Guanidine Hydrochloride → 8-Amino-1-methyl-4,5-dihydro-1H-1,7,9-triaza-cyclopenta[a]naphthalene-2,3-dicarboxylic acid 2-tert-butyl ester 3-ethyl ester

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Reaction Conditions

Reaction Steps

To a solution of 1-methyl-7-oxo-4,5,6,7-tetrahydro-1H-indole-2,3-dicarboxylic acid 2-tert-butyl ester 3-ethyl ester XXVIA (4.67 mmol) in DMF (20 mL), N,N-dimethylformamide di -tert-butyl acetal (2 mL) was added and the solution was stirred at 100° C. overnight. After cooling to rt guanidine hydrochloride (14 mmol) and K2CO3 (14 mmol) were added and the mixture was heated at 100° C. for 24 h. The organic solvent was evaporated to dryness. Chromatography on silica gel (AcOEt/hexane 1:1) afforded the title compound (80% yield). ESI (+) MS: m/z 373 (MH+). 1H NMR: 1.28 (t, J=7.07, 3H), 1.55 (s, 9H), 2.68 (t, J=7.80, 2H), 2.79 (t, J=7.80, 2H), 4.18 (s, 3H), 4.23 (q, J=7.07, 2H), 6.40 (bs, 2H), 7.97 (s, 1H).

Provenance & Evidence