Synthesis of N-Allyloxycarbonyl 3,5-Dihydroxyphenylglycine via Photochemical Wolff Rearrangement-Nucleophilic Addition Sequence in a Micro-Flow Reactor

In this study, two practical and scalable procedures were developed for the synthesis of N-arylacetyl oxazolidinone, which is an intermediate for the preparation of N-allyloxylcarbonyl 3,5-dihydroxyphenylglycine. The key sequence in the developed procedures was a photochemical Wolff rearrangement-nucleophilic addition in a micro-flow reactor. A power-saving, inexpensive, and readily available light source (4-W portable ultraviolet [UV] lamp) along with a fluorinated ethylene propylene copolymer (FEP) tube was employed in the developed procedures. The first-generation procedure afforded the desired N-arylacetyl oxazolidinone in the highest yield. The yield was lower in the second-generation procedure, but it afforded pure N-arylacetyl oxazolidinone without column chromatographic purification. The use of the two parallel channel tube reactors enabled the gram-scale preparation of N-arylacetyl oxazolidinone. N-Allyloxylcarbonyl 3,5-dihydroxyphenylglycine was successfully prepared via the second-generation procedure.