Computed Properties of Br3InIn 2018 ,《A five-component Biginelli-Diels-Alder cascade reaction》 appeared in Frontiers in Chemistry (Lausanne, Switzerland). The author of the article were Maskrey, Taber S.; Frischling, Madeline C.; Rice, Mikhaila L.; Wipf, Peter. The article conveys some information:
A new multi-component condensation was discovered during the reaction of urea, β-keto ester and formaldehyde. In the presence of catalytic indium bromide, a Biginelli dihydropyrimidinone intermediate such as I [R1 = Et, Me, Bn; X = O, S] was further converted to a five-component condensation product such as II [R1 = Me, Et, allyl, Bn; X = O, S] through a formal hetero Diels-Alder reaction. The product structure was confirmed by NMR and NOE anal. and the proposed stepwise mechanism was supported by the reaction of the Biginelli intermediate with Et 2-methylene-3-oxobutanoate. In the part of experimental materials, we found many familiar compounds, such as Indium(III) bromide(cas: 13465-09-3Computed Properties of Br3In)
Indium(III) bromide(cas: 13465-09-3) is used in organic synthesis as a water tolerant Lewis acid. It efficiently catalyzes the three-component coupling of β-keto esters, aldehydes and urea (or thiourea) to afford the corresponding dihydropyrimidinones.Computed Properties of Br3In
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary