The pursuit of two independent projects in indole synthesis, targeting members of the dragmacidin family of phosphatase inhibitors in one case and the anticancer sponge principle perophoramidine in the other, is proposed. In each case, development of novel methodology for the efficient preparation of the parent ring systems is followed by planned total syntheses of the natural products dragmacidin E and perophoramidine, as well as rationally designed structural analogues of the former species as part of an SAR study. Selective phosphatase inhibition has been proposed as a means of therapeutic intervention in a host of diseases, from Parkinson's to cancer. One key unsolved problem in this area is the identification of small molecules that display significant selectivity for inhibition of the phosphatase PP1 over the analogous phosphatase PP2A. Certain dragmacidins are reported to exhibit such preferences, and the program of synthesis outlined in this proposal is designed to provide molecules for probing the structural basis for this selectivity. A new approach to C(3)/C(4)-cycloheptane-bridged indoles that features sequential Witkop and Dieckmann cyclizations is at the core of the synthesis strategy for these structurally novel compounds. The perophoramidine work will provide useful amounts of this scarce sponge-derived natural product to aid in further evaluation of its anti-cancer properties. This synthesis route extends from a new approach to spirocyclic oxindole derivatives that utilizes an oxidative cyclization of an indolic substrate. Addressing long- standing challenges in indole oxidative cyclization chemistry, such as a lack of regioselective bond formation and product (over)oxidation, are within the purview of the methodology proposed herein. The use of a new variant of the Pummerer reaction to control both oxidation level and reaction site within the indole nucleus forms the basis of this chemistry.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM072572-04S3
Application #
8119361
Study Section
Medicinal Chemistry Study Section (MCHA)
Program Officer
Hagan, Ann A
Project Start
2006-02-09
Project End
2012-01-31
Budget Start
2009-02-01
Budget End
2012-01-31
Support Year
4
Fiscal Year
2010
Total Cost
$77,229
Indirect Cost
Name
Pennsylvania State University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
003403953
City
University Park
State
PA
Country
United States
Zip Code
16802
Feldman, Ken S; Antoline, Joshua F (2013) Synthesis studies on the Melodinus alkaloid meloscine. Tetrahedron 69:1434-1445
Feldman, Ken S; Antoline, Joshua F (2012) Allenyl azide cycloaddition chemistry: application to the total synthesis of (±)-meloscine. Org Lett 14:934-7
Feldman, Ken S; Ngernmeesri, Paiboon (2012) Total Synthesis of (±)-Dragmacidin E: Problems Solved and Lessons Learned. Synlett 23:1882-1892
Feldman, Ken S; Ngernmeesri, Paiboon (2011) Total synthesis of (±)-dragmacidin E. Org Lett 13:5704-7
Feldman, Ken S; Ngernmeesri, Paiboon (2010) Dragmacidin E synthesis studies. Preparation of a model heptacyclic core structure. Org Lett 12:4502-5
Faza, Olalla Nieto; Feldman, Ken S; Lopez, Carlos Silva (2010) Cyclization Cascade of Allenyl Azides: Synergy Between Theory and Experiment. Curr Org Chem 14:1646-1657
Feldman, Ken S; Hester 2nd, D Keith; Iyer, Malliga R et al. (2009) Allenyl azide cycloaddition chemistry. 2,3-cyclopentennelated indole synthesis through indolidene intermediates. J Org Chem 74:4958-74
Feldman, Ken S; Hester 2nd, D Keith; Lopez, Carlos Silva et al. (2008) Allenyl azide cycloaddition chemistry. photochemical initiation and CuI mediation leads to improved regioselectivity. Org Lett 10:1665-8
Lopez, Carlos Silva; Faza, Olalla Nieto; Feldman, Ken S et al. (2007) Cyclization cascade of allenyl azides: a dual mechanism. J Am Chem Soc 129:7638-46
Feldman, Ken S; Iyer, Malliga R; Hester 2nd, D Keith (2006) Allenyl azide cycloaddition chemistry. Synthesis of annelated indoles from 2-(allenyl)phenyl azide substrates. Org Lett 8:3113-6