jordan

doi:10.1021/ja045245g

Enantioselective synthesis of ansa-zirconocenes

J Am Chem Soc. 2004 Nov 3;126(43):13918-9. doi: 10.1021/ja045245g.

Authors

Matthew D LoCoco¹, Richard F Jordan

Affiliation

¹ Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA.

PMID: 15506741
DOI: 10.1021/ja045245g

Abstract

The reaction of the chiral chelated bis-amide complex Zr{(2R,4R)-PhNCHMeCH2CHMeNPh}Cl2(THF)2 (R,R-7) with lithium ansa-bis-indenyl reagents Li2[SBI](Et2O) (8a, SBI = (1-indenyl)2SiMe2) or Li2[EBI](Et2O) (8b, EBI = 1,2-(1-indenyl)2ethane) in THF affords the corresponding ansa-zirconocenes S,S-(SBI)Zr{(2R,4R)-PhNCHMeCH2CHMeNPh} (S,S,R,R-9a) or S,S-(EBI)Zr{(2R,4R)-PhNCHMeCH2CHMeNPh} (S,S,R,R-9b) in >95% isolated yield and >99% enantiomeric excess. Compound 9b was converted to the corresponding enantiomerically pure dichloride S,S-(EBI)ZrCl2 (S,S-10b) in 91% isolated yield by reaction with HCl in Et2O. The chiral diamine (2R,4R)-HPhNCHMeCH2CHMeNHPh (R,R-5) was recovered from this reaction.