نتایج جستجو برای: thiocarbonyl ylides
تعداد نتایج: 930 فیلتر نتایج به سال:
The manuscript is an update to the earlier Science of Synthesis contribution describing methods for the synthesis and new applications of thiocarbonyl S-oxides (sulfines) and thiocarbonyl S-imides. In general, thiocarbonyl S-oxides are more stable and in many instances they can be isolated in substance. The in situ generated thiocarbonyl S-imides are efficient ‘sulfur transferring agents’ via t...
In this paper, we describe studies on the cyclopropanation of Michael acceptors with chiral sulfur ylides. It had previously been found that semi-stabilized sulfonium ylides (e.g., Ph-stabilized) reacted with cyclic and acyclic enones and substituted acrylates with high ee and that stabilized sulfonium ylides (e.g., ester-stabilized) reacted with cyclic enones again with high ee. The current st...
Highly soluble dimedone-derived o-alkoxyphenyliodonium ylides have been prepared and characterized by single crystal X-ray diffraction. These new iodonium ylides are useful reagents for the preparation of oxazole derivatives by reaction with carbodiimides.
the reaction between vinylene trithiocarbonate and chlorosulfonyl isocyanate proceeds by initial attack of thiocarbonyl on the isocyanate carbon.
The bond dissociation enthalpies (BDEs) of sulfur and selenium ylides have been estimated by applying MP2/6-311++G(3df,2p)//MP2/6-31G(d,p), G3, and other computational methods. Computed sulfoxide bond enthalpies were compared to experimental results to ensure the reliability of the computational methods before extending to related compounds. The examined ylides include the following: sulfoxides...
The Stevens and Sommelet–Hauser rearrangement of ammonium ylides are known as useful transformations for organic synthesis because they convert a readily accessible C–N bond into a new C–C bond. The Stevens rearrangement has been widely used for the asymmetric synthesis of α-amino acid derivatives, whereas the Sommelet–Hauser rearrangement is much less common because the Sommelet–Hauser rearran...
We provide a comprehensive account of the 1,3-dipolar cycloaddition reactions of azomethine ylides with carbonyl dipolarophiles. Many different azomethine ylides have been studied, including stabilized and non-stabilized ylides. Of the carbonyl dipolarophiles, aldehydes including formaldehyde are the most studied, although there are now examples of cycloadditions with ketones, ketenes and carbo...
In comparison to the use of sulfur ylides, the use of ammonium ylides for the synthesis of epoxides is significantly less developed. As a part of our systematic investigations concerning the use of amide-stabilised ammonium ylides for the synthesis of glycidic amides we have focused on the identification of the best-suited amino leaving group for this purpose. Whereas tertiary amines like quinu...
The first examples of azomethine ylides derived from allylic amine and glyoxal precursors are reported. The condensation of primary allylic and α-aryl amines with glyoxylates or α-aryl glyoxals affords conjugated azomethine ylides that undergo facile [3 + 2] cycloaddition, providing 5-alkenyl pyrrolidine cycloadducts that cannot be accessed through the classical use of amino esters as ylide pre...
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