Linked Life Data

16196061

Source:http://linkedlifedata.com/resource/pubmed/id/16196061

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
2005-11-23
pubmed:abstractText
Enhancing atom economy of the metal-catalyzed asymmetric allylic alkylation (AAA) shifts from the usual nucleophilic displacement of a leaving group to an addition of a pronucleophile to a double bond. Using 1-alkoxyallenes as proelectrophiles, the palladium-catalyzed AAA proceeds with 1,3-dicarbonyl compounds as pronucleophiles with excellent regioselectivity and enantiomeric excess under optimized conditions. The pH of the medium proved crucial for reactivity/selectivity. By using the more acidic Meldrum's acids, the reactions required a co-catalytic amount of Brønsted acid, such as trifluoroacetic acid. Single regioisomeric products of 82-99 % ee were obtained. On the other hand, the less acidic 1,3-diketones failed to react under such conditions. The fact that a less acidic acid like benzoic acid sufficed, suggested the need for general base catalysis as well. Thus, a mixture of triethylamine and benzoic acid proved optimal (ee's 93-99). Employment of the (R,R)-phenyl Trost ligand gave a product with S configuration. A model to rationalize the results has been developed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0947-6539
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7075-82
pubmed:dateRevised
2009-8-4
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Enantioselective palladium-catalyzed addition of 1,3-dicarbonyl compounds to an allene derivative.
pubmed:affiliation
Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA. bmtrost@stanford.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural