1,3 Dipolar cycloadditions of azomethine ylides with aromatic aldehydes. syntheses of 1-oxapyrrolizidines and 1,3-oxazolidines (original) (raw)
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Mediterranean Journal of Chemistry, 2013
Phtaloylimidophenylalanyl-2-hydroxymethylaziridine has been used as a starting material to yield azomethine ylide through thermal opening and was then involved into 1,3-dipolar cycloaddition reactions. Different five-membered adducts were obtained and were fully identified. The latter might be considered useful starting materials for further functionalization to provide novel compounds of biological interest.
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Bulletin des Sociétés Chimiques Belges, 1994
Azomethine ylides generated from 5-(alkoxycarbonylmethyl)phenanthridinium cations were studied in 1,3dipolar cycloadditions with dimethyl maleate and dimethyl fumarate as dipolarophiles. The cycloadducts with the pyrrolidino[l,2-f]phenanthridine skeleton easily underwent dehydrogenation. The structure of products was determined by X-ray, NMR and MS.
Azomethine Ylides—Versatile Synthons for Pyrrolidinyl-Heterocyclic Compounds
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Azomethine ylides are nitrogen-based three-atom components commonly used in [3+2]-cycloaddition reactions with various unsaturated 2π-electron components. These reactions are highly regio- and stereoselective and have attracted the attention of organic chemists with respect to the construction of diverse heterocycles potentially bearing four new contiguous stereogenic centers. This review article complies the most important [3+2]-cycloaddition reactions of azomethine ylides with various olefinic, unsaturated 2π-electron components (acyclic, alicyclic, heterocyclic, and exocyclic ones) reported over the past two decades.
Beilstein journal of organic chemistry, 2015
Strained azirinium ylides derived from 2H-azirines and α-diazoketones under Rh(II)-catalysis can undergo either irreversible ring opening across the N-C2 bond to 2-azabuta-1,3-dienes that further cyclize to 2H-1,4-oxazines or reversibly undergo a 1,5-cyclization to dihydroazireno[2,1-b]oxazoles. Dihydroazireno[2,1-b]oxazoles derived from 3-aryl-2H-azirines and 3-diazoacetylacetone or ethyl diazoacetoacetate are able to cycloadd to acetyl(methyl)ketene generated from 3-diazoacetylacetone under Rh(II) catalysis to give 4,6-dioxa-1-azabicyclo[3.2.1]oct-2-ene and/or 5,7-dioxa-1-azabicyclo[4.3.1]deca-3,8-diene-2-one derivatives. According to DFT calculations (B3LYP/6-31+G(d,p)), the cycloaddition can involve two modes of nucleophilic attack of the dihydroazireno[2,1-b]oxazole intermediate on acetyl(methyl)ketene followed by aziridine ring opening into atropoisomeric oxazolium betaines and cyclization. Azirinium ylides generated from 2,3-di- and 2,2,3-triaryl-substituted azirines give ris...