A green synthesis of unsymmetrical triarylmethanes via indium (III) triflate catalyzed Friedel Crafts alkylation of o-hydroxy bisbenzylic alcohols under solvent free conditions. Issue 2 (10th January 2018)

• Record Type: Journal Article
• Authors: Mondal, Sankalan; Roy, Deblina; Jaiswal, Manoj Kumar; Panda, Gautam
• Is Part Of: Tetrahedron letters. Volume 59:Issue 2(2018)
• Page Start: 89
• Page End: 93
• Publication Date: 2018-01-10
• Subjects: Unsymmetrical triarylmethanes -- Green synthesis and green metrics -- Solvent free reaction, atom economy; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2017.11.049
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Friedel Crafts alkylation under solvent free conditions. Air and moisture tolerant, open-flask condition with water as by product. Indium triflate could be recycled and reused up to 5 times. Abstract: Using indium (III) triflate as a mild Lewis acid catalyst, the Friedel Crafts alkylation of o -hydroxy bisbenzylic alcohols with aromatic/heteroaromatic arenes under solvent free conditions was achieved to give the corresponding unsymmetrical triarylmethanes in high yields (up to 80% yield). Calculation of the different green metrics for the above reaction revealed it to have high atom economy (94–96%), high reaction mass efficiency (66–77%) and high carbon efficiency (70–80%). The Lewis acid was found to be air and moisture tolerant. The protocol was found to be operationally simple and can be carried out in an "open-flask" leaving behind water as the sole by product. Gratifyingly the Lewis acid catalyst could be recycled and reused up to 5 catalytic cycles without compromising much on the yield thus further highlighting the importance of the protocol.