K.K. Balasubramanian

Vilsmeier-haack reactoin of glycals-a short route to C-2-formyl glycals

A short and straightforward route has been accomplished for the synthesis of C-2-formyl glycals by a Vilsmeier-Haack reaction of glycals.

A novel tandem ferrier rearrangement-cyclisation. Synthesis of chiral pyrano[2,3-b][1]benzophyran system.

A novel synthesis of chiral pyrano[2,3-b][1] benzopyrans by reaction of 2-C-acetoxymethylglycals 1 and 2 with phenols under Lewis acid catalysis in reported.

Claisen rearrangement of aryl propargyl ethers in poly(ethylene glycol)- a remarkable substituent and solvent effect☆

The Claisen rearrangement of aryl propargyl ethers in poly(ethylene glycol) - 200 at 200°C affords products in good yields. Aryl propargyl ethers containing electron donating groups yield (2H)-benzopyrans and those containing electron withdrawing groups yield 2-methylbenzofurans.

Microwave Induced Ferrier Rearrangement

Abstract A short and facile entry to the 2, 3-unsaturated O-arylglyco sides via microwave induced Ferrier rearrangement of acetylated glucal is reported.

A photochemical route to 2-alkenyl- and 2-ethynylbenzofurans

Intramolecular cyclisation of 1,5-biradicals generated by irradiation of o-alkenyloxy and o-alkynyloxybenzophenones led to a facile synthesis of 2-alkenyl-3-phenyl and 2-ethynyl-3-phenylbenzofurans.

Reaction of 2,3-unsaturated aryl glycosides with Lewis acids : a convenient entry to C-aryl glycosides

Abstract A facile synthesis of 2′,3′-unsaturated-C-aryl glycosides by BF 3 .Et 2 O mediated ‘O’ to ‘C’ transformation of 2,3-unsaturated aryl glycosides is reported.

A facile synthesis of 3-alkylchromanones and chromones

Abstract A simple and high yielding route to 3-alkylchromanones and 3-alkylchromones has been achieved from 3-alkyl-3-phenyl-sulphonyl-4-chromanones. A simple and high yielding route to 3-alkylchromanones and 3-alkylchromones has been achieved from 3-alkyl, 3-phenylsulphonyl-4-chromanones.

Thermal behaviour of aryl γ-haloprcpargyl ethers

Abstract A systematic study of the behaviour of aryl γ-halopropargyl ethers under thermal condition was undertaken. Aryl γ-bromopropargyl ethers 2 underwent unique transformation in N,N-diethylanillne (215°C, 6 h) giving rise to a mixture of products 3 , 4 and 5 , whereas, under similar conditions aryl γ-chloropropargyl ethers ulbar|8, afforded 4-chlorochromenes, 9. A remarkable substituent and solvent effect has been observed in the thermolysis of these aryl γ-bromo and γ-chloropropargyl ethers, rendering this transformation as a method for the synthesis of a number of substit uted 4-bromochromenes 3 , 4-chlorochromenes 9 and chroman-4-ones 7 . In contrast, solution thermolysis of aryl γ-iodopropargyl ether 11 afforded aryl propargyl ether 1 as the major product.

A novel synthesis of spirochromenes

The Mitsunobu coupling of cyclic tertiary ethynyl carbinols followed by the Claisen rearrangement of the ethers obtained provides a short, novel entry to spirochromene systems.

A simple route for the synthesis of 4-chlorochromenes and chroman-4-ones

A one pot synthesis of a number of 4-chlorochromenes and chroman-4-ones was achieved from γ-chloropropargyl aryl ethers proceeding through Claisen rearrangement, depending upon the solvent of choice.