174808-86-7Relevant academic research and scientific papers
True metal-catalyzed hydroboration with titanium
He, Xiaoming,Hartwig, John F.
, p. 1696 - 1702 (1996)
Dicarbonyltitanocene is an efficient and highly selective catalyst for alkyne hydroborations by catecholborane and dimethyltitanocene is an efficient and highly selective catalyst for alkene hydroborations. These results contrast the hydroboration chemistry with other early transition metal complexes that simply lead to decomposition of catecholborane to form diborane and parallel the hydroboration chemistry of permethylcyclopentadienyl lanthanide complexes. Titanocene dicarbonyl leads to exclusive anti-Markovnikov regiochemistry and to exclusive single additions of catecholborane across alkynes. Dimethyltitanocene leads to predominantly anti-Markovnikov regiochemistry with alkyl-substituted olefins, and exclusive anti-Markovnikov regiochemistry with vinylarenes. Two titanium(III) complexes, Cp2Ti(H2Bcat) and Cp2Ti(Bcat2), were isolated from the reaction mixtures. These Ti(III) complexes, as well as [Cp2TiH]2 and [Cp2TiMe]2, catalyze the addition of catecholborane to olefins more slowly than the titanium(II) and titanium(IV) compounds. These results are rationalized by a σ bond metathsis between catecholborane and titanocene alkene and alkyne complexes that possess metallacyclopropane and metallacyclopropene character as the B-C bond-forming step. This B-C bond-forming step of the catalysis was observed directly in model reactions.
Hydroboration of Alkenes Catalysed by a Nickel N-Heterocyclic Carbene Complex: Reaction and Mechanistic Aspects
Chetcuti, Michael J.,Cornaton, Yann,Djukic, Jean-Pierre,Ritleng, Vincent,Ulm, Franck
, (2020/07/13)
The pentamethylcyclopentadienyl N-heterocyclic carbene nickel complex [Ni(η5-C5Me5)Cl(IMes)] (IMes=1,3-dimesitylimidazol-2-ylidene) efficiently catalyses the anti-Markovnikov hydroboration of alkenes with catecholborane in
P1 Phenethyl peptide boronic acid inhibitors of HCV NS3 protease
Priestley,De Lucca, Indawati,Ghavimi, Bahman,Erickson-Viitanen, Susan,Decicco, Carl P.
, p. 3199 - 3202 (2007/10/03)
A series of peptide boronic acids containing extended, hydrophobic P1 residues was prepared to probe the shallow, hydrophobic S1 region of HCV NS3 protease. The p-trifluoromethylphenethyl P1 substituent was identified as optimal with respect to inhibitor potency for NS3 and selectivity against elastase and chymotrypsin.
