نتایج جستجو برای: ring opening of epoxides

تعداد نتایج: 21178628  

Journal: :Catalysts 2022

Ring opening reactions of strained heterocycles (epoxides, aziridines, thiiranes) by silyl chalcogenides, such as thiosilanes and selenosilanes, can be efficiently performed in a variety ionic liquids, which behave reaction media some cases also catalysts. This protocol enables an alternative access to β-functionalized sulfides selenides under mild conditions.

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی برق و کامپیوتر 1391

this thesis is presented 10 ghz voltage controlled ring oscillator for high speed application. the voltage controlled ring oscillator was designed and fabricated in 0.13یm cmos technology. the oscillator is 7-stages ring oscillator with one inverter replaced by nand-gate for shutting down in the ring oscillator during idle mode. tri-state inverter was used to control of 126 bit vector in ri...

Journal: :Chemical communications 2015
Shyeni Paul Yunqing Zhu Charles Romain Rachel Brooks Prabhjot K Saini Charlotte K Williams

Controlled routes to prepare polyesters and polycarbonates are of interest due to the widespread application of these materials and the opportunities provided to prepare new copolymers. Furthermore, ring-opening copolymerization may enable new poly(ester-carbonate) materials to be prepared which are inaccessible using alternative polymerizations. This review highlights recent advances in the ri...

Journal: :Macromolecules 2021

The ring-opening copolymerization of epoxides with isothiocyanates (ITCs) is explored for the first time. In presence phosphazenium benzoxide, investigated in this work including propylene oxide, ethylene and cyclohexene oxide were successfully copolymerized both an aromatic ITC, phenyl isothiocyanate, two aliphatic ITCs, ethyl isothiocyanate hexyl isothiocyanate. Effects phosphazene bases used...

Journal: :Chemical & Pharmaceutical Bulletin 2021

α,β-Unsaturated oximes underwent electrophilic epoxidation with in-situ-generated dimethyldioxirane to give the corresponding epoxides in good yields. This reaction is an example of “carbonyl umpolung” by transformation α,β-unsaturated ketones their oximes. Nucleophilic ring-opening reactions afforded α-substituted products. Shi asymmetric proceeded moderate enantioselectivity.

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز 1379

‏‎for the first time nakayama introduced qf-ring. in 1967 carl. faith and elbert a. walker showed that r is qf-ring if and only if each injective right r-module is projective if and only if each injective left r-modules is projective. in 1987 s.k.jain and s.r.lopez-permouth proved that every ring homomorphic images of r has the property that each cyclic s-module is essentialy embeddable in dire...

Journal: :Organic letters 2010
Alan Rolfe Thiwanka B Samarakoon Paul R Hanson

A formal [4+3] epoxide cascade protocol utilizing ambiphilic sulfonamides and a variety of epoxides (masked ambiphiles) has been developed for the generation of benzothiaoxazepine-1,1'-dioxides and oxathiazepine-1,1'-dioxides. This protocol combines an epoxide ring-opening with either an S(N)Ar or oxa-Michael cyclization pathway.

2012
Oksana Sereda Nicole Clemens Tatjana Heckel René Wilhelm

The application of imidazolinium and amidinium salts as soft Lewis acid organocatalysts is described. These salts were suitable catalysts for the activation of unsaturated thioesters in a Diels-Alder reaction and in the ring opening of thiiranes and epoxides. The products were isolated in good yields. The mild catalysts did not cause desulfurization of the products containing a thiol or thiocar...

The present study, for the first time, presents a feasible protocol for the preparation of β-cyclodextrin/ imidazolium based dicationic ionic liquid, [βCD/Im](OTs)2, and its application as an efficient and eco-friendly microvessel and host ionic liquid system for the regioselective ring opening of the epoxides in water. No evidence for the formation of diol by-products or side reacti...

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