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

Abstract

Crossed one-pot reaction of mixed cyclic b-dicarbonyl with various aldehydes in the presence of cyanogen bromide and triethylamine leads to the selective and efficient formation of crossed new unsymmetrical spiro dihydrofurans at room temperature. The products were obtained in good to excellent yields. Structure elucidation was carried out by 1 H NMR, 13 C NMR, FT-IR spectroscopy, Mass analyses and X-ray crystallography technique. A proposed mechanism was discussed for the formation of products. ArticleNoroozi Pesyan et al. Scheme 1 One-pot cascade selective reaction of the mixture of an aldehyde (4a-4e) and two different cyclic b-dicarbonyl compounds Scheme 2 One-pot cascade selective reaction of 1 and 2 with 4 (top), 2 and 3 with 4 (bottom) in the presence of BrCN and triethylamine Scheme 3 Mechanism of the formation of 6a as a representative

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 ).…”

A review of the synthetic strategies toward spirobarbiturate-fused 3- to 7-membered rings

“…Furthermore, the same reaction using 1,3-dimethyl barbituric and dimedone 16 with aldehyde resulted in the synthesis of another type of spirobarbiturate scaffold (Scheme 13). 50 In 2012, Vereshchagin et al described the electrocatalytic construction of spiro[furo [2,3-d]pyrimidine-6,50-pyrimidine] pentones from barbiturate-based olefins 1 and 1,3-dimethyl barbituric acid 6 using sodium bromide in an undivided cell. In this bromide-anion-mediated electrocatalytic strategy, a catalytic amount of NaBr was used instead of an equivalent amount of bromine to access the α-bromo-active methylene intermediate (Scheme 14).…”

“…Furthermore, the same reaction using 1,3-dimethyl barbituric and dimedone 16 with aldehyde resulted in the synthesis of another type of spirobarbiturate scaffold (Scheme 13). 50…”

4‐Methyl morpholinium bis‐(thio)barbiturates: Synthesis, structure, anticancer evaluation, and CoMFA study

“…[ 15 ] One‐pot reaction of (thio)barbituric acids with aldehydes and cyanogen bromide yield spiro furo[2,3‐ d ] pyrimidines. [ 16–21 ]…”