Alkylation of the Inverted Porphyrin Nickel(II) Complex by Dihalogenalkanes:  Formation of Monomeric and Dimeric Derivatives

• Published in: Journal of organic chemistry Vol. 67; no. 25; pp. 8917 - 8927
• Main Authors: Schmidt, Izabela, Chmielewski, Piotr J, Ciunik, Zbigniew
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13-12-2002
• Subjects: Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Organic chemistry; Preparations and properties; Nickel II; NMR spectrometry; X ray diffraction; Alkylation; Isomer; Reactivity; Basic medium; Aromatic compound; Dimer; Metalloporphyrin; Chemical synthesis; Mass spectrometry; Ethylenic compound; Halogen Organic compounds
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo026328n

An efficient and simple method of modification of “inverted” porphyrin is provided by reactions of 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrinatonickel(II) 2 with dihalogenalkanes under basic conditions. The substituents are bound to the internal carbon or external nitrogen of the inverted pyrrole depending on dihalogenalkane and basic catalyst. The monomeric 2- or 21-ethoxymethyl-substituted species are formed in the reaction of 2 with dihalomethanes and sodium ethoxide or ethanol in the presence of K2CO3. A novel, dimeric 21,21‘-ethylene-linked derivative 11 is obtained from 2 and ethylene bromide in dichloromethane in the presence of potassium carbonate end ethanol, while application of potassium tert-butoxide promotes formation of N-bromoethyl-substituted monomer 12. Reaction of 2 with propylene bromide in the presence of proton scavenger efficiently leads to the 21-allyl-substituted monomer 14 that is a product of the HBr elimination from a transient 21-bromopropyl-substituted species. The new compounds have been identified and characterized by means of mass spectrometry and optical and NMR spectroscopies. A single-crystal X-ray analysis performed for 12 allows discussion of structural parameters concerning the macrocycle and coordination core. Formation of deprotonated species [2]-, which is proposed as a key intermediate in the alkylation reaction, has been observed spectroscopically. Chirality of the N-substituted derivatives induced by protonation of the internal carbon is observed by NMR at low temperatures.