Asymmetric hydrogenation of unfunctionalized trisubstituted and tetrasubstituted olefins

A highly reactive chiral catalyst for the asymmetric hydrogenation of aryl trisubstituted olefins was generated by combining the complex (EBTHI)MMe2 (EBTHI = ethylenebistetrahydroindenyl, M = Ti, Zr) with [PhMe2NH]+[(BC6F5)4]- under a hydrogen atmosphere. A number of unfunctionalized trisubstituted olefins could be hydrogenated rapidly at room temperature under 80 psig H2 with a wide range of ee's (7 97% ). Reduction of some substrates under a deuterium atmosphere revealed that olefins which gave low ee's were being isomerized to 1, 1-disubstituted olefins prior to reduction. In some cases, additional deuterium was introduced at nonolefinic carbon atoms, indicating that the metal complexes also catalyze directed C-H activation. The zirconium-based catalyst was also applied to the first highly enantioselective hydrogenations of unfunctionalized tetrasubstituled olefins. Hydrogenations of l ,2- dimethyi-3,4-dihydronaphthalene proceeded with high enantioselectivity, but were accompanied by side reactions. At 80 - 2000 psig H2, hydrogenations of a number of fully substituted unfunctionalized indenes proceeded cleanly to give mostly cis products with ee's of 78 - 99%; rates and enantioselectivities increased with increasing pressure. Again, deuteration experiments showed that isomerization processes may occur under the reaction conditions.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Chemistry

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1998

Author dc:creator

• Troutman, Malisa V. (Malisa Vaughn), 1970-

Advisor dc:contributor.advisor

• Stephen L. Buchwald.

• 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/1721.1/9636

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/9636