Synthesis of N-Hydroxypyrazin-2(1H)-ones via Selective O-Debenzylation of 1-Benzyloxypyrazin-2(1H)-ones Using Flow Methodology

Abstract

This paper describes the selective and reproducible debenzylation of benzyloxypyrazinones using flow chemistry to yield N-hydroxypyrazinones. Flow methodology enabled us to avoid overreduction of the compounds to pyrazin-2 (1H)-ones.

Fine chemical syntheses under flow using SiliaCat catalysts

“…Most recently, De Borggraeve and co-workers described the selective and reproducible debenzylation of benzyloxypyrazinones (O-benzyl protected cyclic hydroxamates) over SiliaCat DPP-Pd to yield N-hydroxypyrazinones (Scheme 6) in a commercial flow microreactor (Chemtrix, model 3026). 29 The conversion is constant and complete in a wide range of temperatures (80-110 °C; above 60 °C ammonium formate efficiently decomposes in the presence of Pd) at a residence time of 14 s without losing selectivity for the formation of the desired product (N-OH form, 97-98%) with only 1-2% of the over-reduced pyrazin-2 product (N-H form).…”

Exploring SiliaCat Pd-DPP as a recyclable heterogeneous catalyst for the multi-batch direct heteroarylation polymerization for P(NDI2OD-T2)

“…When it comes to the reuse of a heterogeneous catalyst, a new catalyst (SiliaCat Pd-DPP) was developed by SiliCycle Incorporation and used in several fundamental transformations in organic chemistry (aryl halide to boronic acid pinacol esters, selective hydrogenation and O-debenzylation). [40][41][42] This catalyst is air-stable and does not require laborious handling under a carefully controlled atmosphere like that of a glove box, making it very feasible for handling industrial-scale reactions. 43 The SiliaCat Pd-DPP catalyst (structure shown in Fig.…”