Biomedical subjects
Publications and source records attributed to MM Haley.
High-temperature intramolecular cyclization of N, N-dialkyl-N'-(4-substituted-2-ethynylphenyl)triazenes provides under neutral conditions both 6-substituted cinnolines and 5-substituted isoindazoles in moderate to excellent yields.
Graphdiyne (1) is a member of a novel family of interesting and potentially important allotropes of carbon. Reported herein are the synthesis and spectroscopic characterization of model substructures 2-6. The macrocycles were prepared by the intramolecular cyclization of suitable alpha,omega-polyynes. Key to the success of this approach was the development of an in situ protiodesilylation/alkynylation reaction utilizing reactive phenylbutadiyne synthons. This new method has allowed for the preparation of the largest, most complete substructures of the graphdiyne network to date (3-6).
This Letter describes the synthesis of the first macrobicyclic subunits of the hypothetical all-carbon network graphyne. Key to synthetic success is an intramolecular Sonogashira cross-coupling sequence.
Several 1,2-diphenyl-3-alkynylcyclopropenes were prepared by the reaction of acetylenic nucleophiles with diphenylcyclopropenylium perchlorate. The cyclopropenes were converted into alkynylcyclopropenylium salts via hydride abstraction with triphenylmethyl cation. Attempts to prepare a dication from either ethyne-bridged or butadiyne-bridged biscyclopropenes produced only the corresponding monocations. A dication was prepared when an ethylene spacer was inserted between the acetylene groups of the butadiyne-bridged biscyclopropene. Single-crystal X-ray structures of three of the cyclopropenylium ions were obtained. pK(R+) titrations were carried out on two of the salts, which showed that acetylene substituents provide about the same degree of stability to the cyclopropenylium core as a phenyl group. Nucleophilic addition to the alkynylcyclopropenylium ions under kinetic conditions gave a statistical mixture of products; however, under thermodynamic reaction conditions, nucleophilic addition followed by ring opening produced only one of three possible products. Calculations at the ab initio level were carried out to determine the charge distribution of the cations.
Metal- halogen exchange of vinylcyclopropene 4 followed by addition of [(Me3P)2Ir(CO)Cl] produced iridabenzvalene 5. The metallabenzene valence isomer was characterized by NMR and IR spectroscopy and by X-ray crystallography. Isomerization of complex 5 to iridabenzene derivatives 6 and 13 was accomplished by thermolysis and by Ag+ ions, respectively. The former transformation was a clean and quantitative process that displayed first-order kinetics.