NOTES
629 6
Vol. 74
The Reaction of Thyroxine with Aromatic Isocyanates
group, free to be converted to a quinoid form is, essential for thyroxine activity, even, as in our case, despite the amino substitution with the relatively BY ALAN Ronmiav AND 11' R F R A ~ K S large group, 1,2,3,6-dibenzanthranyl-9-ureido-. RECEIL E D Jur 'i' 7, 1952 Further evidence that linkage occurs preferenDuring the investigation of the influence of thy- tially a t the amino group rather than a t the phenolic roxine on the chemical carcinogenesis as induced by hydroxyl resulted from the Sorenson titration l2 of I ,2,5,6-dibenzanthra~enel>~ and 3,4-benzpyrene, a the thyroxine and the thyroxine derivatives. The stable compound containing both the thvroxine and sodium salt of d,l-thyroxine was converted to d,lthe 1,2,5,6-dibenzanthrCxenemolecules essentially thyroxine by treatment with ethanolic acetic acid. in-- ~ Forinol titration of this material gave almost the intact was desired. In our previous s t ~ d i e s ~ volving these carcinogenic hydrocarbons, the reac- theoretical value for free amino group nitrogen. tion of the isocyanate (I) with the amino com- Conversion of the sodium salt of either phenylurepounds (11) to form various ureitlo compounds (111) idothyroxine (IIIa) or lJ2,5,6-dibenzanthranyl-9was utilized. ureidothyroxine (IIIb) to the corresponding acid with ethanolic acetic acid C5HD,N gave a compound with __ ___ R--;\=C=O 7 HiSII? I almost zero free arnino I 11 I group nitrogen. a, R = CsHl a , Rl = R a = H O
