Source:http://linkedlifedata.com/resource/pubmed/id/11681946
| Subject | Predicate | Object | Context |
|---|---|---|---|
| pubmed-article:11681946 | rdf:type | pubmed:Citation | lld:pubmed |
| pubmed-article:11681946 | lifeskim:mentions | umls-concept:C0443286 | lld:lifeskim |
| pubmed-article:11681946 | lifeskim:mentions | umls-concept:C0220781 | lld:lifeskim |
| pubmed-article:11681946 | lifeskim:mentions | umls-concept:C1883254 | lld:lifeskim |
| pubmed-article:11681946 | pubmed:issue | 22 | lld:pubmed |
| pubmed-article:11681946 | pubmed:dateCreated | 2001-10-29 | lld:pubmed |
| pubmed-article:11681946 | pubmed:abstractText | Treatment of alpha-aryl-beta-bromo(or chloro)-alpha-nitrosoethylene, prepared in situ from alpha-monobromo(or chloro)ketoximes and sodium carbonate in ether at rt, with allytrimethylsilane afforded exclusively trans-(4S,6S)- and trans-(4R,6R)-3-aryl-4-halo-6-[(trimethylsilyl)methyl]-5,6-dihydro-4H-1,2-oxazines 10 albeit in low yields. Similar treatment of beta-halo-alpha-nitrosoethylenes with ethyl vinyl ether, however, gave single stereoisomers, i.e., cis-(4S,6S)- and cis-(4R,6R)-6-ethoxy-4-halo-5,6-dihydro-4H-1,2-oxazines 11, in moderate to good yields. The result is in contrast to the reported predominant formation of trans-11a by a radical reaction. On the other hand, similar reactions with tert-butyl vinyl ether at 30 degrees C gave diastereomeric mixtures of cis-(4S,6S)-, cis-(4R,6R)-, trans-(4S,6R)-, and trans-(4R,6S)-6-(tert-butoxy)-4-halo-5,6-dihydro-4H-1,2-oxazines 12. In contrast to compounds 11, the major isomers have (4S,6R) and (4R,6S) configurations. The tendency of a [4 + 2] cycloaddition reaction is consistent with that observed in the Diels-Alder reaction with inverse-electron demand. The stereochemistries of compounds 10-12 were assigned on the basis of the (1)H NMR coupling constants, which were unambiguously determined by the decoupling experiments. All reactions leading to compounds 10-12 proceed with very high regioselectivity. Diastereoselectivity and high regioselectivity are understood in terms of the frontier orbital method. It has been found that cis-12g is isomerized to a mixture of stereoisomers in favor of the trans-isomer in the presence of HClO(4) (72%) in CHCl(3) at rt. | lld:pubmed |
| pubmed-article:11681946 | pubmed:language | eng | lld:pubmed |
| pubmed-article:11681946 | pubmed:journal | http://linkedlifedata.com/r... | lld:pubmed |
| pubmed-article:11681946 | pubmed:status | PubMed-not-MEDLINE | lld:pubmed |
| pubmed-article:11681946 | pubmed:month | Nov | lld:pubmed |
| pubmed-article:11681946 | pubmed:issn | 0022-3263 | lld:pubmed |
| pubmed-article:11681946 | pubmed:author | pubmed-author:KimKK | lld:pubmed |
| pubmed-article:11681946 | pubmed:author | pubmed-author:YoonS CSC | lld:pubmed |
| pubmed-article:11681946 | pubmed:author | pubmed-author:MesaOO | lld:pubmed |
| pubmed-article:11681946 | pubmed:issnType | lld:pubmed | |
| pubmed-article:11681946 | pubmed:day | 2 | lld:pubmed |
| pubmed-article:11681946 | pubmed:volume | 66 | lld:pubmed |
| pubmed-article:11681946 | pubmed:owner | NLM | lld:pubmed |
| pubmed-article:11681946 | pubmed:authorsComplete | Y | lld:pubmed |
| pubmed-article:11681946 | pubmed:pagination | 7334-41 | lld:pubmed |
| pubmed-article:11681946 | pubmed:dateRevised | 2003-10-31 | lld:pubmed |
| pubmed-article:11681946 | pubmed:year | 2001 | lld:pubmed |
| pubmed-article:11681946 | pubmed:articleTitle | Hetero-Diels-Alder reactions of alpha-aryl-beta-monohalo-alpha-nitrosoethylenes: diastereoselective synthesis of 6-substituted 3-aryl-4-halo-5,6-dihydro-4H-1,2-oxazines. | lld:pubmed |
| pubmed-article:11681946 | pubmed:affiliation | School of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea. | lld:pubmed |
| pubmed-article:11681946 | pubmed:publicationType | Journal Article | lld:pubmed |