نتایج جستجو برای: emmons
تعداد نتایج: 328 فیلتر نتایج به سال:
Dimethylsulfonium methylide mediated olefination of 2-phenylethenylidene phosphonoacetate followed by the Horner-Wadsworth-Emmons reaction with aromatic aldehydes provided access to reactive 1,5-diaryl-2-ethoxycarbonyl [3]dendralenes which in situ underwent Diels-Alder cyclodimerisation leading to highly functionalised cyclohexenes with very high regio- and stereoselectivity.
(E,E)-1,4-bis(4'-aminostyryl)-2,5-bis(octyloxy)-benzene (6) and its derivative (E,E)-1,4-bis(4'-acetamidostyryl)-2,5-bis(octyloxy)-benzene (7) were synthesized and characterized after alkylation, bromomethylation, Horner-Emmons reaction and reduction from hydroquinone. In order to gain more molecular electronic data, HOMO and LUMO of compound 6 have been calculated by Gaussian 03 W.
Attractive carbocyclic structures are accessed via a highly regio- and enantioselective aminocatalytic γ-addition of cyclic enals to vinyl phosphonates followed by a one-pot intramolecular Horner-Wadsworth-Emmons reaction. It is also demonstrated that nitro olefins can act as electrophiles in a similar reaction concept, providing carbocycles in equally high stereoselectivity.
The enantioselective synthesis of passifloricin A has been achieved in high diastereomeric excess. The 1,3-polyol moiety was constructed by iterative proline-catalyzed sequential α-aminoxylation and Horner-Wadsworth-Emmons (HWE) olefination of aldehydes while the synthesis of lactone moiety was achieved by ring-closing metathesis (RCM).
A flexible stereoselective approach to the common C1-C14 skeleton present in natural products of the pseudomonic acid family is described. The strategy has been extended and the total synthesis of pseudomonic acid methyl monate C was achieved. The key synthetic reactions utilized include Achmatowicz rearrangement, Johnson-Claisen rearrangement, Julia-Kocienski olefination, and Horner-Wadsworth-...
A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an α,β unsaturated ester has been described. The use of a Horner-Wadsworth-Emmons reaction as a key step for generating the β'-amino-α,β-enones, permits access to a range of substrates under mild conditions and in moderate to high yield.
In 2003–07 summer balance was measured at altitudes between 1700 and 3382ma.s.l. on two glaciers onMount Rainier, Washington State, USA (46.85◦N, 121.72◦W; 4400ma.s.l.): south-facing Nisqually Glacier and east-northeast-facing Emmons Glacier. Upper-air temperatures at the nearest gridpoint in the NCEP/NCAR reanalysis database are used in a distributed (over altitude) positive-degreeday (PDD) mo...
The synthesis of a new 2,2'-bipyridyl functionalized oligovinylenephenylene (OVP-5) containing a methyl protected thiol using Heck coupling and the Horner-Wadsworth-Emmons reaction and is described. A key step involving a diisopropylcarbodiimide promoted dehydration of a stable β-hydroxyphosphonate intermediate was identified. The structure of precursor E-(4-(4-bromostyryl)phenyl)(methyl)sulfan...
We tabulate angularly reduced fourth-order many-body corrections to matrix elements for univalent atoms, derived in [A. Emmons, Phys. Rev. A 65 , 052115 (2002)]. In particular we focus on practically important diagrams complementary to those included cluster method truncated at single and double excitations. Derivation and angular reduction of a large number of diagrams have the help of symboli...
4H-Quinolizin-4-ones are a unique class of heterocycle with valuable physicochemical properties and which are emerging as key pharmacophores for a range of biological targets. A tandem Horner-Wadsworth-Emmons olefination/cyclisation method has been developed to allow facile access to substituted 4H-quinolizin-4-ones encoded with a range of functional groups.
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