نتایج جستجو برای: aza wittig reaction
تعداد نتایج: 417079 فیلتر نتایج به سال:
We report the phospha-bora-Wittig reaction for direct preparation of phosphaalkenes from aldehydes, ketones, esters, or amides. The transient phosphaborene Mes*P?B–NR2 reacts with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues oxaphosphetane intermediates in classical Wittig reaction. 1,2,3-Phosphaboraoxetanes undergo thermal Lewis acid-promoted cycloreversion, yielding phospha...
The mechanism of the Wittig reaction has long been a contentious issue in organic chemistry. Even now, more than 50 years after its announcement, its presentation in many modern undergraduate textbooks is either overly simplified or entirely inaccurate. In this review, we gather together the huge body of evidence that has been amassed to show that the Li salt-free Wittig reactions of non-stabil...
A metal-free protocol for the synthesis of substituted 1,6-dihydropyridines with quaternary stereogenic centers via a cascade aza-Wittig/6?-electrocyclization process has been developed. The high functional group compatibility and broad scope this method were demonstrated by using wide range easily available vinyliminophosphoranes ketones, yields up to 97%. modification obtained products allowe...
protonation of the reactive intermediates generated in the raction between dalkyl acetylenedicarboxylates and triphenylphosphine by isonitrosoacetophenone leads to vinyltriphenylphosphonium salts, which undergo intramolecular wittig reaction to produce dalkyl 4-phenyl-n-hydroxypyrrole-2,3-dicarboxylates in moderate yields.
Mechanochemistry is maturing as a discipline and continuing to grow, so it is important to continue understanding the rules governing the system. In a mechanochemical reaction, the reactants are added into a vessel along with one or more grinding balls and the vessel is shaken at high speeds to facilitate a chemical reaction. The dielectric constant of the solvent used in liquid-assisted grindi...
Methyl trans-12-octadecenoate-9,10-dz was obtained from methyl threo-12,13-dihydroxy-eis-9-octadecenoate by a sequence of reactions involving formation of an ethoxydioxolane, catalytic deuteration of the double bond, and conversion of the ethoxvdioxolane group to an ethylenic bond. Methyl cisand trans-12-oct;decenoate15,15,16,16-d. and methyl cisand trans-12-octadecenoate-9 ,10,15,15,16,16-d6 w...
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