97037-95-1Relevant articles and documents
Bridgehead Azides, 5. - Photolysis of 9-Azidotriptycenes. - Addition of Methanol or Water to Severely Strained Intermediate Bridgehead Imines
Quast, Helmut,Eckert, Philipp,Seiferling, Bernhard
, p. 696 - 707 (2007/10/02)
The 9-lithiotriptycenes 7 are allowed to react with (4-methylphenyl)sulfonyl azide affording the lithiotriazenes 8 which on thermolysis in boiling benzene produce the 9-azidotriptycenes 10 in high yields.Irradiation of the azidotriptycenes 10 in methanol solution induces loss of molecular nitrogen with concomittant formation of the azahomotriptycenes 12.The azahomotriptycene 12a is very sensitive towards acid and undergoes acid-catalyzed or photochemical cleavage of its azepine ring producing the 9-methoxy-10-phenylanthracene 15.In contrast, the azahomotriptycene 12bis much more stable, yielding the 10-methyl-10-phenylanthrone 14 on ring opening of its azepine ring only in hot methanol/0.5 N hydrochloric acid.The anthrone 14 is formed in high yield on irradiation of the azidotriptycene 10b in aqueous dioxane solution.The amino group of the anthrone 14 is removed via diazotation followed by reduction of the diazonium salt with hypophosphorous acid.This sequence yields the known 10-methyl-10-phenylanthrone (13).The formation of the azahomotriptycenes 12 is interpreted in terms of the severely strained bridgehead imines 11 as intermediates in the azidotriptycene photolysis which are trapped by the solvent methanol.
