Water Control over the Chemoselectivity of a Ti/Ni Multimetallic System: Heck- or Reductive-Type Cyclization Reactions of Alkyl Iodides
摘要:
A versatile Ti/Ni multimetallic protocol is described for the efficient catalysis of two different reactions, namely a Heck- and reductive-type cyclization of alkyl iodides, in the absence or presence of water, respectively. Noteworthy, the versatility of Ti(III) chemistry allows an oxidative ending step under reductive conditions to give Heck-type products, and the good H-atom transfer capabilities of Ti(III)-aqua complexes ensure reductive-type cyclizations.
Palladium-Catalyzed Carbocyclizations of Unactivated Alkyl Bromides with Alkenes Involving Auto-tandem Catalysis
作者:Alexander R. O. Venning、Megan R. Kwiatkowski、Joan E. Roque Peña、Brendan C. Lainhart、Akil A. Guruparan、Erik J. Alexanian
DOI:10.1021/jacs.7b06794
日期:2017.8.23
carbocyclization of unactivated alkyl bromides with alkenes is described. This approach uses a commercially available bisphosphine ligand and avoids the use of carbon monoxide atmosphere present in prior studies involving alkyl iodides. Detailed mechanistic studies of the transformation are performed, which are consistent with auto-tandem catalysis involving atom-transfer radical cyclization followed by catalytic
Nickel‐Catalyzed Mizoroki–Heck‐Type Reactions of Unactivated Alkyl Bromides
作者:Megan R. Kwiatkowski、Erik J. Alexanian
DOI:10.1002/anie.201810757
日期:2018.12.17
The development of a general, nickel-catalyzed alkyl-Mizoroki-Heck reaction of unactivated alkylbromides is described. The mild reaction proceeds efficiently using a wide range of primary and secondary alkylbromides, and examples of intermolecular cross-couplings are provided. Reaction alkene regioselectivity is significantly enhanced over prior carbocyclizations using palladium catalysis. Mechanistic
Vitamin B<sub>12</sub> and a metal–organic framework enable the photocatalytic generation of alkyl radicals
作者:Krzysztof R. Dworakowski、Artur Chołuj、Michał J. Chmielewski、Dorota Gryko
DOI:10.1039/d3cc02941g
日期:——
A versatile Co-catalyst-vitamin B12 (cobalamin)-can be photochemically reduced to its catalytically active Co(I) form under visible light irradiation, in the presence of MIL-125-NH2(Ti) as a photocatalyst and utilized for the generation of alkylradicals. The prior reduction of cobalamin to the Co(II) form is not required in this method.
一种多功能助催化剂 - 维生素 B 12 (钴胺素) - 在 MIL-125-NH 2 (Ti) 作为光催化剂的情况下,在可见光照射下可以光化学还原为其催化活性 Co( I ) 形式,并用于烷基自由基的产生。该方法不需要预先将钴胺素还原成Co( II )形式。
Water Control over the Chemoselectivity of a Ti/Ni Multimetallic System: Heck- or Reductive-Type Cyclization Reactions of Alkyl Iodides
作者:Alba Millán、Luis Álvarez de Cienfuegos、Delia Miguel、Araceli G. Campaña、Juan M. Cuerva
DOI:10.1021/ol3028913
日期:2012.12.7
A versatile Ti/Ni multimetallic protocol is described for the efficient catalysis of two different reactions, namely a Heck- and reductive-type cyclization of alkyl iodides, in the absence or presence of water, respectively. Noteworthy, the versatility of Ti(III) chemistry allows an oxidative ending step under reductive conditions to give Heck-type products, and the good H-atom transfer capabilities of Ti(III)-aqua complexes ensure reductive-type cyclizations.