Solvent/Oxidant-Switchable Synthesis of Multisubstituted Quinazolines and Benzimidazoles via Metal-Free Selective Oxidative Annulation of Arylamidines
摘要:
A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.
Manganese(I)-Catalyzed Transfer Hydrogenation and Acceptorless Dehydrogenative Condensation: Promotional Influence of the Uncoordinated N-Heterocycle
作者:Chong Zhang、Bowen Hu、Dafa Chen、Haiping Xia
DOI:10.1021/acs.organomet.9b00475
日期:2019.8.26
showed the highest activity. The reactions proceeded well with 0.5 mol % of catalyst loading and 20 mol % of t-BuOK at 85 °C for 24 h. Furthermore, 3 was also used as a catalyst for the synthesis of primary alcohols via transfer hydrogenation of aldehydes and the synthesis of 1,2-disubstituted benzimidazoles and quinolines via acceptorless dehydrogenative condensations.
四种二齿锰(I)配合物[(C 5 H 4 N-C 5 H 3 N-OH)Mn(CO)3 Br](1),[(C 9 H 6 N-C 5 H 3 N-OH)Mn(CO )3 Br](2),[(C 8 H 5 N 2 -C 5 H 3 N-OH)Mn(CO)3 Br](3)和[(C 8 H 5 N 2 -C 5 H 3 N-OCH 3)Mn(CO)3Br](4)被合成。测试了这些配合物作为酮转移氢化的催化剂,其中3种显示出最高的活性。在85℃下,在0.5mol%的催化剂负载量和20mol%的t- BuOK下,反应进行得很好,持续了24小时。此外,3还用作催化剂,用于通过醛的转移氢化合成伯醇,以及通过无受体的脱氢缩合反应合成1,2-二取代的苯并咪唑和喹啉。
Air-stable Ruthenium(II)-NNN Pincer Complexes for the Efficient Coupling of Aromatic Diamines and Alcohols to 1<i>H</i>
-benzo[<i>d</i>
]imidazoles with the Liberation of H<sub>2</sub>
Two new phosphine‐free RuII‐NNN pincer complexes ([RuCl(L1)(CH3CN)2]Cl (1) and [RuCl(L2)(CH3CN)2]Cl (2) [L1=2,6‐bis(1H‐imidazole‐2‐yl)pyridine, L2=2,6‐bis(1‐hexyl‐1H‐imidazole‐2‐yl)pyridine] were synthesized to catalyze the condensation of benzyl alcohol and benzene‐1,2‐diamine homogeneously to 2‐pheny‐1H‐benzo[d]imidazole and H2. The reactivity in the order of 1>2 is lower than that of the phosphine‐containing
Nickel catalyzed sustainable synthesis of benzazoles and purines <i>via</i> acceptorless dehydrogenative coupling and borrowing hydrogen approach
作者:Gargi Chakraborty、Rakesh Mondal、Amit Kumar Guin、Nanda D. Paul
DOI:10.1039/d1ob01154e
日期:——
benzoxazole via acceptorless dehydrogenative functionalization of alcohols. Using a bench stable, easy to prepare, and inexpensive Ni(II)-catalyst, [Ni(MeTAA)] (1a), featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)), a wide variety of polysubstituted benzimidazole, purine, benzothiazole, and benzoxazole derivatives were prepared via dehydrogenative coupling of alcohols with
Pd-Catalyzed Dehydrogenative Oxidation of Alcohols to Functionalized Molecules
作者:Takamichi Mori、Chihiro Ishii、Masanari Kimura
DOI:10.1021/acs.oprd.9b00207
日期:2019.8.16
A dehydrogenative oxidation reaction of primary alcohols to aldehydes catalyzed by a simple Pd/Xantphos catalytic system was developed under an argon or nitrogen atmosphere without oxidizing agents or hydrogen acceptors. The reaction product could be easily changed: under aerobic conditions, esters were obtained in aprotic solvents, whereas the corresponding carboxylic acids were produced in aqueous