Stereoselective intramolecular hetero Diels–Alder reactions of 1-oxa-1,3-butadienes: a novel approach for the synthesis of complex annulated uracils
作者:Ipsita Devi、Pulak J. Bhuyan
DOI:10.1016/j.tetlet.2004.08.072
日期:2004.10
The intramolecular hetero Diels–Alderreactions of 1-oxa-1,3-butadienes 4, obtained from salicylaldehyde 1 via O-allylation followed by Knoevenagel condensation with barbituric acids 3 in the presence of hydrochloric acid as catalyst, affords the tetracyclic uracil derivatives 5 and 6 in a stereoselective manner and high overall yields.
Hydride transfer reactions of 5-(2-alkohybenzylidene) barbituric acids: Synthesis of 2,4,6-trioxoperhydropyrimidine-5-spiro-3′-chromanes
作者:Konstantin A. Krasnov、Pavel V. Dorovatovskii、Yan V. Zubavichus、Tatiana V. Timofeeva、Victor N. Khrustalev
DOI:10.1016/j.tet.2016.12.045
日期:2017.2
thermal cyclization of 5-(2-phenoxymethylphenyl-methylene)barbituricacid and its derivatives affords 2,4,6-trioxoperhydropyrimidine-5-spiro-3′-chromanes. The reactions require no catalysts and proceed at temperatures from 118 to 240 °C depending on the substrate activity. These cyclization reactions are analogous to T-reactions of tertiary amines involving the hydride transfer.