Anthracen-9,10-imines deamination

In the 7-azabicyclo[2.2.1]heptadiene series there is as yet no instance known of aromatization by deamination such as occurs with some naphthalen-l,4-imine and anthracen-9,10-imine derivatives (see Sections III, H and IV, D). On the other hand, a close parallel exists between those reactions and some instances of aromatization of bicyclo[2.2.1] structures by loss of a heavier heteroatom from the 7-position, e.g., 70 71. 1,2,3,4,5-Pentaphenylphosphole reacts with dimethyl acetyl-... 

The formation of anthracene in reactions of 185 and 186 with benzyne, which was unexplained by Wittig et aZ., possibly is due to an alternative reaction of the intermediate zwitterion (202) with another molecule of benzjme or with a benzyne precursor. Benzyne reacted with the isoindole (206) to give the tetramethyltriptycene (208) and, in a separate run using excess of the benzyne precursor, W-benzylcarbazole. The latter product would appear to be made up of the iV-benzyl group from an intermediate anthracen-9,10-imine (207) and two molecules of benzyne. Mass spectral evidence also implicated the adduct 207, and the formation of 208 was attributed to benzyne-induced deamination of 207 to 1,4,9,10-tetramethylanthracene, which was trapped by further addition of benzyne across the 9- and 10-positions. 

An interesting deamination of naphthalene- 1,4-imine 169 and anthracene-9,10-imine with PTC-generated dichlorocarbene was reported in 1981.265... 

N-phenylation. The further reaction of 87 and 88 with benzyne to give 9-aminoanthracene derivatives 91 (cf. the mechanism outlined in Scheme 12) is blocked by the presence of substituents at the bridgehead positions as in 86. Anthracene (9%) is also produced from the reaction of 87 with benzyne,48 and the formation of the tetramethyltriptycene 93 from benzyne and the isoindole 92 is attributed to a similar deamination of an intermediate anthracen-9,10-imine.68 Deamination of 86 and 87 is more conveniently accomplished by treatment with hydrogen peroxide.72... 

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