نتایج جستجو برای: cyclization of time
تعداد نتایج: 21267950 فیلتر نتایج به سال:
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.
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 ...
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.
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...
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...
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...
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.
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...
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...
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...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید