Identification of the best-suited leaving group for the diastereoselective synthesis of glycidic amides from stabilised ammonium ylides and aldehydes.
نویسندگان
چکیده
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 quinuclidine or cinchona alkaloids were found to be not suited for epoxide formation, trimethylamine was found to be the leaving group of choice, yielding trans-glycidic amides in excellent yields of > 90%.
منابع مشابه
Ammonium ylides for the diastereoselective synthesis of glycidic amides.
A highly trans-selective protocol for the synthesis of glycidic amides was developed. This approach gave access to oxiranes by reacting stabilised ammonium ylides bearing an α-carbonyl group and aromatic aldehydes in moderate to good yields.
متن کاملAmmonium ylides for the diastereoselective synthesis of glycidic amidesw
The (dia-)stereoselective synthesis of glycidic amides and esters has attracted considerable interest over the last few decades mainly due to the high potential of these compounds as synthetically useful intermediates in a variety of organic syntheses. Ylides have proven to be very powerful synthons for the formation of epoxides providing alternatives to the oxidation of a,b-unsaturated carbony...
متن کاملAsymmetric syntheses of three-membered heterocycles using chiral amide-based ammonium ylides† †Electronic supplementary information (ESI) available: Experimental and computational details, characterization of new compounds, and copies of NMR spectra. CCDC 1023711 and 1030561. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ob02318h Click here for additional data file. Click here for additional data file.
The use of carbonyl-stabilised ammonium ylides to access chiral glycidic amides and the corresponding aziridines has so far been limited to racemic trans-selective protocols. We herein report the development of an asymmetric approach to access such compounds with high levels of stereoselectivity using easily accessible chiral auxiliary-based ammonium ylides. The use of phenylglycinol as the chi...
متن کاملDelineation of the factors governing reactivity and selectivity in epoxide formation from ammonium ylides and aldehydes.
Diastereoselectivity in reactions of aryl-stabilised ammonium ylides are highly sensitive to the nature of the amine and the ylide substituent. DFT calculations are consistent with a mechanism in which reversibility in betaine formation [despite the high energy (and therefore instability) of ammonium ylides] is finely balanced due to the high barrier to ring closure.
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Sodium acetate catalyzed the multi-component reaction of acetophenone, aromatic aldehydes, and acetoacetanilide in the water-ethanol mixture (1:1) at ambient temperature via Claisen-Schmidt condensation results in the formation of highly substituted cyclohexenones in 89–98% yields. The developed efficient catalytic approach to the substituted cyclohexenones – the promising ...
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ورودعنوان ژورنال:
- Organic & biomolecular chemistry
دوره 9 20 شماره
صفحات -
تاریخ انتشار 2011