4,7-Phenanthroline → 5-Methoxy-4,7-phenanthroline

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Reaction Steps

Some phenanthrolines are very reluctant to undergo the usual basic oxidative rearrangement to the corresponding diazafluorenone. This is true of 4,7-phenanthroline, for instance. In this case, one uses 2-methoxyparaphenylenediamine in a double Skraup synthesis to produce the enolether, 5-methoxy-4,7-phenanthroline (150). Reaction of it with concentrated sulfuric acid and fuming nitric acid yields 4,7-phenanthrolin-5,6-quinone (151). The quinone undergoes oxidative rearrangerent to produce 1,8-diazafluoren-9-one (152). Hydrazine reduction produces 1,8-diazafluorene (153) which is alkylated to the target compound, 9,9-bis(4-pyridinylmethyl)-1,8-diazafluorene (154). Other diazafluorenes produced by this method include 1,5-diazafluorene, (Scheme 67, 157), 1,6-diazafluorene, 2,5-diazafluorene, 3,5-diazafluorene, and 4,5-diazafluorene. See references for Scheme 64 and: French patent 382 542; French patent 1,369,626, U.S. Pat. No. 2,640,830, Swiss patent 275,433. ##STR87##

Provenance & Evidence