Balaram Patro

Radical-polar crossover reactions with polymer-supported tetrathiafulvalene

Abstract Polymer-supported tetrathiafulvalene reagents have been prepared and their reactivity in redical-polar crossover reactions compared to tetrathiafulvalene itself. The reagents give easy separation of products. A regeneration step permits re-use of the polymer-supported reagent.

(1-1)-Linked C-Disaccharides – Synthesis of Bis(β-D-Galactopyranosyl)Methane

ABSTRACT Bis[C-(galactal-1-yl)]carbinol derivative 2, which is readily obtained by transformation of galactal into a vinyl carbanion and then reaction with a C1-electrophile, was transformed into the title compound (1b). The procedure required first temporary protection of the carbinol hydroxy group and subsequent transformation of the galactal moiety into the galactopyranosyl moiety. Then deoxygenation of the carbinol and final deprotection could be carried out.

Tandem carbocationic cyclization of bis(methylthio)methylene arylcyclopropyl ketones : a promising sequence for assembling functionalized cyclopent[a]indene framework

Abstract A novel route for assembling cyclopent-[a]indene framework bearing useful functionalities has been developed through bis(methylthio) carbenium ion mediated Lewis acid induced tandem cyclization of bis-(methylthio) methylene aryl cyclopropyl ketones 1b – d and the corresponding carbinols 11b–d .

A highly stereoselective synthesis of substituted butadienes and conjugated polyenes

A highly stereoselective synthesis of 1,3-butadienes and its higher enyl analogs has been developed through thermal dehydrative ring opening of cyclopropyl carbinols in dimethylsulphoxide.

Facile one pot thermal dehydration and dethioacetalization of β-hydroxydithioacetals with dimethyl sulphoxide: synthesis of α,β-unsaturated aldehydes

Abstract The acyclic and cyclic β -hydroxydithioacetals 3a-m and 4a-b obtained by sodium borohydride reduction (or Grignard addition) of the corresponding β -oxodithioacetals 2a-m are shown to undergo facile one pot thermal dehydration and dethioacetalization in the presence of dimethyl sulphoxide to afford the corresponding ene- and polyene aldehydes 5a-m and 6a-b in good yields. The probable mechanism of dethioacetalization with dimethyl sulphoxide has also been discussed.

Rearrangement studies on 3,3-bis(methylthio)-1-(arylcyclopropyl) -2-propen-1-ols: synthesis of functionalized cyclopentenes and polyene esters

The cyclopropyl carbinols 8 and 9 obtained by either borohydride reduction (or Grignard addition) of the cyclopropyl ketones 1 are shown to undergo acid induced ring opening and intramolecular cyclization (5-exo or 6-endo) or deprotonation to afford either cyclopentene, biphenyl or conjugated polyene derivatives depending on the nature of Lewis acid, reaction conditions and the structuralfeatures present in the cyclopropyl carbinol. A probable mechanism for the formation of various products has been suggested.

SPF32629A and SPF32629B: enantioselective synthesis, determination of absolute configuration, cytotoxicity and antibacterial evaluation.

We report herein an efficient enantioselective synthesis of SPF32629A and SPF32629B through one-pot enantioselective reduction and protecting-group-free regioselective O-acylation strategy. The absolute configuration of the enantiomerically pure isomers was established by Mosher ester analysis. The inhibitory potencies of the synthesized compounds were assayed in vitro against a panel of microorganisms and against A549 human lung adenocarcinoma cell line. Compounds 2, 11 and 12 displayed moderate to potent antibacterial activity against all the tested strains and compounds 7, 8, 2, 11 and 12 exhibited significant cytotoxicity in a dose-dependent manner with an IC50 values ranging from 2.92 to 4.14 μg/ml and 8-11 μM.

Stepwise controlled reduction of α-Oxoketene dithioacetals with Zn/ZnCl2-TMEDA in ethanol

Abstract α-Oxoketene dithioacetals 1 are shown to undergo highly selective conjugate reduction with Zn/ZnCl 2 -TMEDA in refluxing ethanol under controlled reaction conditions to afford β-methylthiomethylene ketones 6 , β-methylthioketones 7 and the completely desulphurized α-methylketones 8 in sequential manner.

Concise Total Synthesis of (−)-Erinapyrone B from D-(+)-Malic Acid

Abstract A convenient and facile enantioselective synthesis of (−)-erinapyrone B from commercially available D-(+)-malic acid has been achieved in seven steps. One of the key steps in this synthesis was the one-pot reaction of palladium(II)-mediated Wacker-type oxidative cyclization in the presence of a catalytic amount of p-toluenesulphonic acid (p-TsOH) which has been found to be effective for the preparation of enantiopure 2,3-dihydro-4H-pyran-4-one from the corresponding enantiopure β-hydroxyenone via enantio-enriched diketohydroxy intermediate. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT