Methanol, magnesium salt (2:1) → 9-(3-Chloro-4-fluorobenzyl)-7-hydroxy-3,4,10,11-tetrahydro-2H-pyrazino[2,1-a]-2,6-naphthyridine-1,6,8(9H)-trione

Participants

Reaction Conditions

Reaction Steps

A mixture of 6-(3-chloro-4-fluorobenzyl)-3,4-dihydroxy-N,N-dimethyl-5-oxo-5,6,7,8-tetrahydro-2,6-naphthyridine-1-carboxamide (1.00 g, 2.63 mmol; Example 1, Step 9) and magnesium methoxide in methanol (13.1 mL, 6-10% methanol solution available from Aldrich) in DMSO (26 mL) was heated at 60° C. for one hour. Methanol was exhaustively removed under vacuum over 45 minutes. The resulting DMSO solution was treated with tert-butyl (2-bromoethyl)carbamate (2.94 g, 13.13 mmol) and stirred at 60° C. under an atmosphere of nitrogen for one hour. The reaction mixture was diluted with ethyl acetate and washed successively with 10% sodium thiosulfate and brine. The organic extract was dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was purified by reverse phase high pressure liquid chromatography. Collection and lyophilization of appropriate fractions provided the title compound.

Provenance & Evidence