نتایج جستجو برای: mechanisms of cis and trans-Beta-lactam ring formation
تعداد نتایج: 24118100 فیلتر نتایج به سال:
the synthesis of cis-n-[a-carbobenzyloxy-b-(p-hydroxyphenyl)ethyl]-3-phthalimido-4-styryl-2-azetidinone is described. we have found that the electron-rich schiff bases can afford the cis-b-lactam ring even in the presence of the free hydroxyl functions. the mechanisms of cis and trans-b-lactam ring formation are discussed. the discussions are consistent with the recent publications.
The synthesis of cis-N-[a-carbobenzyloxy-b-(p-hydroxyphenyl)ethyl]-3-phthalimido-4-styryl-2-azetidinone is described. We have found that the electron-rich Schiff bases can afford the cis-b-lactam ring even in the presence of the free hydroxyl functions. The mechanisms of cis and trans-b-lactam ring formation are discuss...
we describe here a suitable approach for the synthesis of n-unsubstituted monocyclic b-lactams under mild reaction conditions by the annelation of imines with substituted acetylchlorides. in this method the reaily available phtalimidoacetyl chloride were allowed to react with - dibenzylideneiminotoluene (hydrobenzamide) in the presence of an equimolar amount of triethylamine in refluxing toluen...
the effect of alkyl substituents on the c-phenyl and/or the n-phenyl ring of benzophenylhydroxamic acid on their molecular structure and hydrogen bonding has been investigated. the predominant configuration in chcl3 is determined by steric and electronic effects. substituents on the c-phenyl ring favor the cis configuration, while substituents in the n-phenyl ring favor a trans configuration. t...
The effect of alkyl substituents on the C-phenyl and/or the N-Phenyl ring of benzophenylhydroxamic acid on their molecular structure and hydrogen bonding has been investigated. The predominant configuration in CHCl3 is determined by steric and electronic effects. Substituents on the C-phenyl ring favor the cis configuration, while substituents in the N-phenyl ring favor a trans c...
this research concentrates on the lithostratigraphy, biostratigraphy, microfacies and sedimentary environment of the asmari and gachsaran formations at southwest firuzabad. the thickness of the studied section in all 608.95 meters that 220.8 meters belong to the asmari formation and 387.95 meters belong to the gachsaran formation (champe and mol members). in the study area, the asmari formation...
in this paper the synthesis of some new polyaromatic monocyclic β-lactams has been reported. these cycloadducts have been synthesized by the [2+2] ketene-imine cycloaddition reaction known as the staudinger reaction. all of the products have been fully characterized by ir, 1h-nmr, 13c-nmr, mass spectroscopy and elemental analyses. the x-ray crystal structure of a cis β-lactam has been also pres...
abstract because of the many geopolitical, geo economical and geo strategically potentials and communicational capabilities of eco region, members can expand the convergence and the integration in base of this organization that have important impact on members development and expanding peace in international and regional level. based on quality analyzing of library findings and experts interv...
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...
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...
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