
%0 Journal Article
%A Clezy, PS 
%A Fookes, CJR 
%A Sternhell, S 
%T The chemistry of pyrrolic compounds. XL. A new synthesis of protoporphyrins III and XIII and a <sup>1</sup>H N.M.R. study of the preferred pathway of electron delocalization in the porphyrin macrocycle
%J Australian Journal of Chemistry
%D 1978/03/01
%V 31
%N 3
%P 639-648
%K 
%R https://doi.org/10.1071/CH9780639
%U https://www.publish.csiro.au/paper/CH9780639 
%X The synthesis of protoporphyrins III and XIII as the dimethyl esters has been completed by an oxidative cyclization of biladiene-ac intermediates. Protoporphyrin III has been converted into deuteroporphyrin III and measurements of the proton coupling constant in the allylic unit, CH3-C=C-H, of this latter porphyrin point to the double bond of this system having a significantly diminished bond order. This finding is in accord with the view that the &#960;-electron delocalization pathway in the porphyrin macrocycle involves the periphery of the molecule. 
