853400-94-9Relevant academic research and scientific papers
Radical-Cation Vinylcyclopropane Rearrangements by TiO2Photocatalysis
Maeta, Naoya,Kamiya, Hidehiro,Okada, Yohei
, p. 6551 - 6566 (2020/07/14)
Radical cation vinylcyclopropane rearrangements by TiO2 photocatalysis in lithium perchlorate/nitromethane solution are described. The reactions are triggered by oxidative single electron transfer, which is followed by immediate ring-opening of the cyclopropanes to generate distonic radical cations as unique reactive intermediates. This approach can also be applied to vinylcyclobutane, leading to the construction of six-membered rings. A stepwise mechanism via distonic radical cations is proposed based on preliminary mechanistic studies, which is supported by density functional theory calculations.
Formal homo-nazarov and other cyclization reactions of activated cyclopropanes
De Simone, Filippo,Saget, Tanguy,Benfatti, Fides,Almeida, Sofia,Waser, Jerome
supporting information; experimental part, p. 14527 - 14538 (2012/02/04)
The Nazarov cyclization of divinyl ketones gives access to cyclopentenones. Replacing one of the vinyl groups by a cyclopropane leads to a formal homo-Nazarov process for the synthesis of cyclohexenones. In contrast to the Nazarov reaction, the cyclization of vinyl-cyclopropyl ketones is a stepwise process, often requiring harsh conditions. Herein, we describe two different approaches for further polarization of the three-membered ring of vinyl-cyclopropyl ketones to allow the formal homo-Nazarov reaction under mild catalytic conditions. In the first approach, the introduction of an ester group α to the carbonyl on the cyclopropane gave a more than tenfold increase in reaction rate, allowing us to extend the scope of the reaction to non-electron-rich aryl donor substituents in the β position to the carbonyl on the cyclopropane. In this case, a proof of principle for asymmetric induction could be achieved using chiral Lewis acid catalysts. In the second approach, heteroatoms, especially nitrogen, were introduced β to the carbonyl on the cyclopropane. In this case, the reaction was especially successful when the vinyl group was replaced by an indole heterocycle. With a free indole, the formal homo-Nazarov cyclization on the C3 position of indole was observed using a copper catalyst. In contrast, a new cyclization reaction on the N1 position was observed with BrAnsted acid catalysts. Both reactions were applied to the synthesis of natural alkaloids. Preliminary investigations on the rationalization of the observed regioselectivity are also reported.
Catalytic formal homo-Nazarov cyclization
De Simone, Filippo,Andres, Julien,Torosantucci, Riccardo,Waser, Jerome
supporting information; experimental part, p. 1023 - 1026 (2009/07/18)
The first catalytic method for the cyclization of vinyl-cyclopropyl ketones (formal homo-Nazarov reaction) is reported. Starting from activated cyclopropanes, heterocyclic, and carbocyclic compounds were obtained under mild conditions using Bronsted acid catalysts. Preliminary investigation of the reaction mechanism indicated a stepwise process.
Discovery of +(2-{4-[2-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)ethoxy]phenyl}-cyclopropyl)acetic acid as potent and selective αvβ3 inhibitor: Design, synthesis, and optimization
Nagarajan, Srinivasan R.,Lu, Hwang-Fun,Gasiecki, Alan F.,Khanna, Ish K.,Parikh, Mihir D.,Desai, Bipinchandra N.,Rogers, Thomas E.,Clare, Michael,Chen, Barbara B.,Russell, Mark A.,Keene, Jeffery L.,Duffin, Tiffany,Engleman, V. Wayne,Finn, Mary B.,Freeman, Sandra K.,Klover, Jon A.,Nickols, G. Alan,Nickols, Maureen A.,Shannon, Kristen E.,Steininger, Christina A.,Westlin, William F.,Westlin, Marisa M.,Williams, Melanie L.
, p. 3390 - 3412 (2008/02/08)
The integrin αvβ3 is expressed in a number of cell types and is thought to play a major role in several pathological conditions. Various small molecules that inhibit the integrin have been shown to suppress tumor growth and retinal a
