skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Synthesis of internally alkylated azuliporphyrins
Internally alkylated azuliporphyrins were prepared by two different MacDonald-type “3 + 1” routes from 2-alkylazulitripyrranes or an N-methyltripyrrane. These carbaporphyrinoids were isolated as dihydrochlorides and the free-base forms proved to be unstable. Insertion of palladium(II) into a 23-methylazuliporphyrin was primarily associated with loss of the internal alkyl group, although palladium(II) carbaporphyrin byproducts arising from ring contraction and alkyl group migration were also isolated and characterized.  more » « less
Award ID(s):
1855240
PAR ID:
10186544
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Journal of Porphyrins and Phthalocyanines
Volume:
24
Issue:
05n07
ISSN:
1088-4246
Page Range / eLocation ID:
817 to 829
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. cid catalyzed condensation of N-alkyltripyrranes with trialdehydes derived from 1,3-cyclopentadiene or methyl-1,3-cyclopentadiene, followed by oxidation with aqueous ferric chloride solutions, gave 23-alkyl-21- carbaporphyrin-2-carbaldehydes in 22−27% yield together with weakly aromatic oxycarbaporphyrins. The carbaporphyrins reacted with palladium(II) acetate or nickel(II) acetate to give organometallic complexes but in both cases alkyl group migration took place to generate 21-alkyl derivatives. Although this type of reactivity had been observed previously for palladium complexes, this is the first time the phenomenon has been seen in nickel(II) carbaporphyrins. Reactions with nickel(II) acetate in refluxing DMF for longer time periods primarily led to decomposition but unusual byproducts were identified. These could be obtained in higher yields by reacting the carbaporphyrin aldehydes with 5 equiv of (bis(trifluoroacetoxy)iodo)benzene in the presence of grade 3 alumina. Decarbonylation and oxidation generate a trioxocyclopentane moiety that is embedded in the porphyrinoid macrocycle. The new system has strongly aromatic properties that are evident from the proton NMR spectra, nucleus independent chemical shift (NICS) calculations and anisotropy of induced ring current plots. 
    more » « less
  2. The synthesis of a range of PBP supported palladium pincer complexes with different alkyl ligands is described. The rates of CO2insertion into the alkyl group are quantified and rationalized based on the identity of the alkyl ligand. 
    more » « less
  3. Abstract A mild visible light‐induced palladium‐catalyzed alkyl Heck reaction of diazo compounds andN‐tosylhydrazones is reported. A broad range of vinyl arenes and heteroarenes with high functional group tolerance, as well as a range of different diazo compounds, can efficiently undergo this transformation. This method features Brønsted acid‐assisted generation of hybrid palladium C(sp3)‐centered radical intermediate, which allowed for new selective C−H functionalization protocol. 
    more » « less
  4. A series of 5-alkoxy-1,3-benzenedicarbaldehydes and related dimers were prepared in three steps from dimethyl 5-hydroxyisophthalate. Acid catalyzed condensation of the dialdehydes with a tripyrrane dicarboxylic acid, followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, afforded good yields of 3-alkoxybenziporphyrins, although dimeric tetraaldehydes failed to give isolatable porphyrinoid products. Proton NMR spectroscopy gave no indication of an aromatic ring current, but addition of trifluoroacetic acid resulted in the formation of dications that exhibited weakly diatropic characteristics. Spectroscopic titration with TFA demonstrated that stepwise protonation took place, generating monocationic and dicationic species. 3-Alkoxybenziporphyrins reacted with nickel(II) or palladium(II) acetate to give the related nickel(II) or palladium(II) complexes. These stable organometallic derivatives showed increased diatropic properties that were most pronounced for the palladium(II) complexes. These unique porphyrinoids provide further insights into the properties of benziporphyrins. 
    more » « less
  5. Isolable sulfonium-ylide stabilized palladium carbene complexes were synthesized through palladium(II)-induced cyclization of 1,2-alkynylarylsulfanes. X-ray crystallographic analysis characterized the maintenance of a palladium +2 oxidation state, with carbene-carbon–palladium bond lengths of 1.95 Å, indicating partial double bond character. These endocyclic sulfonium ylide carbenes represent the first characterized and/or isolable examples of this ligand class; such groups were previously proposed as reaction intermediates during cyclization–carbonylation reactions. A variety of palladium(II) complexes bearing sulfonium ylide carbene ligands, with differing substituents, were synthesized and the structure and stability of these complexes in solution were analyzed by 1H and 13C NMR spectroscopy, revealing reversibility and a stability dependence on substituents. The chirality of the sulfur heteroatom and the overall properties these ligands provide a potential electronic and steric alternative to existing carbene ligands, which could facilitate the future development of complementary metal-based reactivity. 
    more » « less