Biocatalyst Mediated Synthesis of Tryptanthrins Performed Under Ultrasonication

Abstract

The concomitant exploitation of two of the green chemistry tools viz., sonication and biocatalysis is reported here for the synthesis of natural alkaloid, tryptanthrin (indolo[2, 1-b]quinazoline-6,12-dione). High intensity ultrasound was applied to facilitate the release of enzymes by disruption of cells of baker's yeast (Saccharomyces cerevisae) as a biocatalyst. The coupled system is an excellent instance to enhance the rate of biocatalyzed reaction and proved to be 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 affords highly selective conversion with no byproducts.

Conversion of Isatins to Tryptanthrins, Heterocycles Endowed with a Myriad of Bioactivities

“…Other approaches are less straightforward and will not be detailed here. Isatoic anhydride is the most commonly used partner of 2‐H (reaction (i) in Scheme ); one can also cite 2‐nitrobenzoyl chloride (reaction (ii) for which a reduction step is needed), 2‐azidobenzoyl chloride (intramolecular aza‐Wittig reaction (iii)), anthranilamide (reaction (iv) using POCl 3 ),[31h] anthranilic acid (reaction (v) in the presence of SOCl 2 or PCl 5 ),[11a] and more recently 2‐aminoacetophenone and indole (reactions (vi)[29g] and (vii), both using CuI and oxygen). These ways are in general suitable for synthesis of tryptanthrins with different substituents on each side.…”

Synergistic Effect between Ultrasound Irradiation and Na 2 CO 3 in N ‐Acylation Reaction: Applied for the Synthesis of Novel N ‐Acylcyanamide Derivatives

“…The obtained results in Table indicate that increasing the power of ultrasound led to a higher yield of the product. By increasing the power of ultrasonic, the number of cavitation bubbles and their size increased, both happening led to an increase in the maximum collapse temperature, which could accelerate the reaction …”

Role of Enzymes in Synthesis of Biologically Important Organic Scaffolds

“…Alan et al [44] stated the conversion of 2-oxobutanoic acid (1) with the use of L and D form of lactase dehydrogenase to stereospecific isomers of type α-hydroxybutanoic acid (2) and (3) (Scheme-I). L-Lactate dehydrogenase in comparison with D-lactate dehydrogenase has narrower substrate specificity.…”

“…Biocatalysis can be defined as use of whole cells or enzymes in organic synthesis [1][2][3]. This use of enzymes in synthesis of organic compounds has led to the development of Green Chemistry.…”