1088-00-2Relevant articles and documents
Bridged [2.2.1] bicyclic phosphine oxide facilitates catalytic γ-umpolung addition-Wittig olefination
Zhang, Kui,Cai, Lingchao,Yang, Zhongyue,Houk,Kwon, Ohyun
, p. 1867 - 1872 (2018)
A novel bridged [2.2.1] bicyclic phosphine oxide, devised to circumvent the waste generation and burdens of purification that are typical of reactions driven by the generation of phosphine oxides, has been prepared in three steps from commercially availab
Phosphorescent OLEDs assembled using Os(ii) phosphors and a bipolar host material consisting of both carbazole and dibenzophosphole oxide
Lin, Cheng-Huei,Hsu, Che-Wei,Liao, Jia-Ling,Cheng, Yi-Ming,Chi, Yun,Lin, Tsung-Yi,Chung, Min-Wen,Chou, Pi-Tai,Lee, Gene-Hsiang,Chang, Chih-Hao,Shih, Chin-Yao,Ho, Chi-Lung
, p. 10684 - 10694 (2012)
We report on the synthesis of a new series of Os(ii) complexes (1-3) functionalized with 2-pyridyl (or 2-isoquinolyl) pyrazole chelates, together with a new diphosphine, 1,2-bis(phospholano)benzene chelate (pp2b). The resulting Os(ii) complexes are fully characterized and their structural versus spectroscopic properties have been comprehended by absorption/emission together with computational approaches. The inherent electron richness, restricted rotational barrier and good steric hindrance of pp2b lead to the production of both orange and red phosphorescence with high quantum efficiency. For exploring these Os(ii) based OLEDs, we also synthesized a bipolar material 5-[4-(carbazo-9-yl)phenyl] dibenzophosphole-5-oxide (CzPhO), possessing both carbazole donor and dibenzophosphole oxide acceptor. Successful fabrication of OLEDs using complexes 1 and 3 as the dopant and either 4,4′-N,N′- dicarbazolebiphenyl (CBP) or CzPhO as host is reported. For comparison, the CBP and CzPhO devices with 1 as the emitter showed peak efficiencies EQE of 10.9%, ηL of 21.7 cd A-1, and ηp of 11.9 lm W-1, and EQE of 14.3%, ηL of 34.8 cd A-1, and ηp of 45.2 lm W-1, respectively. The Royal Society of Chemistry 2012.
Biphilic Organophosphorus-Catalyzed Intramolecular Csp2-H Amination: Evidence for a Nitrenoid in Catalytic Cadogan Cyclizations
Nykaza, Trevor V.,Ramirez, Antonio,Harrison, Tyler S.,Luzung, Michael R.,Radosevich, Alexander T.
supporting information, p. 3103 - 3113 (2018/03/08)
A small-ring phosphacycloalkane (1,2,2,3,4,4-hexamethylphosphetane, 3) catalyzes intramolecular C-N bond forming heterocyclization of o-nitrobiaryl and -styrenyl derivatives in the presence of a hydrosilane terminal reductant. The method provides scalable access to diverse carbazole and indole compounds under operationally trivial homogeneous organocatalytic conditions, as demonstrated by 17 examples conducted on 1 g scale. In situ NMR reaction monitoring studies support a mechanism involving catalytic PIII/PV=O cycling, where tricoordinate phosphorus compound 3 represents the catalytic resting state. For the catalytic conversion of o-nitrobiphenyl to carbazole, the kinetic reaction order was determined for phosphetane catalyst 3 (first order), substrate (first order), and phenylsilane (zeroth order). For differentially 5-substituted 2-nitrobiphenyls, the transformation is accelerated by electron-withdrawing substituents (Hammett factor ? = +1.5), consistent with the accrual of negative charge on the nitro substrate in the rate-determining step. DFT modeling of the turnover-limiting deoxygenation event implicates a rate-determining (3 + 1) cheletropic addition between the phosphetane catalyst 3 and 2-nitrobiphenyl substrate to form an unobserved pentacoordinate spiro-bicyclic dioxazaphosphetane, which decomposes via (2 + 2) cycloreversion giving 1 equiv of phosphetane P-oxide 3·[O] and 2-nitrosobiphenyl. Experimental and computational investigations into the C-N bond forming event suggest the involvement of an oxazaphosphirane (2 + 1) adduct between 3 and 2-nitrosobiphenyl, which evolves through loss of phosphetane P-oxide 3·[O] to give the observed carbazole product via C-H insertion in a nitrene-like fashion.
Palladium-Catalyzed Synthesis of Six-Membered Benzofuzed Phosphacycles via Carbon-Phosphorus Bond Cleavage
Baba, Katsuaki,Tobisu, Mamoru,Chatani, Naoto
, p. 70 - 73 (2015/07/28)
The palladium-catalyzed synthesis of dibenzofused six-membered phosphacycles via carbon-phosphorus bond cleavage is developed. This method is compatible with a range of functional groups, such as esters, amides, and carbamates, which is in sharp contrast to the limitations of the classical method using organolithium reagents. (Figure Presented).