Michal Achmatowicz

Practical synthesis of a p38 MAP kinase inhibitor.

p38 MAP kinase inhibitors have attracted considerable interest as potential agents for the treatment of inflammatory diseases. Herein, we describe a concise and efficient synthesis of inhibitor 1 that is based on a phthalazine scaffold. Highlights of our approach include a practical synthesis of a 1,6-disubstituted phthalazine building block 24 as well as the one-pot formation of boronic acid 27. Significant synthetic work to understand the reactivity principles of the intermediates helped in selection of the final synthetic route. Subsequent optimization of the individual steps of the final sequence led to a practical synthesis of 1.

Selective ortho methylation of nitroheteroaryls by vicarious nucleophilic substitution.

An efficient and scalable three-step one-pot approach to 6-methyl-5-nitroisoquinoline (1) from inexpensive 5-nitroisoquinoline, utilizing the vicarious nucleophilic substitution (VNS) as a key step, is described. The optimized reaction conditions can be applied to a limited number of other aromatic and heteroaromatic nitro compounds. Attempts to understand the observed selectivity in the VNS step led to the discovery of two new reaction pathways under VNS conditions, one leading to an isoxazole and the other resulting in the formal cyclopropanation of an aromatic nitro compound.

Telescoped Process to Manufacture 6,6,6-Trifluorofucose via Diastereoselective Transfer Hydrogenation: Scalable Access to an Inhibitor of Fucosylation Utilized in Monoclonal Antibody Production

IgG1 monoclonal antibodies with reduced glycan fucosylation have been shown to improve antibody-dependent cellular cytotoxicity (ADCC) by allowing more effective binding of the Fc region of these proteins to T cells receptors. Increased in vivo efficacy in animal models and oncology clinical trials has been associated with the enhanced ADCC provided by these engineered mAbs. 6,6,6-Trifluorofucose (1) is a new inhibitor of fucosylation that has been demonstrated to allow the preparation of IgG1 monoclonal antibodies with lower fucosylation levels and thus improve the ADCC of these proteins. A new process has been developed to support the preparation of 1 on large-scale for wide mAb manufacture applications. The target fucosylation inhibitor (1) was synthesized from readily available d-arabinose in 11% overall yield and >99.5/0.5 dr (diastereomeric ratio). The heavily telescoped process includes seven steps, two crystallizations as purification handles, and no chromatography. The key transformation of the sequence involves the diastereoselective preparation of the desired trifluoromethyl-bearing alcohol in >9/1 dr from a trimethylsilylketal intermediate via a ruthenium-catalyzed tandem ketal hydrolysis-transfer hydrogenation process.

Syntheses and reactions of optically active α-aminoallenylstannanes and α-aminopropargylboranes

An efficient synthesis of α-aminoallenylstannane from propargyloxazolidinone has been developed. It undergoes reaction with aldehydes to give homopropargylic alcohols with high syn selectivity. Epoxides undergo a similar reaction preceded by rearrangement to the aldehyde. These alcohols were used in the synthesis of β-amino acids, azasugars, and deoxyaminohexoses. Imines underwent reaction with this stannane to give 1,2-diamines. The related propargylborane reacts with aldehydes to produce allenyl carbinols. The Co2(CO)6 complexes of propargyloxazolidinones were developed as an α-aminopropargyl cation equivalent.