23810-08-4Relevant academic research and scientific papers
Rh-Catalyzed Regioselective Dialkylation of Cage B-H bonds in o-Carboranes: Oxidative Heck Reactions via an Enol Isomerization
Wang, Qian,Tian, Song,Zhang, Chuyi,Li, Jiangwei,Wang, Zhixuan,Du, Yongmei,Zhou, Ling,Lu, Jian
supporting information, p. 8018 - 8021 (2019/10/19)
In the presence of a carboxylic acid directing group, Rh-catalyzed regioselective directed dialkylation of B(4,5)-H bonds in o-carboranes and oxidative coupling with allylic alcohols is reported. This strategy constructs a series of 4,5-dialkylated o-carboranes in good yields with excellent regioselectivity. A possible catalytic cycle is proposed that involves a tandem sequence of Rh-catalyzed cage B-H activation, alkene insertion, selective β-H elimination, enol isomerization, and decarboxylation.
The synthesis and molecular and crystal structures of 1-methyl-2-carboxy-1, 2-dicarba-closo-dodecaborane(12), 1-phenyl-2-carboxy-1,2-dicarba-closo- dodecaborane(12) and 1-phenyl-2-benzoyl-1,2-dicarba-closo-dodecaborane(12)
Venkatasubramanian, Ulaganathan,Donohoe, David J.,Ellis, David,Giles, Barry T.,MacGregor, Stuart A.,Robertson, Susan,Rosair, Georgina M.,Welch, Alan J.,Batsanov, Andrei S.,Boyd, Lynn A.,Copley, Royston C.B.,Fox, Mark A.,Howard, Judith A.K.,Wade, Kenneth
, p. 629 - 636 (2008/10/09)
The structures of 1-Me-2-COOH-1,2-closo-C2B10H 10 (1), 1-Ph-2-COOH-1,2-closo-C2B10H 10 (2) and 1-Ph-2-COPh-1,2-closo-C2B10H 10 (3) have been determined by X-ray crystallography. In 1 the orientation of the COOH group is defined by θCOOH=65.0(2) syn°, and this group H-bonds to that in a second molecule via a centrosymmetric eight-membered ring, R22(8). DFT calculations on the parent species 1-COOH-1,2-closo-C2B 10H11 reveal that the structure with θ COOH=90syn°is preferred, with a barrier to COOH rotation of ≈17 kJmol-1. Similar calculations on 1 yield a lower rotational barrier, ≈7 kJmol-1, because internal H-bonding is now denied. In compound 2 the COOH group is twisted to lower θ values [5.0(3)°and 39.7(3)°] but both crystallographically independent molecules exist as dimers in the solid state by virtue of R2 2(8) rings. Compound 2 crystallises from wet solvent as a monohydrate, the structure of which reveals a non-planar centrosymmetric R 44(12) ring and near-orthogonal Ph and COOH substituents [θPh=6.7(2) and θCOOH=78.0(2) syn°]. In compound 3 molecular association by H-bonding is blocked, so 3 serves as a useful comparative structure for 2.
Study of the transmetallation of silicon derivatives of o-carboranes on treatment with BunLi
Zakharkin,Ol'shevskaya,Guseva,Shemyakin
, p. 475 - 477 (2007/10/03)
Silyl-substituted o-carboranes 1-R-2-Me3Si(CH2)n-1,2-C2B 10H10 (R = Me, Ph; n = 0, 1) undergo transmetallation on treatment with BunLi to form lithium derivatives of o-carboranes, 1-R-2-Li(CH2)n-1,2-C2B10H 10, where n = 0, 1. A silicon derivative of o-carborane, 1-Ph-2-(Me3SiCHPh)-1,2-C2B10H10, undergoes neither transmetallation nor metallation at the benzyl CH-group on treatment with BunLi due to significant steric hindrance.
