Dearomatizing Naphthol Mannich Bases toward Spiro Thiazolidinethiones Catalyzed by Recyclable Reduced Graphene Oxide with Air as Oxidant

Abstract

Reduced graphene oxide (rGO) served as a green catalyst with ambient oxygen as a clean oxidant for dearomatizing cyclizations of naphthol Mannich bases with carbon disulfide under mild conditions. Notably, this process provides novel and efficient one-pot access to spiro thiazolidinethione compounds. Fourier transform infrared analysis, transmission electron microscopy, atomic force microscopy, X-ray photoelectron microscopy, thermogravimetric analysis, Raman analysis, and X-ray diffraction were used to characterize rGO. And, the rGO can be reused at least six times without significant loss of catalytic activity. A possible reaction mechanism was proposed. In addition, some target compounds showed inhibition against Sclerotinia sclerotiorum, Botrytis cinerea, Thanatephorus cucumeris, and other fungi.

Contemporary progress in the green synthesis of spiro-thiazolidines and their medicinal significance: a review

“…N. Ma et al 73 developed a new and effective one-pot access to spiro-thiazolidinethione derivatives ( 35 or 35′ ) readily from naphthol Mannich bases and CS 2 promoted by rGO, an eco-friendly and reusable carbocatalyst under mild conditions (Scheme 10). Under moderate circumstances, reduced graphene oxide (rGO) worked as a green catalyst for dearomatizing cyclization of naphthol Mannich bases ( 33 or 33′ ) with carbon disulfide ( 34 ) with ambient oxygen as a clean oxidant.…”

Gold‐Catalyzed Dearomatization of 2‐Naphthols with Alkynes

“…In the realm of catalytic dearomatization reactions, naphthol derivatives are facing growing attention, resulting in the preparation of densely functionalized and stereochemically defined naphthalen‐2(1 H )‐one, which is a molecular motif featured in numerous naturally occurring and bioactive compounds (Figure ). The catalytic dearomatization of 2‐naphthols found elegant applications with the use of strongly activated electrophiles through the realization of new C−X (X: oxidative approach, for example, hydroxylation, amination,, thiolation, and halogenation) as well as C−C bonds at the C(1) position . In the latter case, the use of strongly activated carbon‐based electrophiles is commonly required to access mild reaction conditions and synthetically useful selectivity.…”

Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst

“…[2] Recently,t he immobilization of organocatalysts on solids upports throughr obustc ovalent bonds hasb ecomeavery attractive solutionw ith minimum production waste and maximum catalytic efficiency.I ta lso exhibits many other merits, such as easy separation and recovery from the reactions ystem, excellent recycling potential, good stability,a nd straightforwardo peration, etc. [3] Currently,b oth established and emerging solid supports, such as silicas, [4] polymers, [5] zeolites, [6] metal nanoparticles, [7] graphenes, [8] and metal-organic frameworks (MOFs), [9] etc. have been appliedt om eet the demands of sustainable development and green chemistry.A lthough fruitful advances have been discovered on the basis of functionalized materials based on different supports, there are still many obstacles to restrict its commercial process.…”

“…It also exhibits many other merits, such as easy separation and recovery from the reaction system, excellent recycling potential, good stability, and straightforward operation, etc . Currently, both established and emerging solid supports, such as silicas, polymers, zeolites, metal nanoparticles, graphenes, and metal–organic frameworks (MOFs), etc. have been applied to meet the demands of sustainable development and green chemistry.…”