Microwave-accelerated and efficient synthesis of structurally diverse N-(2,2-diphenylvinyl)-β-oxoamides

Abstract

N-(2,2-Diphenylvinyl)-β-oxoamides are both the structural moiety of biologically active compounds and important synthetic intermediates. Structurally diverse N-(2,2-diphenylvinyl)-β-oxoamides are prepared efficiently from 2-diazo-1,3-dicarbonyl compounds and N-alkyl-2,2-diphenylaziridines via an electrophilic ring opening...

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

“…A new and efficient synthetic method for the synthesis of oxazolines has been developed with alkyl 2-diazo-3-oxoalkanoates and 2-arylaziridines as starting materials. Alkyl Alkyl 2-diazo-3-oxoalkanoates 1 were synthesized by referring our previous procedure [22,23]. Their analytic data are identical to previously reported ones 1a,b [23], 1c,d [24], 1e,g [25], 1f [26], 1h [27] and 1i [28].…”

“…On the basis of the experimental results and previous reports [21,22], the reaction mechanism is rationalized as following (Scheme 3). Under microwave heating, diazo esters 1 undergo a Wolff rearrangement to generate ethoxycarbonylketenes A by loss of nitrogen.…”

“…Alkyl 2-diazo-3-oxoalkanoates 1 were synthesized by referring our previous procedure [ 22 – 23 ]. Their analytic data are identical to previously reported ones 1a , b [ 23 ], 1c , d [ 24 ], 1e , g [ 25 ], 1f [ 26 ], 1h [ 27 ] and 1i [ 28 ].…”

“…considered as the NCC structural fragment after ring-opening and have been applied in the synthesis of aziridine-imine-containing chiral tridentate ligands [20], 2-alkylideneoxazolidines [21], and N-vinylamides [22]. We envisioned that the reaction of ethoxycarbonylketenes and aziridines can be applied for the synthesis of ethyl 2-(oxazolin-2-yl)alkanoates.…”

“…They mainly include (1) cyclization of 2-amidoethyl halides or sulfonates, which are prepared from carboxylic acid derivatives and vicinal amino alcohols [ 8 – 10 ] ( Scheme 1a ); (2) direct condensation of carboxylic acid derivatives or nitriles with vicinal amino alcohols [ 13 – 15 ] ( Scheme 1a ); (3) oxidative condensation of aldehydes with vicinal amino alcohols [ 16 ] ( Scheme 1b ); (4) cyclization of N -allylamides in the presence of electrophilic reagents or radical initiators or catalysts [ 17 ] ( Scheme 1c ); (5) direct synthesis from alkenes and amides or nitriles in the presence of electrophilic reagents [ 18 – 19 ] ( Scheme 1d ). Aziridines can be considered as the NCC structural fragment after ring-opening and have been applied in the synthesis of aziridine-imine-containing chiral tridentate ligands [ 20 ], 2-alkylideneoxazolidines [ 21 ], and N -vinylamides [ 22 ]. We envisioned that the reaction of ethoxycarbonylketenes and aziridines can be applied for the synthesis of ethyl 2-(oxazolin-2-yl)alkanoates.…”