Synthesis of Isomerically Pure (<i>Z</i>)-Alkenes from Terminal Alkynes and Terminal Alkenes: Silver-Catalyzed Hydroalkylation of Alkynes
作者:Mitchell T. Lee、Madison B. Goodstein、Gojko Lalic
DOI:10.1021/jacs.9b09336
日期:2019.10.30
molecules and often are used as intermediates in organic synthesis. Many alkenes exist in two stereoisomeric forms (E and Z), which have different structures and different properties. The selective formation of the two isomers is an important synthetic goal that has long inspired the development of new synthetic methods. However, the efficient synthesis of diastereopure, thermodynamically less stable, Z-alkenes
Chemoselective thioacetalisation and transthioacetalisation of carbonyl compounds catalysed by tetrabutylammonium tribromide (TBATB)Dedicated to Professor Subramanian Ranganathan on the occasion of his 70th birthday.
作者:Sarala Naik、Rangam Gopinath、Mousumi Goswami、Bhisma K. Patel
DOI:10.1039/b402648a
日期:——
Thioacetals and thioketals of various aldehydes and ketones were obtained directly from carbonylcompounds or by a transthioacetalisation process from cyclic O,O-acetals in the presence of dithiols and a catalytic amount of tetrabutylammonium tribromide (TBATB). Chemoselective thioacetalisation of aromatic aldehydes containing an electron-donating group in the presence of an aldehyde containing an
Tetrabutylammonium Tribromide (TBATB) as An Efficient Generator of HBr for an Efficient Chemoselective Reagent for Acetalization of Carbonyl Compounds
作者:Rangam Gopinath、Sk. Jiaul Haque、Bhisma K. Patel
DOI:10.1021/jo025701o
日期:2002.8.1
Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions
作者:Apurba Sinhamahapatra、Narottom Sutradhar、Malay Ghosh、Hari C. Bajaj、Asit B. Panda
DOI:10.1016/j.apcata.2011.05.032
日期:2011.7
the presence of appreciable amount of Brönsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketalformation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from
报道了一种新颖,方便,一步合成的方法,该方法使用碳酸锆配合物合成中孔硫酸盐氧化锆(m-SZ),并将其用作固体酸催化剂,用于不同羰基化合物的缩醛化。通过在550°C下煅烧6小时除去表面活性剂(十六烷基甲基溴化铵,CTAB),可实现m-SZ的高BET比表面积(234 m 2 g -1)。显微镜分析表明存在带有蠕虫状孔的球形颗粒。吡啶吸附的m-SZ和NH 3的DRIFT(漫反射FTIR)-TPD(程序升温脱附)分析表明存在大量的布朗斯台德酸位。合成的m-SZ对通过缩醛/缩酮形成保护羰基化合物具有高催化活性。对于开环缩酮(来自环己酮和甲醇),在室温下于无溶剂条件下,在1小时内可获得97%的转化率和100%的选择性。从反应体系中分离出来的催化剂可以很容易地循环利用,而催化活性没有明显的损失。
Microwave-assisted Rapid Ketalization/Acetalization of Aromatic Aldehydes and Ketones in Aqueous Media
作者:Ali Pourjavadi、Bibi Fatemeh Mirjalili
DOI:10.1039/a902252j
日期:——
Aromaticaldehydes and ketones are readily acetalized or ketalized under microwave irradiation in the presence of water as a solvent.