@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:000315321400011, title = {Metal-mediated alkynediol cycloisomerization: first and second generation formal total syntheses of didemniserinolipid B}, journal = {Tetrahedron}, volume = {69}, number = {7}, year = {2013}, month = {FEB}, pages = {1881-1896}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A formal total synthesis of didemniserinolipid B was developed by employing a regioselective metal-mediated 6-endo-dig alkynol-cycloisomerization reaction. Two routes for the synthesis of key Burke{\textquoteright}s intermediate have been developed. Our initial approach involved the introduction of a C-17-allcynol followed by Pd-mediated cycloisomerization and then coupling with the serinol unit prior to the introduction of an alpha,beta-unsaturated ester unit through selective oxidation of 1 degrees-OH followed by a two-carbon Wittig homologation. Alternatively, the second generation strategy featuring the serinol coupling with the C-17-alkynol followed by alkyne addition to the epoxide and subsequent Au-mediated cycloisomerization of an acetonide protected alkynediol unit has been executed. This approach has avoided several late stage protection-deprotection events. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Alkynol-cycloisomerization, Bicyclic ketal, Gold catalysis, Palladium catalysis, Zipper reaction}, issn = {0040-4020}, doi = {10.1016/j.tet.2012.12.045}, author = {Das, Shyamsundar and Induvadana, Boddeti and Ramana, C. V.} }