Zinc Hydrogensulfate as an Efficient Catalyst for Preparation of β-Amido Carbonyl Compounds

A one‐pot and efficient three‐component condensation of benzaldehyde derivatives, enolizable ketones or ketoesters, acetyl chloride, and acetonitrile or benzonitrile under ambient conditions in the presence of zinc hydrogensulfate for the synthesis of β‐amido carbonyl compounds is described. The simple experimental procedure, high to excellent yields of products and preparation of diastereoselective β‐acetamido ketoesters are strong features of the presented method.     

Uncatalyzed,One-pot Synthesis of 3,3'-(Benzylene)bis(4-hydroxy-2H-chromen-2-one)Derivatives under Thermal Solvent-free Conditions

A series of 3,3′‐(benzylene)bis(4‐hydroxy‐2H‐chromen‐2‐one) derivatives have been synthesized from condensation reactions of 4‐hydroxycoumarin with benzaldehydes under thermal solvent‐free conditions. This environmentally friendly synthesis is uncatalyzed and affords the desired products in excellent yields.     

Preparation of Silyl Ethers Using Hexamethyldisilazane in the Presence of N‐Bromosuccinimide under Mild and Solvent‐Free Conditions

A mild, simple, novel and highly efficient method for the rapid protection of various primary, secondary, tertiary aliphatic and aromatic alcohols using hexamethyldisilazane (HMDS) in the presence of N-bromosuccinimide (NBS) as an active, inexpensive, non-toxic and readily available catalyst under solvent-free conditions is described. Trimethylsilyl ethers were prepared in high to excellent yields with short reaction time under mild and almost neutral reaction conditions.     

PPA-SiO_2 as a Heterogeneous Catalyst for Efficient Synthesis of 2-Substituted-1,2,3,4-tetrahydro-4-quinazolinones under Solvent-free Conditions

Silica‐supported polyphosphoric acid (PPA‐SiO₂) catalyzed efficiently the reaction of anthranilamide with aryl aldehydes or ketones under solvent‐free conditions to afford the corresponding 1,2,3,4‐tetrahydro‐4‐quinazolinone derivatives. This work consistently has the advantages of excellent yields, short reaction time, simple experimental and work‐up procedures. The heterogeneous catalyst could be recovered and recycled for several times without any loss of its activity.     

Sodium Hydrogen Sulfate as Effective and Reusable Heterogeneous Catalyst for the One-pot Preparation of 14H-[(Un)substituted phenyl]-dibenzo[a,j]xanthene Leuco-dye Derivatives

NaHSO₄•H₂O has been used as an efficient catalyst for the one-pot preparation of 14H-[(un)substituted phenyl]-dibenzo[a,j]xanthene leuco-dye derivatives by condensation of β-naphthol with substituted benzaldehydes under microwave and thermal conditions. This method has the advantages of high yields, a green reaction, an efficient and cost-effective method, simple procedures, short reaction time, and easy workup.     

Preparation and Application of Perchloric Acid Supported on Alumina (Al2O3-HClO4) to the Synthesis of α-(α-Amidobenzyl)-β-naphthols

Preparation of perchloric acid supported on alumina and its primary application as a solid supported heterogeneous catalyst to the synthesis of α-(α-amidobenzyl)-β-naphthols by a one-pot, three-component condensation of benzaldehydes, β-naphthol and acetamide or benzamide under thermal solvent-free conditions were described. The present methodology offers several advantages such as simple procedure, shorter reaction time, and excellent yields.     

N-Bromosuccinimide Catalyzed One-pot and Rapid Synthesis of Acetamidobenzyl Naphthols under Mild and Solvent-free Conditions

An efficient, facile and expeditious direct protocol for the preparation of acetamidobenzyl naphthols employing a multi-component and one-pot condensation reaction of 2-naphthol, benzaldehydes, and acetamide in the presence of N-bromosuccinimide (NBS) under thermal and microwave irradiation conditions has been described. The present protocol with NBS catalyst is convincingly superior to the recently reported catalytic methods.     

PPA-SiO2 Catalyzed Multi-component Synthesis of N-[α-(β-Hydroxy-α-naphthyl)(benzyl)] O-Alkyl Carbamate Derivatives

Silica-supported polyphosphoric acid (PPA-SiO2) was found to be an efficient catalyst for the multi-component condensation reaction of benzaldehydes, 2-naphthol, and methyl/benzyl carbamate to afford the corresponding N-[α-(β-hydroxy-α-naphthyl)(benzyl)] O-alkyl carbamate derivatives in good to excellent yields. This new approach consistently has the advantage of short reaction time, high conversions, clean reaction profiles, and simple experimental and work-up procedures.