904048-56-2Relevant academic research and scientific papers
Diastereoselective t-reaction of 1-alkyl-5-(5-nitro-2- n-morpholino- benzylidene)barbituric acids in the solid state: Synthesis of 1-alkyl-2,4,6-trioxoperhydropyrimidino-5- spiro -10'-(7'-nitro-1',3',4',9',10', 10a'-hexahydro-2'-oxa)-4a'-azaphenanthrenes and their 2'-thia analogues
Krasnov, Konstantin A.,Khrustalev, Victor N.
, p. 3975 - 3982 (2014)
1-Alkyl-5-(5-nitro-2-N-morpholinobenzylidene) barbituric acids undergo tert-amino effect reactions (T-reactions) yielding 1-alkyl-2,4,6- trioxoperhydropyrimidino-5-spiro-10'-(7'-nitro-1',3',4',9',10', 10a'-hexahydro-2'-oxa)-4a'-azaphenanthrene derivatives as a mixture of (S*,S*)- and (S*,R*)-diastereomers. A novel heterophase modification of the T-reaction is proposed, which makes it possible to afford nearly pure (S*,S*)-diastereomers in high yields, whereas rearrangement reactions in solutions usually lack stereoselectivity. To our best knowledge, this is the first example of deliberate tuning stereodirection of a T-reaction by external conditions. Using X-ray diffraction analysis, we demonstrate that this diastereoselectivity of the solid state T-reaction is due to a peculiar crystal structure of starting 5-arylidene barbiturates, which accommodates only one specific conformation fixed by a strong intramolecular C-H···π interaction.
Diastereoselective synthesis of 1-alkyl-2,4,6-trioxoperhydropyrimidine-5- spiro-3′-(1′,2′,3′,4′-tetrahydroquinolines)
Krasnov, Konstantin A.,Kartsev, Victor G.,Khrustalev, Victor N.
experimental part, p. 6054 - 6061 (2010/10/03)
Knoevenagel products formed by the condensation of N-monoalkyl barbituric acids with o-tert-amino benzaldehydes undergo tert-amino effect reactions (T-reactions) yielding 1-alkyl-2,4,6-trioxoperhydropyrimidine-5-spiro-3′- (1′,2′,3′,4′-tetrahydroquinoline) derivatives as a mixture of (S*,S*)- and (S*,R*)-diastereomers. Mostly, the major diastereomer has the S*,S*-configuration. According to X-ray diffraction data in the solid form and NOE data in solution, diastereoselectivity of the T-reactions can be associated with the structure of the Knoevenagel products whose conformation is fixed by the strong intramolecular C-H?π interaction.
