Pierre-Georges Echeverria

Synthetic strategy toward the C44-C65 fragment of mirabalin.

A convergent and flexible stereoselective synthesis of one isomer of the C44-C65 fragment of mirabalin is described. The key steps include organocatalytic aldolization, ruthenium-catalyzed asymmetric hydrogenation, amide formation, Marshall stereoselective allenylation, and the Nozaki-Hiyama-Kishi reaction.

Heck Coupling Using a Vinyliodo-MIDA Boronate: An Efficient and Modular Access to Polyene Frameworks

A simple Heck coupling between an alkenyl iodo-boronate and a variety of terminal olefins is disclosed. This method gives access to a wide range of dienic moieties including valuable bis-functionalized dienes. The synthetic potential of the coupling reaction is demonstrated by a short and modular preparation of several tetraenic compounds.

Asymmetric Transfer Hydrogenation of (Hetero)arylketones with Tethered Rh(III)–N-(p-Tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine Complexes: Scope and Limitations

A series of new tethered Rh(III)/Cp* complexes containing the N-(p-tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine ligand have been prepared, characterized, and evaluated in the asymmetric transfer hydrogenation (ATH) of a wide range of (hetero)aryl ketones. The reaction was performed under mild conditions with the formic acid/triethylamine (5:2) system as the hydrogen source and provided enantiomerically enriched alcohols with good yields and high to excellent enantioselectivities. Although the nature of the substituents on the phenyl tethering ring did not alter the stereochemical outcome of the reaction, complexes bearing electron-donating groups exhibited a higher catalytic activity than those having electron-withdrawing groups. A scale-up of the ATH of 4-chromanone to the gram scale quantitatively delivered the reduced product with excellent enantioselectivity, demonstrating the potential usefulness of these new complexes.

Asymmetric transfer hydrogenation of α-amino β-keto ester hydrochlorides through dynamic kinetic resolution

The development of Ru-catalyzed asymmetric transfer hydrogenation of α-amino β-keto ester hydrochlorides is described. The reaction proceeds through dynamic kinetic resolution to afford anti β-hydroxy α-amino esters with good diastereomeric ratios and high enantioselectivities.

Synthetic Studies toward the C14–C29 Fragment of Mirabalin

A convergent synthesis of one isomer of the C14-C29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule.