@article { ISI:000237651600007, title = {Palladium mediated cycloisomerization of sugar alkynols: synthesis of cyclic enol-ethers and spiroketals}, journal = {Tetrahedron Letters}, volume = {47}, number = {22}, year = {2006}, month = {MAY}, pages = {3649-3652}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Functionalized bicyclic enol-ethers and spiroketals are prepared by Pd catalyzed cycloisomerization of 3-C-alkynylfuranosyl derivatives. Cycloisomerization of differently substituted alkyne derivatives revealed a preference for 6-endo-dig cyclization over 5-exo-dig if the substituent is not sufficiently electron withdrawing. The scope of these cycloisomerizations has been further extended by integrating with conjugate addition. (c) 2006 Elsevier Ltd. All rights reserved.

}, keywords = {c-alkynylfuranose, cycloisomerization, enol-ether, Palladium, Spiroketal}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2006.03.143}, author = {Ramana, C. V. and Mallik, Rosy and Gonnade, Rajesh G. and Gurjar, Mukund K.} } @article { ISI:000254901800024, title = {Influence of electronic factors on palladium-mediated cycloisomerization: a systematic investigation of competitive 5-exo-dig versus 6-endo-dig cyclizations of sugar alkynols}, journal = {Tetrahedron}, volume = {64}, number = {1}, year = {2008}, month = {JAN}, pages = {219-233}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Pd-mediated cycloisomerization of 3-C-alkynyl-allo- and ribofuranose derivatives was investigated in detail to understand the influence of electronic factors on the regioselectivity in ring closure reaction. The reactions in general are influenced by the electronic nature of the substituent on the alkyne unit. A preference for endo-dig cyclization over exo-dig is noted, if the alkynyl substituent is not sufficiently electron withdrawing, (c) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {C-alkynyl furanose, cycloisomerization, enol ether, Palladium, Spiroketal}, issn = {0040-4020}, doi = {10.1016/j.tet.2007.10.072}, author = {Ramana, C. V. and Mallik, Rosy and Gonnade, Rajesh G.} } @article { ISI:000271713300024, title = {Influence of electronic factors on pd-mediated cycloisomerization: a systematic investigation of competitive 6-exo-dig versus 7-endo-dig cyclizations of sugar alkynols}, journal = {Tetrahedron}, volume = {65}, number = {47}, year = {2009}, month = {NOV}, pages = {9819-9832}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Pd-mediated cycloisomerization of 3-C-propargyl-ribo- and allofuranose derivatives was investigated in detail to understand the influence of electronic factors on the regioselectivity (6-exo- vs 7-endo) of alkynol cycloisomerization leading either to a six- or seven-membered ring. In general, the 6-exo-dig mode of cyclization is facile and is independent of electronic factors. With some of the alkynols, a regioselective (7-endo?) hydration of the alkyne unit was observed and this has been attributed to the participation of C(3)-OH. When the C(3)-OH was protected as its benzyl ether, cycloisomerization of these alkynols occurred exclusively in a 6-exo-dig mode resulting in the corresponding [3.2.1]-bicyclic ketals. Additional control experiments conducted were in support of the participation of C(3)-OH in regioselective alkyne hydration. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Alkynol cycloisomerization, Bridged bicyclic ketal, Palladium, Sonogashira coupling, Sugar alkynol}, issn = {0040-4020}, doi = {10.1016/j.tet.2009.09.071}, author = {Ramana, C. V. and Induvadana, Boddeti and Srinivas, Burgula and Yadagiri, Kommagalla and Deshmukh, Madhusudhan N. and Gonnade, Rajesh G.} } @article { ISI:000316095000011, title = {Target cum flexibility: simple access to benzofuran conjugated sugar and nucleoside derivatives}, journal = {Tetrahedron Letters}, volume = {54}, number = {14}, year = {2013}, month = {APR}, pages = {1824-1827}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The [Pd]-catalyzed domino process comprising of the coupling of alkynes and o-iodophenol and the subsequent cyclization leading to benzofurans has been successfully applied on the sugar and nucleoside derived alkynes. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Benzofuran, carbohydrates, cyclization, Nucleoside, Palladium}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2013.01.089}, author = {Kommagalla, Yadagiri and Srinivas, Kolluru and Ramana, C. V.} }