Biocatalyst mediated synthesis of tryptanthrins performed under ultrasonication

Abstract

The concomitant exploitation of two of the green chemistry tools <em>viz</em>., sonication and biocatalysis is reported here for the synthesis of natural alkaloid, tryptanthrin (indolo[2,1-<em>b</em>]quinazoline-6,12-dione). High intensity ultrasound has been applied to facilitate the release of enzymes by disruption of cells of baker&rsquo;s yeast (<em>Saccharomyces cerevisae</em>) as a biocatalyst. The coupled system is an excellent instance of enhanced rate of biocatalyzed reaction and has proven to be a green alternative to existing methodologies for the synthesis of tryptanthrins. The present method is bestowed with merits such as mild and clean reaction conditions, operational simplicity, tolerance for a wide variety of substituents, green aspects through the avoidance of toxic metal catalysts and highly selective conversion with no byproducts.