K. Ravinder

Zeolite Catalyzed Synthesis of bis (Indolyl) Methanes

Abstract HY-Zeolite is found to be a versatile catalyst for the electrophilic substitution reaction of indoles with carbonyl compounds to afford the corresponding bis(indolyl) methanes in good yields. #IICT Communication No. 011208.

Bismuth triflate catalyzed conjugate addition of indoles to α,β-enones

Reaction of indoles with electron deficient olefins under the influence of bismuth triflate has been studied at ambient temperature and affords the corresponding 3-alkylated indoles in excellent yields.

Amberlyst-15-Catalyzed Efficient Synthesis of 1,1-Diacetates from Aldehydes

Abstract Amberlyst-15 was found to be an efficient catalyst for acylation reaction of aldehydes with acetic anhydride at room temperature in dichloromethane. #IICT Communication No. 01/09/04.

Simple and Selective Removal of the t‐Butyloxycarbonyl (Boc) Protecting Group on Indoles, Pyrroles, Indazoles, and Carbolines

Abstract A highly selective and efficient deprotection of the N‐t‐butoxy carbonyl (N‐Boc) group on indoles, pyrroles, indazoles, and carbolines has been achieved in high yields using a catalytic amount of NaOMe as a base in dry MeOH, at ambient temperature. IICT Communication No. 060512.

CAN Catalyzed One‐Pot Synthesis of α‐Amino Phosphonates from Carbonyl Compounds

Abstract α‐Amino phosphonates are synthesized by three component condensation of aldehydes, amines, and diethyl phosphite using ceric ammonium nitrate at room temperature to afford the corresponding α‐amino phosphonates in high yields. #IICT Communication No. 020214. ‡Dedicated to Professor Goverdhan Mehta on his 60th Birthday.

SYNTHESIS OF DIHYDROPYRIMIDINONES: AN IMPROVED CONDITIONS FOR THE BIGINELLI REACTION

A mild and selective method for the synthesis of dihydropyrimidinones using CBr4 in methanol in the Biginelli three component cyclocondensation reactions has been developed. Yields are significantly higher than utilizing classical Biginelli reaction conditions. In the past decades broad ranges of biological activities have been ascribed to partly reduced pyrimidine derivatives. Among these 4-aryl-dihydropyrimidinone derivatives are pharmacologically very important as calcium channel blockers, anti hypertensive agents, and aia-adrenergic antagonists and neuropeptide Υ (NPY) antagonists. In addition dihydropyrimidinone-5-carboxylate core unit is found in many marine natural products including batzelladine alkaloids, which are found to be potentHIV gp-120-CD4 inhibitors. Biginelli reported the first synthesis of various 4-aryldihydropyrimidinone derivatives more than a century ago by a simple one-pot condensation reaction of ß-dicarbonyl compounds with aldehydes and urea or thiourea in the presence of catalytic amount of acid. However, this one-step protocol often suffers from low to moderate yields (20-50 %) of the desired target molecules, particularly in case of substituted aromatic aldehydes or thiourea is employed \ This has lead to the recent disclosure of several improved reaction protocols for the synthesis of dihydropirimidinones such as BF3-OEt2 in combination with transition metal salts with a proper proton source, polyphosphateester, acidic clay montmorillonite KSF, Yb(OTf)3, InCl3, FeCl3, LiC104 and microwave assisted the Biginelli three component cyclo condensation reaction. However, many of these one-pot procedures are generally required strong protic or Lewis acids, prolonged reaction times and high temperature. Thus, the present study explore the use of CBr4 in methanol is an alternative method for one-pot Biginelli reaction for the synthesis of dihydropyrimidinones. * Corresponding author. Tel: 091-40 -7193167; Fax: 091-40 -7160512. E-mail: luchem@iict.ap.nic.in; luchem@yahoo.com.

Chemical transformation of ∆9(15)-africanene and their antibacterial activity

Abstract∆9(15) Africanene, a medicinally important natural sesquiterpenoid has been subjected to chemical transformations to prepare aromatic, hetero aromatic, and aliphatic esters. The synthesized compounds were characterized using IR, mass, and NMR spectrometric analysis. The compounds were evaluated for their antibacterial activities.Graphical Abstract