Bronsted acid-type biosurfactant for heterocyclization: a green protocol for benzopyran synthesis

Abstract

A natural biosurfactant, a biobased green acidic catalyst for cyclocondensation of salicylaldehyde (or 2-hydroxy naphthaldehyde) and cyclic 1,3-diketones for benzopyran synthesis in water has been reported for the first time. The structures of the final compounds were confirmed with the aid of IR, ¹H NMR, and ¹³C NMR spectroscopy. Lemon extract as a natural biosurfactant provides a micellar media for effective organic transformation. The CMC of lemon extract was determined by the conductivity method. In comparison to the conventional methods, this synthetic pathway complies with several key requirements of green chemistry principles such as the utilization of renewable feedstock, auxiliary aqueous conditions, waste prevention, and atom economy along with the use of biodegradable catalyst. Thus, the reported protocol offers an attractive option because of its ecological safety, environmental acceptance, sustainability, and low-cost straightforward work-up procedure.