One-pot Four Component Reaction of Unsymmetrical 1-Methylbarbituric Acid with BrCN and Various Aldehydes in the Presence of Et₃N and/or Pyridine

Abstract

ABSTRACT. Reaction of 1-methylpyrimidine-(1H,3H,5H)-2,4,6-trione (1-MBA 1) as an unsymmetrical barbituric acid with cyanogen bromide and various aldehydes in the presence of triethylamine and/or pyridine afforded diastereomeric mixtures of new class of heterocyclic stable 5-aryl-1,1'-dimethyl-and 5-aryl-3,1'-dimethyl-1H,1'H-spiro[furo[2,3-d]pyrimidine-6,5'-pyrimidine]2,2',4,4',6'(3H,3'H,5H)-pentaones which are dimeric forms of 1-methyl barbiturate at the range of 0 o C to room temperature. In the reaction of some aldehydes with 1-MBA and BrCN were afforded a mixture of diastereomers. Another two aldehydes such as 4-cyano-and 2-hydroxybenzaldehydes gave exclusively two diastereomers in which binded to the salt of triethylammonium hydrobromide by intermolecular H-bond in ratio of 1:1. 4-Hydroxybenzaldehyde and 2-pyridinecarbaldehyde gave exclusively one diastereomer under the same condition. Aldehydes possessing strong electron-donor were produced exclusively two geometric isomers of Knoevenagel adduct (E-and Z-isomers). The structures of compounds were deduced by 1 H NMR, 13 C NMR and FT-IR spectroscopy. Mechanism of the formation is discussed.

One‐pot, fast cyclopropanation reaction of indandione with various aldehydes in the presence of cyanogen bromide and trimethylamine

“…The structures of salts 4a '– 4b ' are shown in Figure . According to our previous reported mechanisms for the formation of the salts 10 and 11 , a representative proposed reaction mechanism for the formation of salt 4a ' is shown in Scheme . The salt of 7a ' was formed in the presence of Et 3 N and in the absence of BrCN (path b ).…”

Regioselective One‐pot Synthesis of New Unsymmetric Spiro Dihydrofurans in the Reaction of Mixed Two Different Cyclic β‐Dicarbonyl Compounds with BrCN and Aldehydes in the Presence of Et3N

“…18,20,21,23 The structures of 13a¢-e¢ have also been reported by the same authors. [18][19][20][21]23 In these types of reactions in the presence of BrCN, the only exception of b-dicarbonyl compounds for cyclopropanation (C-attack) are the malononitrile 26 and Meldrum's acid 27 under the same condition. The novelty and advantagues of the present research work is the selective formation of sole spiro dihydrofuran from among of four possible products (Scheme 2).…”

“…16 Yan et al reported the synthesis of spiro dihydrofurans using DABCO catalysis. 17 Recently we have reported the one-pot reaction of an aldehyde with a cyclic b-dicarbonyl compound in the presence of cyanogen bromide (BrCN) and triethylamine [18][19][20][21] and L-(+)-tartaric acid (TA). 22 The one-pot reaction of aromatic dialdehydes with (thio)barbituric acids in the presence of BrCN and triethylamine have been reported by our research group.…”

Review on synthetic approaches towards barbituric acids‐based furo[2,3‐d]pyrimidines

“…4‐Hydroxybenzaldehyde and 2‐pyridinecarbaldehyde yield exclusively one diastereomer under the same condition. Aldehydes possessing strong electron‐donor were produced exclusively by two geometric isomers of Knoevenagel adduct ( E ‐ and Z ‐isomers) [58].…”