M. Satish Kumar

Ultrasonic and Microwave-Assisted Synthesis of β-Nitro Styrenes and Nitro Phenols with Tertiary Butyl Nitrite under Acid-Free Conditions

Abstract Tertiary butyl nitrite (TBN) is an acid-free and safe nitrating agent that provides preferentially β-nitrostyrenes with cinnamic acids and corresponding nitro derivatives with phenols in good yields under classical conditions. However, ultrasonic and microwave-assisted reactions reduced the reaction times substantially and enhanced the yields from good to excellent. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Oxalylchloride/DMF as an Efficient Reagent for Nitration of Aromatic Compounds and Nitro Decarboxylation of Cinnamic Acids in Presence of KNO3 or NaNO2 Under Conventional and Nonconventional Conditions

Nitration of aromatic compounds and cinnamic acids with oxalylchloride/DMF afforded the corresponding nitro derivatives in the presence of KNO3 or NaNO2 under conventional and nonconventional (ultrasonic and microwave) conditions. The present methodology offers several benefits such as excellent yields, simple work-up procedure, and short reaction times. The yields obtained under present methodology are comparable with those obtained from (POCl3/DMF/KNO3 or NaNO2) and (SOCl2/DMF/KNO3 or NaNO2) systems followed by shorter reaction times. The reaction times of sonication and microwave conditions are very shorter than those of the conventional conditions.

Zeolite H-Sdusy Powder (Cbv720) as a Recyclable Catalyst for an Efficient Thiocyanation of Aromatic and Heteroaromatic Compounds in Acetonitrile

GRAPHICAL ABSTRACT Abstract Thiocyanation of various aromatic and heteroaromatic compounds has been studied using Zeolite H-SDUSY Powder (CBV720) as catalyst and ammonium thiocyanate (NH4SCN) as thiocyanation reagent in acetonitrile medium. Reactions afforded good yields of products under stirred conditions at reflux temperature. Reactions underwent enhancements under sonication (using an ultrasonic probe of 24 kHz frequency) and microwave irradiation. The use of ultrasound decreased the reaction times from (7-12 h) to few minutes (70-150 min). The use of microwave irradiation much more effectively enhanced the reaction rates than sonicated and conventional protocols used in this study.

Ultrasonic and microwave effects in polyethylene glycol-bound metal nitrate initiated nitration of aromatic compounds under acid free conditions

ABSTRACT Ultrasonic and microwave-assisted practical methods have been developed for the nitration of phenols using metal nitrates in aqueous polyethylene glycol (PEG) media. Solvent is recycled three times for reproducibility. It was recycled with minimum loss and decomposition. Developed protocols were cost effective, simple and efficient, which afforded nitration products in good to excellent yields. The observed hyperchromic/hypochromic shifts in the UV/VIS spectra of metal nitrates in PEG solutions could be due to the plausible in situ formation of “PEG-bound M(II) nitrate” and thereby the release of nitronium ion () during the course of reaction when metal nitrate [M(II)nitrate] is added to PEG. Nitronium thus formed most likely is captured by aromatic compound to afforded nitro aromatics.

Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions

ABSTRACT Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions. GRAPHICAL ABSTRACT

Ultrasonically Assisted Decarboxylative Bromination of α,β-Unsaturated Carboxylic Acids Under Vilsmeier-Haack Conditions

An efficient method for decarboxylative bromination of cinnamic acids (α,β-unsaturated carboxylic acids or 3-arylpropenoic acids) was achieved under relatively mild conditions using Vilsmeier-Haack reagent and KBr in acetonitrile media. Vilsmeier-Haack reagent is prepared by using 1:1 ratio of oxychloride (SOCl2 or POCl3) and DMF under chilled condition. Ultrasonically assisted reactions underwent smoothly with highly significant rate enhancements and afforded bromostyrenes as products in very good yields even though the reactions were too sluggish.

Cesium carbonate as efficient catalyst for chemoselective transesterification of β-ketoesters under conventional and unconventional conditions

Transesterification of β-ketoesters with different alcohols has been studied under conventional and unconventional conditions using the simple desktop chemical cesium carbonate as catalyst. These methods enabled transesterification of β-ketoesters in good yields with dramatic rate acceleration and reduced reaction times. The procedures which used unconventional methods, for example sonication and microwave irradiation, are highly promising compared with conventional procedures.Graphical AbstractScheme 1 General Equation for a transesterification reactionScheme 2 Transesterification of β-ketoesters

Prussian Blue as an Efficient Catalyst for Rate Accelerations in the Transesterification of β-Ketoesters

Prussian blue triggered transesterification of ethylacetoacetate with various alcohols underwent efficiently. The reaction is mild, eco-friendly, and selective with good yields. The proposed reaction pathway depicts the formation of an intermediate by the interaction of β-ketoesters with catalytic site of the Prussian blue, followed by nucleophilic attack of the alcohol at the electrophilic center followed by successive elimination of the proton to give the product. Observed longer reaction times under conventional conditions reduced amazingly under sonication and microwave irradiation followed enhanced yield of products.