نتایج جستجو برای: emmons
تعداد نتایج: 328 فیلتر نتایج به سال:
[structure: see text] The asymmetric total synthesis of (-)-callystatin A has been achieved. The key steps generating the stereogenic centers rely on the asymmetric alpha-alkylation of aldehydes or ketones exploiting the SAMP/RAMP hydrazone alkylation methodology, as well as an enzymatic enantioselective reduction of a 3,5-dioxocarboxylate. For the construction of the alkene moieties, highly se...
The C-6 substituted tryptophan di- and tri-peptides and , representing the tryptophan core of stephanotic acid, have been synthesized, the key steps being the formation of the phosphono-di- and tri-peptides and by a highly chemoselective rhodium(II) catalyzed carbene N-H insertion reaction, their subsequent Horner-Wadsworth-Emmons reactions with N-Boc-6-bromoindole-3-carboxaldehyde, and the rho...
The N-acetylcystamine (SNAC) thioester of dodecapentaenoic acid, an analog of a putative intermediate in the biosynthesis of Heat Stable Antifungal Factor (HSAF), is synthesized. Key steps include sequential Horner-Emmons homologations with the Weinreb amide of diethylphosponoacetic acid, and thioesterification of an aldol-derived 3-hydroxyalkanoate, which serves as a stable precursor of the se...
An o-phenylenevinylene-bridged tetrapyrrolic macrocycle (2) was synthesized by means of a Horner-Wadsworth-Emmons reaction between benzylbisphosphonate and SEM-protected diformylpyrrole, followed by deprotection of the SEM groups. This conformationally flexible tetrapyrrole can be considered as an expanded calix[4]pyrrole analogue, which acts as a receptor for the chloride and bromide anions in...
A convenient synthesis of 3,4-didehydroretinal was developed. The Horner-Emmons reaction between 3,4-didehydro-beta-ionone and diphenyl phosphonate in the presence of crown ether gave the retinonitrile as an isomeric mixture, in which the newly produced double bond was predominantly 11Z-form. After separation of the 11Z-form retinonitrile, it was converted into the corresponding retinal in good...
This is a discussion of the paper “Housing, Monetary Policy, and the Recovery,” by Michael Feroli, Ethan Harris, Amir Sufi, and Kenneth West. The paper is part of the 2012 U.S. Monetary Policy Forum. * This version: 23 February 2012. I appreciate helpful comments from the St. Louis Fed research staff, especially Bill Emmons, Carlos Garriga, and Rajdeep Sengupta. Any views expressed are my own a...
A short and practical synthesis of oseltamivir was accomplished in 11 steps from inexpensive and abundant diethyl D-tartrate starting material. This azide-free route featured an asymmetric aza-Henry reaction and a domino nitro-Michael/Horner-Wadsworth-Emmons (HWE) reaction as the key steps to construct the relevant cyclohexene ring of the product, which provided an economical and practical alte...
mab-21 has been identified as a critical component required for sensory organ identity establishment in Caenorhabditis elegans. [Chow, K.L., Emmons, S.W., 1994. Development 120, 2579-2592; Chow, E. L., Hall, D.H., Emmons, S.W., 1995. Development 121, 3615-3625]. Human and mouse homologs of this gene have been isolated and their transcripts are predominantly detected in the eye and cerebellum [M...
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