Plant-Based Bronsted Acidic Polyphenol Catalyzed Synthesis of 3'-Phenyl-1'H-Spiro[Cyclohexane-1,2'-Quinazolin]-4'(3'H)-Ones and 3'-Phenyl-1'H-Spiro[Cyclopentane-1,2'-Quinazolin]-4'(3'H)-One Derivatives

Abstract

An efficient, metal-free method for the synthesis of 3'-phenyl-1'H-spiro[cyclohexane-1,2'-quinazolin]-4'(3'H)-ones, 4-(tert-butyl)-3'-phenyl-1'H-spiro[cyclohexane-1,2'-quinazolin]-4'(3'H)-ones and 3'-phenyl-1'H-spiro[cyclopentane-1,2'-quinazolin]-4'(3'H)-one derivatives was developed using isatoic anhydride, cycloalkanone and different anilines through one-pot three-component cyclocondensation by utilizing tannic acid(TA)—a weakly acidic natural polyphenol, as a novel inexpensive greener catalyst. The reaction allows rapid cyclocondensation (10–30 min) at reflux condition with 5 mol% of tannic acid to give diversely functionalized spiroquinazolinones in good to excellent yield. This green protocol is of big interest due to employing simple, nontoxic and inexpensive tannic acid as a catalyst and environmentally benign aqueous ethanol as green solvent without the use of any harmful mineral acid and toxic transition metal catalyst.