1360924-07-7Relevant articles and documents
Decarboxylative allylation of glyoxylic acids with diallyl carbonate
Manjolinho, Filipe,Gruenberg, Matthias F.,Rodriguez, Nuria,Goossen, Lukas J.
, p. 4680 - 4683 (2012)
A catalyst system consisting of Pd(PPh3)4 and P(pTol)3 was found to effectively promote the intermolecular decarboxylative coupling of α-oxocarboxylic acids with diallyl carbonate to give α,β-unsaturated ketones. The key advantage of the new reaction protocol is that preformation of the allyl esters is not required. The reaction is believed to proceed via phosphane-mediated decarboxylation of the α-oxocarboxylates, leading to acyl anion equivalents that are allylated within the coordination sphere of the palladium catalyst. Under the reaction conditions, the double bond then migrates into conjugation with the carbonyl group. Copyright
Catalytic Dynamic Kinetic Resolutions in Tandem to Construct Two-Axis Terphenyl Atropisomers
Beleh, Omar M.,Miller, Edward,Toste, F. Dean,Miller, Scott J.
supporting information, p. 16461 - 16470 (2020/10/26)
The defined structure of molecules bearing multiple stereogenic axes is of increasing relevance to materials science, pharmaceuticals, and catalysis. However, catalytic enantioselective approaches to control multiple stereogenic axes remain synthetically challenging. We report the catalytic synthesis of two-axis terphenyl atropisomers, with complementary strategies to both chlorinated and brominated variants, formed with high diastereo-and enantioselectivity. The chemistry proceeds through a sequence of two distinct dynamic kinetic resolutions: first, an atroposelective ring opening of Bringmann-type lactones produces a product with one established axis of chirality, and second, a stereoselective arene halogenation delivers the product with the second axis of chirality established. In order to achieve these results, a class of Br?nsted basic guanidinylated peptides, which catalyze an efficient atroposelective chlorination, is reported for the first time. In addition, a complementary bromination is reported, which also establishes the second stereogenic axis. These bromo-terphenyls are accessible following the discovery that chiral anion phase transfer catalysis by C2-symmetric phosphoric acids allows catalyst control in the second stereochemistry-determining event. Accordingly, we established the fully catalyst-controlled stereodivergent synthesis of all possible chlorinated stereoisomers while also demonstrating diastereodivergence in the brominated variants, with significant levels of enantioselectivity in all cases.
Synthesis of α,β-unsaturated ketones by Pd-catalyzed decarboxylative allylation of α-oxocarboxylates
Rodriguez, Nuria,Manjolinho, Filipe,Gruenberg, Matthias F.,Goossen, Lukas J.
, p. 13688 - 13691 (2012/01/15)
A palladium/p-tolylphosphine system has been developed that catalyzes the extrusion of carbon dioxide from α-oxocarboxylic acid allyl esters, leading to α,β-unsaturated ketones (see scheme). The palladium complex activates the substrate and mediates the carbon-carbon bond formation to give allyl ketones, and subsequent double bond shift to the α,β position. The actual decarboxylation step with formation of the acyl nucleophile is promoted by phosphine.
