Facile synthesis of 3H,3′H-spiro[benzofuran-2,1′-isoindole]-3,3′-diones using monobromomalononitrile (MBM) as an efficient organo-brominating agent

An unexpected route for the synthesis of a new spiroheterocyclic system from ninhydrin

“…The resulting compound corresponds to a spiro[furan-2,1 0 -isoindoline] 6 product of the three-component reaction between ninhydrin 1, phenylethylamine 5, and phenylacetaldehyde (Scheme 3). The distances and bond angles within the spiroheterocyclic fragment are similar to those found in the structure of 5-methyl-3H, 12 Previous studies have demonstrated that the imine or enamine produced by the condensation between 1,3-dicarbonyl compounds and primary amines reacts with ninhydrin to form dihydroxyindenopyrrole hemiaminals. It was also demonstrated that the oxidative cleavage of certain dihydroxy-indenopyrroles and the subsequent hydrolysis and cyclization yield spiro[isobenzofuran-1,6 0 -pyrrolo[2,3-d]pyrimidine]-2 0 ,3,4 0 ,5 0 -tetraones.…”

Enolization rates control mono- versus di-fluorination of 1,3-dicarbonyl derivatives

“…For compounds 5b and 5d, k for (F) increased 3000-fold in 50% water, while 5c showed a 10 000-fold increase. Addition of formic acid (3% in MeCN) led to an increase in k for (F) of 220fold, whereas DABCO proved to be an effective agent for de-uorination of the substrate 5a (see ESI Section 3.2.1 † for related spectra, and previous reports 56,57 of bromomalonitriles acting as brominating agents). 'Spent' Selectuor™ (ClCH 2 -DABCO + BF 4 À , 0.025 mM) offered a 4-fold increase in k for (F),…”

Manganese(II)‐Mediated Domino Annulation Reaction of Vinyl Azides and 4‐Hydroxycoumarin: A Stereoselective Synthesis of Spirobenzofuranone‐lactams

“…(1)] or treatment with a brominating agent, MBN, initiating annulation [Scheme , Eq. (2)] . Very recently, Liu and co‐workers reported a CuI‐catalyzed approach for the synthesis of spirofuranone‐lactams via an alkene trifluoromethylation initiated remote α‐azidation of carbonyl compounds [Scheme , Eq.…”