1,2-Diarylethanols by Alternative Regioselective Reductive Ring-Opening of 2,3-Diaryloxiranes
作者:Nadia Di Blasio、Maria Teresa Lopardo、Paolo Lupattelli
DOI:10.1002/ejoc.200800992
日期:2009.2
Non-symmetrical trans-2,3-diaryloxiranes have been regioselectively opened by catalytic hydrogenation over Pd/C, NaBH4/Pd and [Cp2TiCl]/H2O. Although in the catalytic hydrogenation reactions the epoxides were mainly opened at the β-carbon with respect to the substituted aryl ring in all cases, with the [Cp2TiCl]/H2O system the regioselectivity was affected by the electronic properties of the aryl residues
Highly efficient asymmetric bioreduction of 1-aryl-2-(azaaryl)ethanones. Chemoenzymatic synthesis of lanicemine
作者:Ramón Liz、Elisa Liardo、Francisca Rebolledo
DOI:10.1039/c9ob01616c
日期:——
1-Aryl-2-(azaaryl)ethanols with ee > 99% have been prepared by KRED-catalyzed reduction of the ketone precursors. A chemoenzymatic synthesis of lanicemine is described.
Silver catalyzed zinc Barbier reaction of benzylic halides in water
作者:Lothar W. Bieber、Elisabeth C. Storch、Ivani Malvestiti、Margarete F. da Silva
DOI:10.1016/s0040-4039(98)02199-6
日期:1998.12
Benzylic chlorides react in aqueous dibasic potassium phosphate under silver catalysis with aromatic aldehydes in the presence of zinc dust to give 1,2-diaryl alcohols in moderate to good yields. Dimerization to bibenzyls and reduction of the halide are important side reactions. A wide range of substituted aromatic and heteroaromatic aldehydes and of substituted benzylic chlorides can be used. Aliphatic
Cation sensors containing a (bpy)Re(CO)3 group linked to an azacrown ether via an alkenyl or alkynyl spacer: synthesis, characterisation, and complexation with metal cations in solution
作者:Jared D. Lewis、John N. Moore
DOI:10.1039/b401092b
日期:——
alkali-metal (Li+, Na+ and K+) or alkaline-earth metal (Mg2+, Ca2+ and Ba2+) cations to the azacrown; the magnitude of the blue shift is dependent on the cation, with protonation giving the largest shift of ca. 100 nm. Cationbinding constants in the range of log K = 1–4 depend strongly on the identity of the metal cation. Protonation or cation complexation causes downfield shifts in the 1H NMR resonances from
两个[(bpy)Re(CO)3 L] +络合物(py = 2,2'-联吡啶),其中L含有连接到重新氮杂-15-冠-5醚经由一个烯基-或炔基-吡啶间隔基已与模型配合物一起合成。复杂的解决方案乙腈 已经通过UV-Vis吸收进行了研究 光谱学,然后按一维和 2D 1 H NMR 光谱学。强的紫外可见 分配给L内配体内电荷转移跃迁的谱带 配体,蓝色转变为氮杂皇冠的质子化 氮原子或与碱金属(Li +,Na +和K +)或碱土金属(Mg 2 +,Ca 2+和Ba 2+)络合阳离子到阿扎克朗 蓝移的幅度取决于阳离子,质子化使ca的变化最大。100纳米阳离子log K = 1-4范围内的结合常数在很大程度上取决于金属的身份阳离子。质子化或阳离子络合导致大多数氮杂冠和L的1 H NMR共振中的下场偏移配体 质子,其大小与UV-Vis波段的蓝移相关;氮杂皇冠的位移1 H NMR共振报告了不同金属如何阳离子 与
STEREO- AND REGIO-SELECTIVE ALDOL-TYPE REACTIONS OF ALKYLPYRIDINES WITH BENZALDEHYDE
作者:Hiroshi Hamana、Tsutomu Sugasawa
DOI:10.1246/cl.1984.1591
日期:1984.9.5
Stereo- and regio-selectivity in the reaction of alkylpyridines with benzaldehyde were studied. Erythro-selectivity could be obtained in the reaction of 2-alkylpyridine with benzaldehyde in the presence of dialkylboryl triflate and triethylamine. Substitution at the 2- or 4-position of 2,4-lutidine could be controlled by the combination of dialkylboryl triflate and an aliphatic tertiary amine. The steric effect had an important role in the reaction of 4-picoline and lepidine.