The aim of this proposal is the development of new tandem bismuth-catalyzed inter- and intramolecular etherification reactions for the construction of non-adjacent and fused polycyclic ethers. The bismuth-catalyzed etherification reactions exhibit remarkable catalytic activity and unusual chemoselectivity, in which the direct addition to the carbonyl does not compete with the formation of the oxocarbenium ion. The bismuth catalysts are commercially availabile, inexpensive and non-toxic, making them ideal for many synthetic applications. The development of metal-catalyzed multi-component reactions for the rapid construction of complex polycyclic skeletons provides new and exciting opportunities for the synthesis of pharmacologically active agents. The specific areas of interest are summarized as follows: Tandem Stereoselective Intra- and Intermolecular Etherifications: The first section of the proposal will involve the development of tandem diastereoselective bismuth-catalyzed etherification reactions, through the sequencing of oxocarbenium ions, for the construction of non-adjacent tetrahydropyran rings. This methodology will then be applied to a convergent total synthesis of the potent antitumor agent leucascandrolide A. Annulation and Reductive Etherifications for Fused Polycyclic Ethers: The second aspect of the proposal details the development of new bismuth-catalyzed one-step annulation reactions in combination with ring-closing metathesis for the construction of polycyclic ethers. We will also examine the merit of temporary silicon-tethered ring-closing metathesis followed by the stereoselective bismuth-catalyzed reductive etherification, and its subsequent application to the DEFGH portion of the gambieric acids A-D. Finally, we will examine a series bismuth-catalyzed bis-reductive etherification reactions for the construction of linear fused polycyclic ethers.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM054623-07A2
Application #
6731751
Study Section
Medicinal Chemistry Study Section (MCHA)
Program Officer
Schwab, John M
Project Start
1997-05-01
Project End
2007-12-31
Budget Start
2004-01-01
Budget End
2004-12-31
Support Year
7
Fiscal Year
2004
Total Cost
$250,894
Indirect Cost
Name
Indiana University Bloomington
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
006046700
City
Bloomington
State
IN
Country
United States
Zip Code
47401
Evans, P Andrew; Grisin, Aleksandr; Lawler, Michael J (2012) Diastereoselective construction of syn-1,3-dioxanes via a bismuth-mediated two-component hemiacetal/oxa-conjugate addition reaction. J Am Chem Soc 134:2856-9
Evans, P Andrew; Sawyer, James R; Inglesby, Phillip A (2010) Regiodivergent ligand-controlled rhodium-catalyzed [(2+2)+2] carbocyclization reactions with alkyl substituted methyl propiolates. Angew Chem Int Ed Engl 49:5746-9
Evans, P Andrew; Andrews, William J (2005) Stereoselective construction of cis-2,6-disubstituted tetrahydropyrans via an intramolecular bismuth-mediated oxa-conjugate addition reaction. Tetrahedron Lett 46:5625-5627
Evans, P Andrew; Cui, Jian; Gharpure, Santosh J (2003) Stereoselective construction of cis-2,6-disubstituted tetrahydropyrans via the reductive etherification of delta-trialkylsilyloxy substituted ketones: total synthesis of (-)-centrolobine. Org Lett 5:3883-5
Evans, P Andrew; Cui, Jian; Gharpure, Santosh J et al. (2003) Stereoselective construction of cyclic ethers using a tandem two-component etherification: elucidation of the role of bismuth tribromide. J Am Chem Soc 125:11456-7
Evans, P Andrew; Cui, Jian; Gharpure, Santosh J et al. (2003) Enantioselective total synthesis of the potent antitumor agent (-)-mucocin using a temporary silicon-tethered ring-closing metathesis cross-coupling reaction. J Am Chem Soc 125:14702-3
Evans, P Andrew; Cui, Jian; Buffone, Gerald P (2003) Diastereoselective temporary silicon-tethered ring-closing-metathesis reactions with prochiral alcohols: a new approach to long-range asymmetric induction. Angew Chem Int Ed Engl 42:1734-7