A colourful azulene-based protecting group for carboxylic acids
作者:Thomas W. Bevan、James Francis-Taylor、Helena Wong、Peter T. Northcote、Joanne E. Harvey
DOI:10.1016/j.tet.2018.04.066
日期:2018.6
An intensely blue-coloured protecting group for carboxylicacids has been developed. The protecting group is introduced through a Steglich esterification that couples 6-(2-hydroxyethyl)azulene (AzulE) and the carboxylicacid substrate. Deprotection is effected under basic conditions by the addition of the amidine base DBU, whereupon cleavage occurs, accompanied by a colour change. A two-step deprotection
A new method for the mild radical hydrosilylation of alkenes and alkynes is described. Silylated cyclohexadienes that can be readily prepared on large scale are used as radical hydrosilylating reagents. Non-activated alkenes and alkynes are hydrosilylated in high yields. The reaction can be combined with CC bond formation, as demonstrated for the preparation of silylated cycloalkanes from the corresponding
描述了烯烃和炔烃的温和自由基氢化硅烷化的新方法。可以容易地大规模制备的甲硅烷基化环己二烯被用作自由基氢化硅烷化试剂。非活化烯烃和炔烃以高产率氢化硅烷化。该反应可以与 CC 键的形成相结合,如从相应的二烯制备甲硅烷基化环烷烃所证明的那样。此外,自由基氢化硅烷化与β-断裂反应相结合用于合成烯丙基硅烷和醛和酮的氢化硅烷化提供受保护的醇可以很容易地通过该策略进行。
Undesirable deprotection of O-TBDMS groups by Pd/C-catalyzed hydrogenation and chemoselective hydrogenation using a Pd/C(en) catalyst
作者:Kazuyuki Hattori、Hironao Sajiki、Kosaku Hirota
DOI:10.1016/s0040-4020(01)00060-6
日期:2001.3
In general, O-TBDMS protective groups have been believed to be stable toward Pd/C-catalyzed hydrogenation conditions. In practice, however, frequent and unexpected loss of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. When a 10% Pd/C-ethylenediamine complex catalyst [10% Pd/C(en)] was used instead of 10% Pd/C, the undesirable problem was perfectly overcome and the chemoselective hydrogenation of reducible functionalities leaving intact the TBDMS protective group was achieved. (C) 2001 Elsevier Science Ltd. All rights reserved.
The undesirable lability of tert-butyldimethylsilyl ethers under Pd/C-catalyzed hydrogenation conditions and solution of the problem by using a Pd/C(en) catalyst
作者:Kazuyuki Hattori、Hironao Sajiki、Kosaku Hirota
DOI:10.1016/s0040-4039(00)00935-7
日期:2000.7
While the frequent and unexpected loss of the TBDMS protective group of a variety of hydroxylic functions was demonstrated under neutral and mild hydrogenation conditions using 10% Pd/C, the undesirable problem was perfectly overcome by using a 10% Pd/C-ethylenediamine complex catalyst. (C) 2000 Elsevier Science Ltd. All rights reserved.
Catalysis by Solid Superacids; 19<sup>1</sup>. Simplified and Improved Polymeric Perfluorinated Resin Sulfonic Acid (Nafion-H) Catalyzed Protection-Deprotection Reactions