A mild, simple, novel, and highly efficient method for the rapid protection of various primary, secondary, tertiary aliphatic alcohols, aromatic alcohols, and oximes using hexamethyldisilazane (HMDS) in the presence of silica-supported sodium hydrogen sulfate (NaHSO 4 -SiO 2 ), as an active, inexpensive, nontoxic, heterogeneous, and readily available catalyst under ambient conditions is described.
Alumina sulfuricacid as a recyclable catalyst conducts the transformation of various types of alcohol, phenols, and oximes with hexamethyldisilazane (HMDS) to the corresponding O-trimethylsilylated compounds in good to excellent yields under mild and ambient conditions with short reaction times. The method is highly selective for the conversion of primary alcohols in the presence of secondary and
B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Catalyzed Hydrogenation of Oxime Ethers without Cleavage of the NO Bond
作者:Jens Mohr、Martin Oestreich
DOI:10.1002/anie.201407324
日期:2014.11.24
The hydrogenation of oximes and oxime ethers is usually hampered by NO bond cleavage, hence affording amines rather than hydroxylamines. The boron Lewis acid B(C6F5)3 is found to catalyze the chemoselective hydrogenation of oxime ethers at elevated or even room temperature under 100 bar dihydrogen pressure. The use of the triisopropylsilyl group as a protecting group allows for facile liberation of
肟和肟醚的氢化通常受到NO键断裂的阻碍,因此提供的是胺而不是羟胺。发现硼路易斯酸B(C 6 F 5)3在升高的或什至在室温下在100巴的二氢压力下催化肟醚的化学选择性氢化。使用三异丙基甲硅烷基作为保护基可以容易地释放出游离的羟胺。
Cobalt(III)-Catalyzed CH/NO Functionalizations: Isohypsic Access to Isoquinolines
CH/NOfunctionalizations by cobalt(III) catalysis allowed the expedient synthesis of a broad range of isoquinolines. Thus, internal and challenging terminal alkynes proved to be viable substrates for an isohypsic annulation, which was shown to proceed by a facile CH cobaltation.
Ç H /Ñ ö官能化由钴(III)催化使范围广泛的异喹啉的的适宜的合成。因此,内部和具有挑战性的末端炔烃被证明是一个isohypsic环,其通过示出一个浅显下进行可行的基板 ħcobaltation。