Linked Life Data

12662067

Source:http://linkedlifedata.com/resource/pubmed/id/12662067

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2003-3-28
pubmed:abstractText
Intramolecular Diels-Alder reactions of 2-azadiene models have been studied quantum chemically at the B3LYP/6-31G level in order to elucidate the stereochemical features of the cyclization step involved in the biosynthesis of paraherquamide A and VM99955. These cycloadditions take place through concerted transition states associated with [4 + 2] processes. Analysis of the energies along the competitive paths reveals that while the cycloadditions of the oxindoles present a large anti selectivity, the indoles show a low syn selectivity for the formation of the C20 stereogenic center that is larger for the reduced tertiary amide form. The presence of the C14 methyl of the beta-methylproline ring produces a low hindrance along the reaction coordinate for the syn approach of the isoprene framework, in agreement with the low facial selectivity found experimentally. An analysis of the electrophilicity and activation parameters for experimental models of the inter- and intramolecular Diels-Alder reactions reveals several significant factors controlling these biosynthetic cyclizations. The results are in reasonable agreement with the available experimental data.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3263
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2895-902
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Studies on the biosynthesis of paraherquamide A and VM99955. A theoretical study of intramolecular Diels-Alder cycloaddition.
pubmed:affiliation
Instituto de Ciencia Molecular, Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, E-46100 Burjassot, Valencia, Spain. domingo@utopia.uv.es
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't