New chiral molybdenum metathesis catalysts : application to the enantioselective preparation of cyclic amines

Optically pure (R)-5,5',6,6',7,7',8,8'-octahydro-1,1'-bi-2-napthol was derivatized with mesityl groups in the 3 and 3' positions to give (R)-MES₂BitetH₂ 1.43. Addition of the di-potassium salt of 1.43 to (Ar[sub]prN)Mo(CHCMe₂Ph)(OTf)₂(DME) yielded [(Ar[sub]prN)Mo((R)-MES₂Bitet)(CHCMe₂Ph)(THF), (R)-1.44a. This material was studied in detail by variable temperature ¹H NMR spectroscopy with and without solvent additives (THF, DMF and MeCN). An X-ray study of (R)-1.44a showed it to crystallize as the THF adduct of an anti-alkylidene, in a distorted trigonal bipyramid. Complex (R)-1.44a was shown to be an active and selective catalyst for olefin metathesis for representative ARCM transformations to form dihydrofurans. CHAPTER 2: The first catalytic asymmetric ring-closing metathesis (ARCM) method for the synthesis of nitrogen-containing heterocycles was developed; this was accomplished via Mo-catalyzed desymmetrization of unsaturated prochiral amines to afford tetrahydropyridines (2.68a-e). The selectivity of this transformation was sensitive to the olefin substitution pattern of the prochiral amine. However, this novel method was also applicable for the formation seven-(2.84), and eight-membered (2.84) rings in high yield, with exceptional enantioselectivity. Importantly, this method remained highly effective when performed without solvent. Several chiral benzoazepines (2.95a-c) were also prepared via Mo- catalyzed ARCM. In these latter cases, the steric size of groups attached to the prochiral carbon was observed to affect both the rate and selectivity of ARCM. Related benzoazocine precursors (2.97 and 2.100) could not be successfully desymmetrized to cyclic amines.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Dolman, Sarah Jennifer, 1977-

Advisor dc:contributor.advisor

• Richard R. Schrock.

• 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/1721.1/17825

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17825