261639-91-2Relevant articles and documents
Mechanism of the reaction of amines with 5-[(Aryl- or Alkylamino) hydroxymethylene]-2,2-dimethyl-1,3-dioxane-4,6-diones in the presence of chlorotrimethylsilane (Me3SiCl)
Janikowska, Karolina,Makowiec, Slawomir,Rachon, Janusz
, p. 978 - 984 (2013)
Addition of chlorotrimethylsilane (Me3SiCl) to the mixture of a carbamoyl-substituted Meldrum's acid, i.e., a 5-[(arylamino)hydroxymethylene]-2, 2-dimethyl-1,3-dioxane-4,6-dione of type 1 and a secondary amine as nucleophile strongly accelerated the rate of their reaction. The reason for this phenomenon observed, during our previous research, remained, however, unclear. To elucidate the mechanism of this reaction, we assumed and verified three possible pathways for the action of Me3SiCl (cf. Scheme 2): The acceleration of the reaction is caused i) by formation of a O-trimethylsilylated Meldrum's acid of type 2, ii) by the silylated amine 3, or iii) by the presence of HCl liberated from Me3SiCl. The performed experiments revealed that the faster course of reaction is caused by the formation of N-trimethylsilylated amines of type 3. Copyright
One-step synthesis of β-lactams with retro-amide side chain
Janikowska, Karolina,Pawelska, Natalia,Makowiec, Sawomir
scheme or table, p. 69 - 72 (2011/02/24)
A one-pot synthesis for the preparation of 1,4-disubstituted 2-oxoazetidine-3-carboxylic acid amides was developed. 5-[(N-substituted-amino) (hydroxy)methylene] Meldrum's acids act as a source of ketenes that react with aldimines in boiling toluene to giv
Enols of carboxylic acid amides with β-electron-withdrawing substituents
Mukhopadhyaya, Jayanta Kumar,Sklenak, Stepan,Rappoport, Zvi
, p. 1325 - 1336 (2007/10/03)
The effect of stabilizing enols of carboxamides by several two β- electron-withdrawing substituents was studied with the R1R2CHCONHPh systems. When R1R2CH2 = Meldrum's acid (MA), the solid-state structure is that of the enol R1R2C=C(OH)NHPh (7). In CDCl3 solution the structure is 7, but there may be some exchange on the NMR time scale with a tautomer. B3LYP/6-31G** calculations show a significant preference for the enol R1R2C=C(OH)NH2 (12a) (R1R2C = MA moiety) and a small preference for (MeO2C)2C=C(OH)NHPh (11b) over the amide structures. However, solid 11 has the amide structure (MeO2C)2CHCONHPh (11a). NMR spectra in CDCl3 show >90% of 11a, but a minor species, probably 11b, is also present. In DMSO this species is not observed. The analogous dimedone-substituted anilide 10 exists both in the solid state and in solution as an enol of a ring carbonyl. Calculations show that HC(CO2Me)3 has a lower energy than its tautomeric enol. The effects of the push-pull structures of the enols on structural and spectrometric parameters, of the β-substituents, of the planarity of the system, of the acid derivative group (ester or anilide), and of the solvent as enol-stabilizing factors are discussed. Destabilization of the acid form contributes to the increased relative stability of the enols.
