Bhaskar Dhotare

Facile approach towards the synthesis of homochiral functionalised alcohols from 4-O-[(tert)-butyldimethylsilyl]-2,3-O-cyclohexylidene-l-threose of (l)-(+)-tartaric acid origin

Abstract ( l )-(+)-Diethyl tartarate 2 has been transformed into the aldehyde 6 . Grignard additions to 6 take place with moderate diastereoselectivity giving predominant formation of the anti products 8a – e . However, in each case the diastereoalcohols are easily separable by column chromatography giving rise to the formation of a series of functionalised homochiral alcohols 7 and 8 . On the other hand Zn mediated allylation and propargylation of 6 in the presence of water proceeded efficiently with almost absolute (>99%) stereoselective formation of versatile functionalised homoallylic 8d and homopropargylic 8e alcohols respectively.

SbCl3-catalyzed solvent-free Friedel–Crafts reaction of phenols with mandelic acids to 3-aryl benzofuran-2(3H)-ones: Synthesis of spirocyclic 2,3-dihydrobenzofuran-2-ones

ABSTRACT A facile, SbCl3-catalyzed, one-pot, tandem Friedel–Crafts/lactonization reaction of phenols and mandelic acids has been developed under solvent-free conditions to afford 3-aryl benzofuran-2(3H)-ones in good to high yields (52–90%). Additionally, the utility of 3-aryl benzofuran-2(3H)-ones is demonstrated by using them as precursors in the synthesis of a new class of spirocyclic benzofuran-2-ones using classical synthetic methodologies. GRAPHICAL ABSTRACT

Catalytic Oxidation of 3-Arylbenzofuran-2(3H)-ones with PCC-H5IO6: Syntheses of 3-Aryl-3-hydroxy/3-amido-3-arylbenzofuran-2(3H)-ones

A pyridinium chlorochromate (PCC)-mediated facile oxidative dimerization of 3-arylbenzofuran-2-ones at ambient temperature was developed which undergo oxidative cleavage to 3-aryl-3-hydroxy-benzofuran-2-ones with PCC at elevated temperatures. Finally, direct oxidation of 3-arylbenzofuran-2-ones to 3-aryl-3-hydroxy-benzofuran-2-ones was realized using a combination of PCC (10 mol %) and 2.0 equiv of H5IO6. The synthesized 3-aryl-3-hydroxy-benzofuranones were further converted to corresponding 3-amido-3-aryl-benzofuranones in high yields by Ritter reaction. Thus, the present protocol provides a nonconventional approach to C-3 hydroxylation of 3-arylbenzofuranones via their dimer using a catalytic amount of inexpensive chromium(VI) oxidant.