Reactivity of 2-Halo-2H-azirines. 1. Reactions with Nucleophiles (original) (raw)
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Synthesis and reactivity of 2-halo-2H-azirines towards nucleophiles
Tetrahedron Letters, 2000
Nucleophilic substitution reactions of 2-halo-2H-azirine with potassium phthalimide and aniline allowed the preparation of new substituted 2H-azirines. The reactions of 2-bromo-3-phenyl-2H-azirine-2-carboxylate with methylamine led to the synthesis of a-diimines and from the reaction with water, a 3-oxazoline was obtained.
Synthesis of 2-halo-2H-azirines
Tetrahedron, 2001
AbstractÐa-Oxophosphonium ylides react with N-chlorosuccinimide, N-bromosuccinimide and N-iodosuccinimide in the presence of azidotrimethylsilane giving the corresponding haloazidoalkenes which were completely converted to the 2-halo-2H-azirines on heating in heptane. q Scheme 1.
Reactivity of 2-halo-2H-azirines. Part 3: Dehalogenation of 2-halo-2H-azirine-2-carboxylates
Tetrahedron, 2003
The dehalogenation of 2-halo-3-phenyl-2H-azirine-2-carboxylates is described. Using sodium borohydride and tributyltin hydride 3-phenyl-2H-azirine-2-carboxylates were obtained in moderate yields. The synthesis of a new 2-bromo-2H-azirines with a chiral auxiliary, 10-phenylsulfonylisobornyl 2-bromo-3-phenyl-2H-azirine-2-carboxylate, is reported. Its dehalogenation led to 10-phenylsulfonylisobornyl 2H-azirine-2-carboxylate as single stereoisomer together with the formation of 10-phenylsulfonylisobornyl acetate.
Synthetic approaches toward the bi(2H-azirine) system
J Org Chem, 1979
Three different approaches toward the synthesis of the bi(2H-azirine) system (2) were investigated. The first route is based on a modified Neber reaction in which the bis(trimethy1hydrazonium) salt of 2,3-dimethyl-1,4-diphenyl-1,4-butanedione was treated with base. No indication of any bi(2H-azirine) could be detected in this reaction. In a second approach, the reaction of 2-styryl-3-phenyl-2H-azirine with iodine azide was investigated. The major product isolated from this reaction was l-phenyl-5-( 1-azidocinnamy1)tetrazole. Subsequent studies with model systems showed that the reaction of iodine azide with 3-phenyl-2-substituted 2H-azirines gives azidotetrazoles in moderate yield. The reaction is believed to involve the addition of iodine azide across the C-N double bond followed by ring opening of a transient iodoaziridine. Attack of azide on the incipient carbonium ion followed by electrocyclization of the azidoimine formed readily accommodates the formation of the tetrazole ring. The third approach utilized for the synthesis of the bi(2H-azirine) system involved an attempt to dimerize 2-chloro-2H-azirines with activated metals or by electrolysis. A sample of 2-chloro-2-methyl-2-phenyl-2H-azirine was found to rearrange to the isomeric 2-chloro-3-methyl-2-phenyl-2H-azirine in solution. This rearrangement is consistent with the intermediacy of an azacyclopropenyl ion-chloride pair. All attempts at dimerization proved unsuccessful.
Synthesis of oxazolinyl aziridines
Tetrahedron Letters, 1999
Aziridinyllithiums 4a and 4b, which are stable at low temperature, can be generated by deprotonation of 3a and 3b. Oxazolinyl aziridines 5a-j and 6a-b have been prepared by the reaction of oxazolinyl aziridinyllithiums 4a and 4b with electrophiles. Aziridines 6c and 6d were, instead, synthesized by a Darzens-like reaction from 2-(1-chloroethyl)-2-oxazoline lb.
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...