99196-24-4Relevant academic research and scientific papers
Development of a catalytic enantioselective synthesis of the guanacastepene and heptemerone tricyclic core
Harned, Andrew M.,Stoltz, Brian M.
, p. 3166 - 3177 (2019)
For nearly two decades, synthetic chemists have been fascinated by the structural complexity and synthetic challenges afforded by the guanacastepene and heptemerone diterpenoids. Numerous synthetic approaches to these compounds have been reported, but to date the application of enantioselective catalysis to this problem has not been realized. Herein we report an enantioselective synthesis of an advanced intermediate corresponding to the tricyclic core common to the guanacastepenes and heptemerones. Highlights of this work include sequential Pd-catalyzed decarboxylative allylic alkylation reactions to generate the two all carbon quaternary stereocenters, the use of ring-closing metathesis to close the A ring in the presence of a distal allyl sidechain, and a regio- and diastereoselective oxidation of a trienol ether to introduce oxygenation on the A ring.
Palladium-catalyzed asymmetric alkylation in the synthesis of cyclopentanoid and cycloheptanoid core structures bearing all-carbon quaternary stereocenters
Hong, Allen Y.,Bennett, Nathan B.,Krout, Michael R.,Jensen, Thomas,Harned, Andrew M.,Stoltz, Brian M.
scheme or table, p. 10234 - 10248 (2012/01/03)
General catalytic asymmetric routes toward cyclopentanoid and cycloheptanoid core structures embedded in numerous natural products have been developed. The central stereoselective transformation in our divergent strategies is the enantioselective decarboxylative alkylation of seven-membered β-ketoesters to form α-quaternary vinylogous esters. Recognition of the unusual reactivity of β-hydroxyketones resulting from the addition of hydride or organometallic reagents enabled divergent access to γ-quaternary acylcyclopentenes through a ring contraction pathway or γ-quaternary cycloheptenones through a carbonyl transposition pathway. Synthetic applications of these compounds were explored through the preparation of mono-, bi-, and tricyclic derivatives that can serve as valuable intermediates for the total synthesis of complex natural products. This work complements our previous work with cyclohexanoid systems.
Pyrazolopyridine cycloalkanones and process for their preparation
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, (2008/06/13)
Novel tetrahydropyrazolo-[3,4-b]quinolinones, cyclopenta[b]pyrazolo-[4,3-e]pyridinones and cyclohepta[b]-pyrazolo[4,3-e]pyridinones, useful as anxiolytics having reduced side effects, are disclosed, including methods of preparation, pharmaceutical compositions containing them and intermediates used in their preparation.
