Applications of planar-chiral phosphaferrocene-oxazolines in asymmetric catalysis and enantioselective desymmetrization by carbon nucleophiles in the presence of chiral ligands

In PART I, the design and the synthesis of planar-chiral phosphaferrocene-oxazolines, a new class of P,N-ligands, are described. The modular nature of their structure allows easy access to a number of analogues in enantiomerically pure forms, facilitating the easy tunability of the chiral environment. These ligands are then applied to several transition metal-catalyzed asymmetric reactions. In Pd-catalyzed asymmetric allylic alkylations, it is established that the planar chirality of the phosphaferrocene, not the central chirality of the oxazoline subunit, is the dominant stereocontrol element. On the other hand, in Cu-catalyzed asymmetric reactions (conjugate additions of diethylzinc to acyclic enones, intramolecular Kinugasa reactions for polycyclic β-lactam synthesis, and [3+2] dipolar cycloadditions of azomethine imines to terminal alkynes), it is demonstrated that the central chirality of the oxazoline subunit is the dominant stereocontrol element, and that the planar chirality of the phosphaferrocene plays a subordinate, although significant, role. In PART II, the enantioselective desymmetrization of cyclic anhydrides and imides by carbon nucleophiles is described. By employing a Grignard reagent/chiral ligand complex as the nucleophile, a range of anhydrides and imides are effectively desymmetrized with uniformly high enantiomeric excess. In these reactions, (-)- sparteine is shown to be the ligand of choice for anhydride substrates, whereas a bisoxazoline is found to be most effective for imide substrates.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Shintani, Ryo, 1976-

Advisor dc:contributor.advisor

• Gregory C. Fu.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/30019

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30019