Cycloisomerization of Allene–Enol Ethers under Bi(OTf)3 Catalysis

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

We describe the use of bismuth(III) triflate as an efficient and environmentally friendly catalyst for the Nazarov reaction of aryl vinyl ketones, leading to the synthesis of 3-aryl-2-ethoxycarbonyl-1-indanones and 3-aryl-1-indanones. By changing the temperature and reaction time, it was possible to modulate the reactivity, allowing the synthesis of two distinct product classes (3-aryl-2-ethoxycarbonyl-1-indanones and 3-aryl-1-indanones) in good to excellent yield. The reaction did not require additives and was insensitive to both air and moisture. Preliminary biological evaluation of some indanones showed a promising profile against some human cancer line cells.

Bsi(OTf)3-mediated tandem annulation of 1-aryl isochroman-3-ones with oxygenated arenes: one-pot synthesis of polyoxygenated homotriptycenes

Bi(OTf)3 (bismuth triflate)-mediated one-pot tandem annulation of oxygenated 1-aryl isochroman-3-ones with oxygenated arenes provides polyoxygenated homotriptycenes in moderate to good yields in MeNO2 at reflux (101 °C) for 10 h under an air atmosphere and easy-operational conditions via intermolecular and intramolecular Friedel-Crafts type procedures. A plausible mechanism is proposed and discussed. This protocol provides a highly effective ring-closure via three carbon-carbon (C-C) bond formations.

Heterogeneous catalysis for the tandem cyclisation of unsaturated alcohols

A methodology for the tandem cycloisomerisation of doubly unsaturated alcohols using Amberlyst-15 was developed.

Acid-catalysed intramolecular addition of β-ketoesters to 1,3-dienes

1,3-Dienyl β-keto esters are cyclised into bicyclolactones using the Bi(OTf)₃/TfOH catalytic system. This reaction represents a rare case of simultaneous C-C and C-O bond formation at positions 1 and 3 of a 1,3-diene. Application to the synthesis of ramulosin is presented.

Rapid Asymmetric Synthesis of Disubstituted Allenes by Coupling of Flow-Generated Diazo Compounds and Propargylated Amines

We report herein the asymmetric coupling of flow‐generated unstabilized diazo compounds and propargylated amine derivatives, using a new pyridinebis(imidazoline) ligand, a copper catalyst and base. The reaction proceeds rapidly, generating chiral allenes in 10–20 minutes with high enantioselectivity (89–98 % de/ee), moderate yields and a wide functional group tolerance.

Bismuth(iii) triflate-catalysed tandem cyclisations towards complex polycyclic ethers

A series of complex polycyclic ethers have been synthesised under very mild conditions using a low catalyst loading of bismuth(iii) triflate.