- Reactions of pyrrolidine enamines of cyclic and acyclic 3,4-dioxobutanoic acid derivatives with dimethyl acetylenedicarboxylate. A new case of atropoisomerism
-
Reaction conditions and structure of the starting enamines (cyclic or open-chain) determine greatly the final products of the title reactions. Whereas in benzene and acetonitrile, DMAD and 1 give a mixture of the diastereoisomeric dienamines 5, in methanol they afford pirrolizine 3. Enaminofuranones 2 and 10 furnish in the corresponding 'Michael adducts' 7a,b,c and 11a,b,c but fail to yield pirrolizines. It has been demonstrated that above b and c adducts differ exclusively on the arrangement of groups around a chiral axis.
- De Ancos, Begona,Carmen Maestro,Rosano Martin,Mateo, Ana I.
-
-
Read Online
- SINTESIS Y REACCIONES CON AMIDINAS DE DERIVADOS CICLICOS Y DE CADENA ABIERTA DEL ACIDO 2-BROMO-3,4-DIOXOBUTANOICO.
-
Bromination of enaminoesters 1 and 5, in appropriate conditions, affords in good yield enamines of the corresponding 2-bromo-3,4-dioxobutanoic acid derivatives 2-3 and 6 or dibromocompounds 4 and 6.The open chain enaminoesters (1-3) are more easily hydrolyzed that enaminofuranones 5 and 6.Prolongated treatment of 6 with hydrochloric acid affords the chlorinated enamine 11.The synthesis of 3-Bromo-4-hydroxy-5-methoxyfuran-2(5H)-one 10 can be achieved by bromination of 12, obtained by hydrolysis of 5.The reaction of methyl 3-bromo-4,4-dimethoxy-3-oxobutanoate with amidines is a good method for the synthesis of 5-bromo-6-(dimethoxymethyl)pyrimidin-4(3H)-ones substituted at 2 position.Under the same conditions the reaction of furanone 10 with benzamidine does not lead to the corresponding imidazoline. - Keywords: enaminoesteres, 4-aminofuranonas, bromacion, hidrolisis, pirimidonas.
- Ancos, B. De,Delgado, F.,Martin, M. R.
-
p. 413 - 420
(2007/10/03)
-
- REACTIVIDAD DE ENAMINAS TERCIARIAS DE DERIVADOS CICLICOS Y DE CADENA ABIERTA DEL ACIDO 3,4-DIOXOBUTANOICO
-
Enaminoester 1a and enaminofuranone 2 with iodomethane, 2-chloro-1,3-dithiane and phenyldiazonium tetrafluoroborate afford the products resulting from electrophilic attack on the C-α to the carbonyl group.However, acyl chlorides with 1a yield O-acylated products.The above reactives and 1a give the corresponding products of enamino group hydrolysis.Enamines 1a and 1b react with dichlorocarbene, generated in phase transfer conditions, to yield chlorofuranones 17a and 17b dimethoxyacetamides 18a and 18b . p-Nitrophenylazide affords 1,2,3-triazol 20 in good yield by reaction with enaminoester 2; but when reacts with 2 gives in small amount the azoderivative 21.It is noteworthy that in the above cycloaddition reactions, the open-chained enaminoester 1a is much more reactive than the enaminofuranone 2.Palabras clave: Enaminoester, enaminolactona, alquilacion, acilacion, cicloadicion, diclorocarbeno, triazol.
- Ancos, B. de,Farina, F.,Maestro, M. C.,Martin, M. R.
-
p. 132 - 141
(2007/10/02)
-
