1,5-Naphthalenedisulfonic acid → (3aRS,4SR,9aSR)-3a,4,9,9a-tetrahydro-4-phenyl-benz[f]isoindoline-2-propionic acid

Participants

Reaction Steps

10 g of (3aRS,4SR,9aSR)-3a,4,9,9a-tetrahydro-4-phenyl-benz[f]isoindoline-2-propionic acid methyl ester are heated to the boil at reflux in 50 cc of 2 N hydrochloric acid for 5 hours. The solution is then concentrated by evaporation, the residue is dissolved in water, the pH of the solution is adjusted to 1 with caustic soda solution, and 1 equivalent of 1,5-naphthalene disulphonic acid is added, whereby the bis-1,5-naphthalene-disulphonate salt form of the title compound is obtained in sticky form. The supernatant water is poured off and the resin is triturated with acetone, whereby it crystallizes. M.P. 193°-195°.

Provenance & Evidence