29536-29-6Relevant articles and documents
H-BPin/KOtBu Promoted Activation of Cobalt Salt to a Heterotopic Catalyst for Highly Selective Cyclotrimerization of Alkynes
Song, Shuo,Li, Chuhan,Liu, Tianfen,Zhang, Panke,Wang, Xiaoming
supporting information, p. 6925 - 6930 (2021/09/14)
A mixture of HBPin with KOtBu was found to activate cobalt salt to form a heterotopic cobalt species that is highly active for catalytic intermolecular trimerization of alkynes. This protocol affords 1,2,4-regioisomers in good yields with high regioselectivities under mild conditions. These salient features, together with the operational simplicity and high efficiency, as well as obviating the use of any costly and/or air sensitive ligands, renders the protocol promising for practical applications.
1,3,5-Trialkyl-2,4,6-triiodobenzenes: Novel x-ray contrast agents for gastrointestinal imaging
Estep, Kimberly G.,Josef, Kurt A.,Bacon, Edward R.,Illig, Carl R.,Toner, John L.,Mishra, Dinesh,Blazak, William F.,Miller, Dennis M.,Johnson, David K.,Allen, Jack M.,Spencer, Andy,Wilson, Susan A.
, p. 1940 - 1948 (2007/10/03)
Examination of the gastrointestinal (GI) tract has been performed for decades using barium sulfate. Although this agent has many recognized limitations including extreme radiopacity, poor intrinsic affinity for the GI mucosa, and very high density, no alternative contrast agents have emerged which produce comparable or better contrast visualization. In fact, the various techniques of the GI radiologic examination (i.e., single contrast, double contrast, biphasic) were developed to compensate for its limitations. Each of these techniques requires complex patient manipulation to achieve adequate mucosal coating or compression to overcome the marked radiopacity of barium sulfate in order to obtain a diagnostically useful examination. A series of novel radiopaque oils, the 1,3,5-trialkyl-2,4,6-triiodobenzenes, was designed to improve the efficacy, stability, and safety of barium formulations. These substances were prepared in two steps from 1,3,5- trichlorobenzene. Compound 17 (1,3,5-tri-n-hexyl-2,4,6-triiodobenzene), formulated as an oil-in-water emulsion, was found to be well-tolerated in rodents (mice, hamsters, rats) following acute oral and/or intraperitoneal administrations at 4 times the anticipated human clinical dose. No metabolism of 17 was detected in rat, hamster, dog, monkey, or human hepatic microsomes, suggesting the lack of oral toxicity was a consequence of poor absorption. In imaging experiments in dogs, emulsions of 17 have demonstrated excellent mucosal coating and improved radiodensity relative to barium sulfate suspensions. On the basis of the preliminary imaging and toxicity data, compound 17 was selected as a potential development candidate.
Regiospecific Synthesis of Aromatic Compounds via Organometallic Intermediates. 3. n-Alkyl-Substituted Benzene
Eapen, Kalathil C.,Dua, Sujan S.,Tamborski, Christ
, p. 478 - 482 (2007/10/02)
High molecular weight tri- and tetra-n-alkylbenzenes have been synthesized by the cross-coupling of the appropriate chlorinated benzenes with long-chain n-alkylmagnesium bromides using (1,2-bis(diphenylphosphino)ethane)nickel(II)chloride as catalyst.The reactions proceeded without any positional scrambling or alkyl group isomerization.A new method is described for the preferential substitution of one chlorine atom by an n-alkyl group in 1,3,5-trichlorobenzene.The reaction between an n-alkylmagnesium bromide and 1,3,5-trichlorobenzene catalyzed by Nickelacetylacetonate at low temperature and in tetrahydrofuran solvent favors monosubstitution.The cross-coupling reactions of these n-alkyldichlorobenzenes with other n-alkylmagnesium bromides, in the presence of NiCl2(dppe), proceeded at a much slower rate than those of 1,3,5-trichlorobenzene to yield the asymmetric 1,3,5-tri-n-alkylbenzenes.
