Advances in Lewis Acid Controlled Carbon−Carbon Bond-Forming Reactions Enable a Concise and Convergent Total Synthesis of Bullatacin
摘要:
Lewis acids control regioselectivity in the alkylation of epi-chlorohydrin and the stereochemistry of an alkyne addition to set the C24/C23 anti relationship. These advances facilitate an efficient total synthesis of bullatacin in 13.3% overall yield from commercial starting materials.
Advances in Lewis Acid Controlled Carbon−Carbon Bond-Forming Reactions Enable a Concise and Convergent Total Synthesis of Bullatacin
摘要:
Lewis acids control regioselectivity in the alkylation of epi-chlorohydrin and the stereochemistry of an alkyne addition to set the C24/C23 anti relationship. These advances facilitate an efficient total synthesis of bullatacin in 13.3% overall yield from commercial starting materials.
Increased Yields and Simplified Purification with a Second-Generation Cobalt Catalyst for the Oxidative Formation of <i>trans</i>-THF Rings
作者:Cory Palmer、Nicholas A. Morra、Andrew C. Stevens、Barbora Bajtos、Ben P. Machin、Brian L. Pagenkopf
DOI:10.1021/ol9023375
日期:2009.12.17
The synthesis of a second-generation cobalt catalyst for the formation of trans-THF products via the Mukaiyama aerobic oxidative cyclization is reported. Two procedures have been developed with the new water-soluble catalyst that give superior yields and greatly simplify purification compared to the previous catalysts.
Synthesis of 10 stereochemically distinct bis-tetrahydrofuran intermediates for creating a library of 64 asimicin stereoisomers
作者:Zhiyong Chen、Subhash C. Sinha
DOI:10.1016/j.tetlet.2009.08.082
日期:2009.11
Stereoselective synthesis of 10 unique bifunctional stereoisomeric adjacent bis-THF intermediates (R = Bz), including 5.1-5.4, 5.7-5.9, 5.11, and 5.15-5.16, of 16 possible compounds, is described. The key steps used in the synthesis of these compounds included the rhenium(VII) oxide-mediated and the Co(modP)(2)-catalyzed trans oxidative cyclizations (OCs), the OsO4-catalyzed cis OC, and the Williamson's type etherification reactions. The remaining six bis-THF intermediates (R = Bn) can be prepared from 5.7-5.9, 5.11, and 5.15-5.16 (R = Bz) in two steps, including protection of the free alcohol as benzyl ether followed by the benzoate deprotection. These intermediates should provide access to all 64 asimicin stereoisomers; and their analogs. (C) 2009 Published by Elsevier Ltd.