Subhas Chandra Roy

An efficient chemo and regioselective oxidative nuclear bromination of activated aromatic compounds using lithium bromide and ceric ammonium nitrate

Abstract A mild, efficient and highly chemo- and regioselective method for the bromination of electron rich aromatic molecules has been developed by electrophilic substitution of Br + , which was generated in situ from LiBr using ceric ammonium nitrate as the oxidant. Free aromatic amines remained unaffected under the reaction conditions.

A mild and efficient method for the selective cleavage of tert-butyldimethylsilyl ethers to alcohols

Abstract A mild and efficient method for the selective deprotection of primary allylic and homoallylic, primary benzylic and aryl tert-butyldimethylsilyl (TBDMS) ethers has been established using a combination of H 2 O and DMSO at 90°C. All other primary and secondary TBDMS ethers remained unaffected under the reaction condition. The method is very effective in deprotection of TBDMS ethers in the presence of other sensitive functional groups.

Regio and stereoselective formation of dihydrofurans by ceric ammonium nitrate mediated oxidative [3+2] cycloaddition of 1,3-diketones to cinnamic esters

Abstract Regio and stereoselective syntheses of dihydrofurans were accomplished by ceric ammonium nitrate mediated oxidative [3+2] cycloaddition of 1,3-diketones to cinnamic esters in high yield.

Stereoselective total synthesis of (±)-Paulownin and (±)-Isogmelinol through radical annulation route

Abstract A highly stereocontrolled synthesis of furofuran lignans, (±)-Paulownin (1a) and (±)-Isogmelinol (1b) is described involving intramolecular radical cyclisation as a key step.

SYNTHESIS OF FUSED ACETALS BY CERIC AMMONIUM NITRATE MEDIATED CYCLOADDITION OF 1,3-DICARBONYL COMPOUNDS TO CYCLIC ENOL ETHERS

Abstract Treatment of β-diketones and β-ketoesters with ceric ammonium nitrate and sodium hydrogen carbonate in acetonitrile leads to the formation of intermediates which add efficiently to cyclic enol ethers to furnish fused acetals in good yields.

Stereoselective synthesis of trisubstituted tetrahydrofurans by radical cyclisation reaction using a hypophosphite salt. Application to the total synthesis of (±)-dihydrosesamin

The stereoselective synthesis of tetrahydrofurans has been achieved from bromoalkynes and bromoalkenes by intramolecular radical cyclisation using a hypophosphite salt. This radical cyclisation strategy has successfully been applied to the total synthesis of a naturally occurring bioactive furanolignan, dihydrosesamin.

A mild and efficient method for oxidative halodecarboxylation of α,β-unsaturated aromatic acids using lithium bromide/chloride and ceric ammonium nitrate

Abstract A mild and efficient ecofriendly method for the halodecarboxylation of α,β-unsaturated aromatic acids has been developed by using lithium bromide/chloride and ceric ammonium nitrate in acetonitrile–water at room temperature to afford the vinyl halides in moderate to good yields.

Titanocene(III) Chloride Mediated Radical-Induced Addition to Baylis−Hillman Adducts: Synthesis of (E)- and (Z)-Trisubstituted Alkenes and α-Methylene/Arylidene δ-Lactones

Baylis-Hillman adduct underwent smooth radical-induced condensation with activated bromo compounds and epoxides using titanocene(III) chloride (Cp2TiCl) as the radical generator. The reactions of activated bromo compounds with 3-acetoxy-2-methylene alkanoates provided (E)-alkenes exclusively, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles led to (Z)-alkenes as the major product. The reactions of epoxides with Baylis-Hillman adduct furnished alpha-methylene/arylidene-delta-lactones in good yield via addition followed by in situ lactonization.

Total synthesis of (±)-Dihydroprotolichesterinic acid and Formal synthesis of (±)-Roccellaric acid by radical cyclisation of an epoxide. Using a transition-metal radical source

Abstract A short and efficient total synthesis of (±)-Dihydroprotolichesterinic acid (1) and Formal synthesis of (±)-Roccellaric acid (2) has been acheived by radical cyclisation of epoxide using a transition metal radical source.

Stereoselective radical annulation route to the synthesis of (±)-paulownin and (±)-isogmelinol

Abstract A highly stereocontrolled synthesis of (±)-paulownin (1a) and (±)-isogmelinol (1b) is reported involving intramolecular radical cyclisation reaction as a key step.