01684nas a2200241   4500008004100000022001400041245013600055210006900191260007700260300001400337490000700351520076700358653001201125653001201137653001401149653002801163653002101191100002201212700002501234700002301259700002901282856013101311       2013                        eng d  a2192-650600aHighly efficient povidone-phosphotungstic acid catalyst for the tandem acetalization of aldehydes to bis- and tris(indolyl)methanes0 aHighly efficient povidonephosphotungstic acid catalyst for the t  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcNOV  a1393-13990 v783 a<p>A novel, nonleachable hybrid of heteropoly acid and polyvinylpyrrolidone (or povidone) catalyzes the acetalization of aldehydes in methanol at room temperature followed by reaction with indole to give bis(indolyl)methanes (BIMs) and tris(indolyl)methanes (TIMs) in quantitative yields (90-97%). The catalyst was shown by pyridine FTIR spectroscopy to possess BrOnsted acidity, and the hybrid formation was confirmed by XRD and (PNMR)-P-31 studies. Friedel-Crafts alkylation of indole as well as the tandem synthesis of BIMs and TIMs were established with several types of carbonyl and indole substrates to give the corresponding products quantitatively. The catalyst was recycled efficiently for three successive runs without losing its original activity.</p>10aacetals10aAcidity10aaldehydes10aheterogeneous catalysis10aheteropoly acids1 aKamble, Sumit, B.1 aSwami, Rameshwar, K.1 aSakate, Sachin, S.1 aRode, Chandrashekhar, V.  uhttp://library.ncl.res.in/content/highly-efficient-povidone-phosphotungstic-acid-catalyst-tandem-acetalization-aldehydes-bis-001706nas a2200169   4500008004100000022001400041245016900055210006900224260011000293300001400403490000600417520091300423100002201336700002201358700002901380856012701409       2015                        eng d  a2044-475300aHighly efficient triphenyl(3-sulfopropyl)phosphonium functionalized phosphotungstic acid on silica as a solid acid catalyst for selective mono-allylation of acetals0 aHighly efficient triphenyl3sulfopropylphosphonium functionalized  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY  a4039-40470 v53 a<p>Silica supported phosphotungstic acid functionalized with triphenyl(3-sulfopropyl)phosphonium (PW-Si/TPSP) was developed as a solid acid catalyst for C-C bond formation via Hosomi-Sakurai allylation of acetals. Functionalization of PW as well as its binding to silica was confirmed by solid state P-31-NMR and Si-29-NMR, respectively. Among the various catalysts prepared, the 30% PW loaded (30PW-Si/TPSP) catalyst gave an excellent yield of homoallyl ethers (HAEs) via selective mono-allylation of acetals with allyltrimethylsilane. A plausible reaction pathway has also been proposed in which the strong Bronsted acid sites of 30PW-Si/TPSP play an important role in activating the acetals to form the corresponding oxonium cations. The versatility of our catalyst was demonstrated for the allylation of a wide variety of acetals while its stability was established in five successful recycling runs.</p>1 aKamble, Sumit, B.1 aShinde, Suhas, H.1 aRode, Chandrashekhar, V.  uhttp://library.ncl.res.in/content/highly-efficient-triphenyl3-sulfopropylphosphonium-functionalized-phosphotungstic-acid-0