نتایج جستجو برای: emmons
تعداد نتایج: 328 فیلتر نتایج به سال:
The synthesis and characterization of a set of conjugated polymers, poly(1,4-phenylene-ethynylene)-alt-poly(1,4-phenylene-vinylene)s (PPE-PPVs), with a dissymmetrical configuration (partial or total) of alkoxy side chains is reported. Five new polymers bearing octyloxy and/or octadecyloxy side chains at the phenylene-ethynylene and phenylene-vinylene segments, respectively, were obtained. Two s...
Coherence and congruence-based measures of personality integration were related to a variety of healthy personality characteristics. Functional coherence was defined as occurring when participants' "personal strivings" (R.A. Emmons, 1986) help bring about each other or help bring about higher level goals. Organismic congruence was defined as occurring when participants strive for self-determine...
We have developed two syntheses of vicenistatin and its analogues. Our first-generation strategy included the rapid and sequential assembly of the macrocyclic lactam by using an intermolecular Horner-Wadsworth-Emmons reaction between the C3-C13 fragment and the C1-C2, C14-C19 fragment, followed by an intramolecular Stille coupling reaction. The second-generation strategy utilized a ring-closing...
Hexahydropyrrolo[2,3-b]indoles 6 were synthesized in five steps from indolin-3-one 8 by a general and efficient method, in which elements of molecular diversity were readily added onto the 3a-position of the pyrrolo[2,3-b]indole ring system. Horner-Wadsworth-Emmons reaction of 2-allyloxyindolin-3-ones 7, derived from indolin-3-one 8 and a variety of allylic alcohols, smoothly proceeded with suc...
Maitotoxin (1) continues to fascinate scientists not only because of its size and potent neurotoxicity but also due to its molecular architecture. To provide further support for its structure and facilitate fragment-based biological studies, we developed an efficient chemical synthesis of the ABCDEFG segment 3 of maitotoxin. (13)C NMR chemical shift comparisons of synthetic 3 with the correspon...
The synthesis of QRSTUVWXYZA' domains 7, 8, and 9 of the highly potent marine neurotoxin maitotoxin (1), the largest secondary metabolite isolated to date, is described. The devised synthetic strategy entailed a cascade Takai-Utimoto ester olefination/ring closing metathesis to construct ring Y, a hydroxydithioketal cyclization/methylation sequence to cast ring X, a Horner-Wadsworth-Emmons coup...
It has been suggested that dipyrimadole might be effective in reducing the incidence of thrombosis by interfering with both platelet clumping and the early stages of blood clotting. Emmons et al (1965 a & b) found that dipyrimadole inhibited thrombus formation in injured rabbit vessels in vivo, and reduced platelet stickiness in vitro, and they suggested that dipyrimadole might be a useful agen...
The readily accessible -chlorophosphonates (OCH2CMe2CH2O)P(O)CH(Cl) C6H4-4-R [1: R=Me (a), OMe (b), Cl (c), H (d)] react with ferrocenecarboxaldehyde in the presence of NaH [Horner–Wadsworth–Emmons reaction] to give good yields of ferrocenyl substituted chlorostilbenes. The novel bis ferrocenyl butadiene C5H5FeC5H4 CH CH C(CN)CHC5H4FeC5H5 (9) as well as the ferrocenyl 2-cyano-1,3-butadienes 4-R...
This so-called Wittig reaction has a number of advantages over other olefination methods; in particular, it occurs with total positional selectivity (that is, an alkene always directly replaces a carbonyl group). By comparison, a number of other carbonyl olefination reactions often occur with double-bond rearrangement. In addition, the factors that influence Eand Z-stereoselectivity are well un...
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