Synthesis of Two Key Fragments of the Complex Polyhalogenated Marine Meroterpenoid Azamerone
A concise route toward two advanced fragments in the context of the total synthesis of the unique natural product azamerone is reported. Key synthetic features include the enantioselective synthesis of an epoxysilane and its Lewis-acid-induced cyclization and the installation of the pyridazine ring via a formylation/condensation sequence. This route provides strategic insights into the chemistry of phthalazinediols, facilitating synthetic approaches toward this class of natural products.
Schnell, Simon D.,Linden, Anthony,Gademann, Karl
p. 1144 - 1147
(2019/05/16)
Synthesis of β-Lactams by Palladium(0)-Catalyzed C(sp3)?H Carbamoylation
A general and user-friendly synthesis of β-lactams is reported that makes use of Pd0-catalyzed carbamoylation of C(sp3)?H bonds, and operates under stoichiometric carbon monoxide in a two-chamber reactor. This reaction is compatible with a range of primary, secondary and activated tertiary C?H bonds, in contrast to previous methods based on C(sp3)?H activation. In addition, the feasibility of an enantioselective version using a chiral phosphonite ligand is demonstrated. Finally, this method can be employed to synthesize valuable enantiopure free β-lactams and β-amino acids.
Dailler, David,Rocaboy, Ronan,Baudoin, Olivier
supporting information
p. 7218 - 7222
(2017/06/13)
Enantiomerically enriched tris(boronates): Readily accessible conjunctive reagents for asymmetric synthesis
The catalytic enantioselective diboration of vinyl boronate esters furnishes chiral tris(boronates) in a selective fashion. Subsequent deborylative alkylation occurs in a diastereoselective fashion, both for intermolecular and intramolecular processes.
Coombs, John R.,Zhang, Liang,Morken, James P.
supporting information
p. 16140 - 16143
(2015/01/09)
Scope and mechanism of the Pt-catalyzed enantioselective diboration of monosubstituted alkenes
The Pt-catalyzed enantioselective diboration of terminal alkenes can be accomplished in an enantioselective fashion in the presence of chiral phosphonite ligands. Optimal procedures and the substrate scope of this transformation are fully investigated. Reaction progress kinetic analysis and kinetic isotope effects suggest that the stereodefining step in the catalytic cycle is olefin migratory insertion into a Pt-B bond. Density functional theory analysis, combined with other experimental data, suggests that the insertion reaction positions platinum at the internal carbon of the substrate. A stereochemical model for this reaction is advanced that is in line both with these features and with the crystal structure of a Pt-ligand complex.
Coombs, John R.,Haeffner, Fredrik,Kliman, Laura T.,Morken, James P.
supporting information
p. 11222 - 11231
(2013/08/23)
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