96650-00-9Relevant academic research and scientific papers
Identification of the best-suited leaving group for the diastereoselective synthesis of glycidic amides from stabilised ammonium ylides and aldehydes
Herchl, Richard,Stiftinger, Martin,Waser, Mario
supporting information; experimental part, p. 7023 - 7027 (2011/11/04)
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%.
Ammonium ylides for the diastereoselective synthesis of glycidic amides
Waser, Mario,Herchl, Richard,Mueller, Norbert
, p. 2170 - 2172 (2011/04/16)
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.
Manganese-promoted regioselective ring-opening of 2,3-epoxy acid derivatives: a new route to α-hydroxy acid derivatives
Concellon, Jose M.,Bernad, Pablo L.,Rodriguez-Solla, Humberto,Diaz, Pamela
experimental part, p. 2178 - 2184 (2009/12/31)
A simple and general methodology directed towards the synthesis 3-aryl-2-hydroxy amides, or esters with total regioselectivity from the easily available 2,3-epoxy amides or esters, promoted by active manganese is described. Utilizing enantiopure epoxy amides as starting materials, the corresponding 3-aryl-2-hydroxy amides in enantiopure form are also available. Some synthetic applications of selected examples of 3-aryl-2-hydroxy carboxylic acid derivatives are shown. A mechanism has been proposed to explain this novel reaction.
Diastereoselective darzens condensations of α-haloamides: Influence of aryl substituents on diastereoselectivity
North, Michael,Pizzato, Francesca
experimental part, p. 552 - 556 (2010/04/23)
N, N-Diaryl α-haloamides undergo Darzens condensations with aldehydes induced by metal hydroxides. The diastereoselectivity of epoxide formation is strongly influenced by the electronic properties of the arylamide, which can be rationalised on the basis of the acidity of the substrate hydrogens and hence on reaction occurring under kinetic or thermodynamic control.
Sequenced elimination-reduction and elimination-cyclopropanation reactions of 2,3-epoxyamides promoted by samarium diiodide. Synthesis of 2,3-dideuterioamides and cyclopropanamides
Concellón, José M.,Huerta, Mónica,Bardales, Eva
, p. 10059 - 10065 (2007/10/03)
An easy and general sequenced elimination/reduction or elimination/ cyclopropanation process promoted by samarium diiodide or/and CH 2I2/Sm provide an efficient method for synthesising 2,3-dideuterioamides 3 or cyclopropanamides 8, respectively. The transformations take place in high yields and with total or high selectivity from the easily available 2,3-epoxyamides. Graphical Abstract
Synthesis of Aromatic (E)- or (Z)-α,β-Unsaturated Amides with Total or Very High Selectivity from α,β-Epoxyamides and Samarium Diiodide
Concellon, Jose M.,Bardales, Eva
, p. 9492 - 9495 (2007/10/03)
Highly stereoselective synthesis of aromatic α,β-unsaturated amides was achieved by treatment of aromatic α,β-epoxyamides with samarium diiodide. The starting compounds 1 and 3 are easily prepared by the reaction of enolates derived from α-chloroamides wi
Unusual reductive cleavage of 3-aryl-2,3-epoxyamides by using samarium diiodide. Synthesis of 3-aryl-3-deuterio-2-hydroxyamides with total regioselectivity
Concellón, José M.,Bardales, Eva,Gómez, Cecilia
, p. 5323 - 5326 (2007/10/03)
Ring-opening of 3-aryl-2,3-epoxyamides 1 was achieved by using samarium diiodide and D2O, yielding 3-aryl-3-deuterio-2-hydroxyamides 2 with total regioselectivity. The starting compounds 1 were easily prepared by reaction of the corresponding lithium or potassium enolates of α-chloroamides with aldehydes or ketones. When the reaction was carried out in the presence of H2O instead of D2O, the corresponding 3-aryl-2-hydroxyamides were isolated. The treatment of enantiopure 3-aryl-2,3-epoxyamides afforded optically active 3-aryl-2-hydroxyamides.
Catalytic sulfur ylide reactions: Use of diazoacetamides for the diastereoselective synthesis of glycidic amides
Aggarwal, Varinder K.,Blackburn, Paul,Fieldhouse, Robin,Jones, Ray V. H.
, p. 8517 - 8520 (2007/10/03)
Diazoacetamides react with aldehydes in the presence of catalytic quantities of Cu(acac)2 (5 mol%) and tetrahydrothiophene (20 mol%) to give glycidic amides in good yields and high diastereoselectivity.
A stereocontrolled approach to electrophilic epoxides
Meth-Cohn, Otto,Moore, Clive,Taljaard, Heinrich C.
, p. 2663 - 2674 (2007/10/02)
Lithium t-butyl hydroperoxide (easily generated by addition of an alkyl-lithium to anhydrous t-butyl hydroperoxide in THF solution) is a powerful reagent for the epoxidation of electrophilic alkenes at -20 to 0 °C under full stereocontrol. Thus αβ-unsaturated esters, sulphones, sulphoximines, and amides are readily epoxidised with complete regio- and stereo-specificity and with considerable chiroselectivity (20-100%) when appropriate chiral auxiliaries such as menthyl, 8-phenylmenthyl, or a camphor-sulphonamide derivative are used. Asymmetric αβ-unsaturated sulphoximines undergo epoxidation with 100% diastereoselectivity. The only exceptions to stereocontrol noted are heavily substituted maleate esters such as di-t-butyl maleate. The αβ-epoxy amides are shown to be valuable sources of the corresponding epoxy ketones by treatment with an organolithium, allowing a stereo- and chemoselective entry in high yield to these useful intermediates.
