Publikationsdatum:
2011-03-25
Beschreibung:
Alkenes are found in many biologically active molecules, and there are a large number of chemical transformations in which alkenes act as the reactants or products (or both) of the reaction. Many alkenes exist as either the E or the higher-energy Z stereoisomer. Catalytic procedures for the stereoselective formation of alkenes are valuable, yet methods enabling the synthesis of 1,2-disubstituted Z alkenes are scarce. Here we report catalytic Z-selective cross-metathesis reactions of terminal enol ethers, which have not been reported previously, and of allylic amides, used until now only in E-selective processes. The corresponding disubstituted alkenes are formed in up to 〉98% Z selectivity and 97% yield. These transformations, promoted by catalysts that contain the highly abundant and inexpensive metal molybdenum, are amenable to gram-scale operations. Use of reduced pressure is introduced as a simple and effective strategy for achieving high stereoselectivity. The utility of this method is demonstrated by its use in syntheses of an anti-oxidant plasmalogen phospholipid, found in electrically active tissues and implicated in Alzheimer's disease, and the potent immunostimulant KRN7000.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3082443/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3082443/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meek, Simon J -- O'Brien, Robert V -- Llaveria, Josep -- Schrock, Richard R -- Hoveyda, Amir H -- GM-59426/GM/NIGMS NIH HHS/ -- R01 GM059426/GM/NIGMS NIH HHS/ -- R01 GM059426-12/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Mar 24;471(7339):461-6. doi: 10.1038/nature09957.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21430774" target="_blank"〉PubMed〈/a〉
Schlagwort(e):
Adjuvants, Immunologic/chemical synthesis/chemistry
;
Alkenes/*chemical synthesis/*chemistry
;
Amides/chemical synthesis/chemistry
;
Antioxidants/metabolism
;
Biological Products/*chemical synthesis/*chemistry
;
Catalysis
;
Ethers/chemistry
;
Galactosylceramides/chemical synthesis/chemistry
;
Molecular Structure
;
Molybdenum/chemistry
;
Plasmalogens/chemical synthesis/chemistry
;
Stereoisomerism
Print ISSN:
0028-0836
Digitale ISSN:
1476-4687
Thema:
Biologie
,
Chemie und Pharmazie
,
Medizin
,
Allgemeine Naturwissenschaft
,
Physik
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