نتایج جستجو برای: cyclization of time

تعداد نتایج: 21267950  

Journal: :Molecules 2023

A mild, visible-light-induced, regioselective cascade sulfonylation-cyclization of 1,5-dienes with sulfonyl chlorides through the intermolecular radical addition/cyclization alkenes C(sp2)-H was developed. This procedure proceeds well and affords a mild efficient route to range monosulfonylated pyrrolin-2-ones at room temperatures.

پایان نامه :0 1374

to discuss my point, i have collected quite a number of articles, anthologies, and books about "wuthering heights" applying various ideas and theories to this fantastic story. hence, i have come to believe that gadamer and jauss are rightful when they claim that "the individaul human mind is the center and origin of all meaning," 3 that reading literature is a reader-oriented activity, that it ...

Journal: :European Journal of Organic Chemistry 2021

Oxazolo[5,4-f]quinoxalines, thiazolo[5,4-f]quinoxalines and pyrazino[b,e]isatins were all obtained from 5-iodo-6-aminoquinoxalines. While the first two families synthesized by nitrogen functionalization subsequent copper-catalyzed cyclization, latter was Sonogashira coupling, alkyne hydration, oxidative cyclization. Most of polycycles evaluated in biological tests.

Journal: :Chemistry 2006
Jarugu Narasimha Moorthy Apurba L Koner Subhas Samanta Nidhi Singhal Werner M Nau Richard G Weiss

The stereochemistry at C2 and C3 carbons controls the partitioning of triplet 1,4-biradicals of ketones 2 among various pathways. Differences in the major reaction pathways, for example, cyclization (syn) and fragmentation (anti), adopted by the diastereomeric 1,4-radicals of ketones 2 have permitted unprecedented diastereomeric discrimination in their lifetimes to be observed by nanosecond las...

Journal: :Journal of the American Chemical Society 2002
Lior Eshdat Harald Berger Henning Hopf Mordecai Rabinovitz

Cross-conjugated enediynes cannot follow the Bergman cycloaromatization as it involves a methylenediyne moiety with only five pi e(-), insufficient for aromatization. Under reductive conditions the cyclization is made feasible by generating a product with a Hückel number of pi electrons. We illustrate this principle and demonstrate for the first time an anionic cyclization of a cross-conjugated...

2015
Karen S. Harris Thomas Durek Quentin Kaas Aaron G. Poth Edward K. Gilding Brendon F. Conlan Ivana Saska Norelle L. Daly Nicole L. van der Weerden David J. Craik Marilyn A. Anderson

Cyclotides are diverse plant backbone cyclized peptides that have attracted interest as pharmaceutical scaffolds, but fundamentals of their biosynthetic origin remain elusive. Backbone cyclization is a key enzyme-mediated step of cyclotide biosynthesis and confers a measure of stability on the resultant cyclotide. Furthermore, cyclization would be desirable for engineered peptides. Here we repo...

Journal: :Chemical communications 2015
Bang Liu Ren-Jie Song Xuan-Hui Ouyang Yang Li Ming Hu Jin-Heng Li

We here describe a new palladium-catalyzed oxidative 6-exo-trig cyclization of 1,6-enynes at room temperature using tBuONO as an oxidant for the synthesis of 3-bicyclo[4.1.0]heptan-5-ones. This cascade strategy involves the hydration, cyclization and cyclopropanation sequence, and represents a new transition-metal-catalyzed oxidative cyclization of 1,6-enynes in a 6-exo-trig fashion.

2004
Sunggak Kim

The rsuiical cyclizations of N-aziridinyl imines and alkyl azides provided reliable methods for the formation of fiveand six-membered carbon-centered and nitrogen-centered radicals from acyclic precursors. NAziridinyl imino and azido groups were utilized as radical precursors as well as radical acceptors in radical cyclization. Furthermore, intramolecular addition of aminyl radicals to carbonyl...

Journal: :journal of nanostructures 2015
j. safaei-ghomi s. zahedi m. javid m. a. ghasemzadeh

this work described one pot syntheses of polysubstituted 2,6- dicyanoaniline and 2-(3-oxo-1,3-diarylpropyl) malononitrile derivatives in the presence of mgo nanoparticles (nps) under grinding conditions and microwave irradiation, respectively. the simple experimental procedure includes shorter reaction times, higher yields, lower cost and environmental friendliness. other remarkable features ar...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده مهندسی عمران 1388

چکیده روش های متعددی برای برآورد رواناب حاصل از بارش در حوضه های آبریز وجود دارد. یکی از این روش ها استفاده از مدل های هیدرولوژیکی است. با استفاده از مدل های هیدرولوژیکی و شبیه سازی فرآیندهای هیدرولوژیکی می توان با صرف کمترین زمان و هزینه، رواناب و مولفه های دیگر چرخ? هیدرولوژیکی را برآورد کرد. از آنجا که در حوضه های آبریز اندازه گیری تمام کمیت های مورد نیاز برای تحلیل رواناب ممکن نیست، انتخاب...

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