Basi V. Subba Reddy

Three-component coupling reactions in ionic liquids: a facile synthesis of α-aminonitriles

Aryl imines, derived in situ from aldehydes and amines, smoothly undergo addition with trimethylsilyl cyanide in 1-butyl-3-methylimidazolium tetrafluoroborate or 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquids under mild and neutral reaction conditions to afford the corresponding α-aminonitriles in excellent yields. The ionic liquids can be recycled in five to six runs without any apparent loss of activity.

Gold(III) chloride-catalyzed three-component reaction: a facile synthesis of alkynyl derivatives of 1,2-dihydroquinolines and isoquinolines.

Gold(III) chloride is found to be an effective catalyst for the addition of alkynes on activated quinoline/isoquinolines to produce a series of alkynyl-substituted 1,2-dihydroquinolines and isoquinolines in a single-step operation. The easy availability of starting materials, convenient synthetic procedure, operational simplicity, and high regioselectivity makes this strategy very useful for the preparation of enyne derivatives of aza-aromatic compounds.

UNPRECEDENTED SYNTHESIS OF HANTZSCH 1,4-DIHYDROPYRIDINES UNDER BIGINELLI REACTION CONDITIONS*

Hantzsch 1,4-dihydropyridines are synthesized in high yields by a one-pot cyclocondensation of aldehyde, β-ketoester, and urea on the surface of silica gel under microwave irradiation in solvent-free conditions.

Versatile intramolecular aza-Prins and Prins cyclization of aryl epoxides: a facile synthesis of diaza-, oxa-aza-, and dioxa-bicycles.

Aryl epoxides undergo coupling smoothly with (E)-hex-3-ene-1,6-ditosylamide in the presence of 10 mol % p-TSA in 1,2-dichloroethane at 75 degrees C to produce the corresponding 1,5-ditosyl-octahydro-1H-pyrrolidino[3,2-c]pyridines in good yields with high trans-selectivity, whereas the coupling of (Z)-hex-3-ene-1,6-ditosylamide gave cis-fused octahydro-1H-pyrrolidino[3,2-c]pyridines predominantly. The use of readily available p-TSA makes this method simple, convenient, and practical.

Ultrasound-accelerated synthesis of 3,4-dihydropyrimidin-2(1H)-ones with ceric ammonium nitrate

Ceric ammonium nitrate efficiently catalyzes the three component condensation of an aldehyde, β-ketoester and urea in methanol to afford the corresponding dihydropyrimidinones in excellent yields under sonication. Other oxidants such as manganese triacetate and Oxone were also found to catalyze this transformation under similar conditions.

Montmorillonite clay-catalyzed stereoselective syntheses of aryl-substituted (E)- and (Z)-allyl iodides and bromides

An efficient and rapid procedure for the synthesis of allyl iodides and bromides from Baylis–Hillman adducts using clay-supported sodium iodide and sodium bromide is described. Improved yields and enhanced rates have been achieved by employing microwave irradiation.

A mild and selective cleavage of trityl ethers by CBr4-MeOH.

Trityl ethers are selectively deprotected to the corresponding alcohols in high yields by CBr4 in refluxing methanol under neutral reaction conditions. Other hydroxyl protecting groups like isopropylidene, allyl, benzyl, acetyl, benzoyl, methyl, tosyl, prenyl, propargyl, tert-butyldiphenylsilyl and p-methoxybenzyl ethers are unaffected.

A mild and selective cleavage of tert-butyldimethylsilyl ethers by indium(III) chloride

Alkyl tert-butyldimethylsilyl ethers are selectively deprotected to the corresponding alcohols in high yields for the first time by indium(III) chloride in refluxing aqueous acetonitrile. Several functional groups like OBn, Boc, CBz, OBz, O-allyl, OTBDPS, OAc, OMe, ethers, esters and olefins present in the substrate are unaffected.

LiBF4-mediated C-glycosylation of glycals with allyltrimethylsilane: a facile synthesis of allyl C-glycosylic compounds.

The treatment of glycals with allyltrimethylsilane in the presence of lithium tetrafluoroborate in acetonitrile gave the corresponding allyl 2,3-unsaturated C-glycosylic compounds in excellent yields with high anomeric selectivity.

InCl3 immobilized in ionic liquids: a novel and recyclable catalytic system for tetrahydropyranylation and furanylation of alcohols

A mild and highly efficient method has been developed for the protection of hydroxyl compounds as tetrahydropyranyl and furanyl ethers using a catalytic amount of indium trichloride immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid under mild conditions. A wide range of functional and protecting groups such as THP, TBDMS, TBDPS, PMB, MOM ethers, acetonides, olefins and epoxides are compatible with ionic liquids. Monoprotection of diols has also been achieved using this novel procedure.