Szcmmury Complexes of Maya-tetraphenylporphinzinc in which one and two of the phenyl rings are n-substituted with tricarbonylchromium groups have been prepared and characterized.ELECTRON distribution in metallo-porphyrins is of considerable importance in many life processes, for example in photosynthesis and cell energy transfer (cytochromes in particular). We have prepared two complexes of a series the study of which should help the understanding of electron distribution and transfer in the porphyrin system. These are complexes of aPy8-tetraphenylporphinzinc, Zn(tpp) , in which a tricarbonylchromium group is attached to one and two of the phenyl rings.The complexes were prepared by allowing Cr(CO), and Zn(tpp) to react in refluxing di-n-butyl ether in an atmosphere of pure nitrogen. Chromatography of the resulting material on Florisil yielded three bands, a red band, Zn(tpp) , a brownish-green band, (I), and a greenish-brown band, (11). Details of the spectra of these compounds are given in the Table . The n.m.r. assignments follow those of Webb is typical of tricarbonyl-n-arenechromiums. The n.m.r. spectra of both compounds consist of three main areas, @
The preparative value of the I-(phenylsulfonyl) N-blocking and directing group for the synthesis of 3-acylpyrroles has been further evaluated. Acetylation and benzoylation are strongly regiospecific and give good yields. However, the regiospecificity is not general and other substitution reactions give mixtures of 2-and 3-substitution or even mostly 2-substitution. Friedel and Crafts rert-butylation gives 3-rerr-butyl-I-(phenylsulfonyl)pyrrole and provides a useful route to rert-butylpyrrole, but ethylation and isopropylation give mixtures. Acylations of 2-and 3-alkyl-I-(phenylsulfonyl)pyrroles show little evidence of useful regiospeeifieity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.