@article { ISI:000263152800005, title = {Formal synthesis of (+)-didemniserinolipid B employing a Pd-mediated 6-endo selective alkynediol cycloisomerization}, journal = {Tetrahedron Letters}, volume = {50}, number = {3}, year = {2009}, month = {JAN}, pages = {271-273}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Herein, we describe a concise assembly of central 6,8-dioxabicyclo[3,2,1]octane core of didemniserino-lipid by employing a Pd-mediated alkynediol cycloisomerization and a formal total synthesis of didemniserinolipid (C) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {Alkynol cycloisomerization, Bridged bicyclic ketal, Didemniserinolipid, Yamaguchi oxirane alkyne coupling, Zipper reaction}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2008.10.137}, author = {Ramana, C. V. and Induvadana, Boddeti} } @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:000268508900011, title = {Pd-mediated intramolecular ketalization of alkynediols: construction of the central [3.2.1]-bicyclic ketal core of cyclodidemniserinol trisulfate}, journal = {Tetrahedron Letters}, volume = {50}, number = {34}, year = {2009}, month = {AUG}, pages = {4844-4847}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A preliminary study dealing with the Pd-mediated alkynediol cycloisomerization to construct the central bicyclic ketal core of cyclodidemniserinol trisulfate is documented. (c) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Alkynol cycloisomerization, Bridged bicyclic ketal, Cyclodidemniserinol trisulfate, Yamaguchi oxirane-alkyne coupling}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2009.06.023}, author = {Ramana, C. V. and Mallik, Rosy and Sahoo, Gokarneswar} } @article {46697, title = {Attempted synthesis of central furopyran core of diocollettines A via a gold-catalyzed cascade 1,6-diyne cycloisomerization process}, journal = {Tetrahedron Letters}, volume = {61}, year = {2020}, month = {OCT }, pages = {152367}, type = {Article}, abstract = {

Herein, we describe an Au-catalyzed cascade diyne cycloisomerization process that was projected to construct the central furopyran bicyclic core of Diocollettines A. Our intended strategy for the annulation of the third thf ring is based on epoxidation and subsequent intramolecular acetalization. However, the initial alkynol cyclization occurred in an undesired 5-exo-dig mode, ultimately leading to an undesired furopyran. (C) 2020 Elsevier Ltd. All rights reserved.

}, keywords = {1, 6-Hexadiyne, Alkynol cycloisomerization, Diocollettines A, Gold-catalysis, Total synthesis}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2020.152367}, author = {Mullapudi, Venkannababu and Ramana, V, Chepuri} }