191171-55-8Relevant articles and documents
Self-activation and 1,8-stereoinduction in a boronate-substituted dienophile
Kennedy, Jason W. J.,Hall, Dennis G.
, p. 477 - 479 (2002)
The [4+2] cycloaddition of ortho-boronoanilide dienophile 4 with cyclopentadiene was found to proceed faster than both its para isomer 8 and the unsubstituted derivative 6, thereby confirming that self-activation by internal coordination is operative in the case of 4. Chiral boronic esters derivatives 9 and 10 provided a small level of remote 1,8-stereoinduction. These results show that dialkoxyboronic esters can operate as weak, internal Lewis acids and activate carbonyl-containing functionalities in cycloaddition reactions.
1,3,5-Tris(2′-aminophenyl)benzene: A novel platform for molecular receptors
Pia?tek, Piotr,S?omiany, Norbert
, p. 2027 - 2030 (2006)
The synthesis of a novel, rigid, aromatic platform for molecular receptors is described. 1,3,5-Tris(2′-aminophenyl)benzene was prepared via Suzuki-Miyaura cross-coupling reactions of 2-aminophenylboronic acid with 1,3,5-triiodobenzene in the presence of Ba(OH)2, Pd(OAc)2 and (2-biphenyl)dicyclohexylphosphine. Alternatively, one-pot borylation of 2-bromoaniline and cross-coupling of the resulting boronate ester with 1,3,5-triiodobenzene was investigated. Georg Thieme Verlag Stuttgart.
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
Oxidation of Nonactivated Anilines to Generate N-Aryl Nitrenoids
Deng, Tianning,Mazumdar, Wrickban,Ford, Russell L.,Jana, Navendu,Izar, Ragda,Wink, Donald J.,Driver, Tom G.
supporting information, p. 4456 - 4463 (2020/03/05)
A low-temperature, protecting-group-free oxidation of 2-substituted anilines has been developed to generate an electrophilic N-aryl nitrenoid intermediate that can engage in C-NAr bond formation to construct functionalized N-heterocycles. The exposure of 2-substituted anilines to PIFA and trifluoroacetic acid or 10 mol percent Sc(OTf)3 triggers nitrenoid formation, followed by productive and selective C-NAr and C-C bond formation to yield spirocyclic- or bicyclic 3H-indoles or benzazepinones. Our experiments demonstrate the breadth of these oxidative processes, uncover underlying fundamental elements that control selectivity, and demonstrate how the distinct reactivity patterns embedded in N-aryl nitrenoid reactive intermediates can enable access to functionalized 3H-indoles or benzazepinones.