One-pot preparation of a benzoisoindolenine salt from a tetrahydronaphthalic anhydride
A method of effecting a one-pot conversion of a tetrahydronaphthalic anhydride to a benzisoindolenine salt is provided. The method comprises heating the tetrahydronaphthalic anhydride with a reagent mixture comprising ammonium nitrate.
1. A method of effecting a one-pot conversion of a tetrahydronaphthalic anhydride of formula (I):
to a salt of a benzisoindolenine of formula (II):
said method comprising heating said tetrahydronaphthalic anhydride of formula (I) with a reagent mixture comprising ammonium nitrate,
wherein:
R 1 , R 2 , R 3 and R 4 are each independently selected from hydrogen, hydroxyl, C 1-20 alkyl, C 1-20 alkoxy, amino, C 1-20 alkylamino, di(C 1-20 alkyl)amino, halogen, cyano, thiol, C 1-20 alkylthio, nitro, C 1-20 alkylcarboxy, C 1-20 alkylcarbonyl, C 1-20 alkoxycarbonyl, C 1-20 alkylcarbonyloxy, C 1-20 alkylcarbonylamino, C 5-20 aryl, C 5-20 arylalkyl, C 5-20 aryloxy, C 5-20 arylalkoxy, C 5-20 heteroaryl, C 5-20 heteroaryloxy, C 5-20 heteroarylalkoxy or C 5-20 heteroarylalkyl.
2. The method of claim 1 , wherein R 1 , R 2 , R 3 and R 4 are all hydrogen.
3. The method of claim 1 , wherein said salt of said benzisoindolenine of formula (II) is a nitrate salt.
4. The method of claim 1 , wherein said reagent mixture comprises at least 2 equivalents of ammonium nitrate with respect to said tetrahydronaphthalic anhydride.
5. The method of claim 1 , wherein said reagent mixture comprises urea.
6. The method of claim 1 , wherein said reagent mixture comprises at least one further ammonium salt.
7. The method of claim 5 , wherein said at least one further ammonium salt is selected from ammonium sulfate and ammonium benzenesulfonate.
8. The method of claim 1 , wherein said reagent mixture comprises a catalytic amount of ammonium molybdate.
9. The method of claim 1 , wherein said heating is within a temperature range of 150 to 200° C.
10. The method of claim 8 , wherein said heating is in the presence of solvent selected from the group comprising: nitrobenzene, diphenyl, diphenyl ether, mesitylene, anisole, phenetole, dichlorobenzene, trichlorobenzene and mixtures thereof.
11. The method of claim 1 , comprising the further step of liberating the corresponding benzisoindolenine from the salt of the benzisoindolenine of formula (II) using a base.