Solvent-modulated Pd/C-catalyzed deprotection of silyl ethers and chemoselective hydrogenation
摘要:
Recently we have reported undesirable and frequent deprotection of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. The deprotection of silyl ethers is susceptible to significant solvent effect. TBDMS and TES protecting groups were selectively cleaved in the presence of acid-sensitive functional groups such as TIPS ether, TBDPS ether and dimethyl acetal under hydrogenation condition using 10% Pd/C in MeOH. In contrast, chemoselective hydrogenation of reducible functional groups such as acetylene, olefin and benzyl ether, proceeds in the presence of TBDMS or TES ethers in AcOEt or MeCN. (C) 2004 Elsevier Ltd. All rights reserved.
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‐Hydroboration of Propargyl Alcohol Derivatives and Related Substrates
作者:Lauren E. Longobardi、Alois Fürstner
DOI:10.1002/chem.201902228
日期:2019.8
in good to excellent levels of regio‐ as well as stereoselectivity, provided that the triple bond bears one linear and one singly‐branched substituent. In such cases, the reaction follows an unusual trans‐addition mode and places the boron entity distal to the branching point. The resulting alkenyl boronates, which are difficult to make otherwise, can be engaged in numerous enabling downstream processes
Rapid Assembly of Structurally Defined and Highly Functionalized Conjugated Dienes via Tethered Enyne Metathesis
作者:Qingwei Yao
DOI:10.1021/ol016026s
日期:2001.6.1
[reaction: see text] Conjugated dienes are versatile building blocks in organic synthesis, and the development of new methods for their synthesis remains an important topic in modern synthetic organic chemistry. We describe here an expedient synthesis of highly functionalized conjugated dienes through sequential silicon-tethered ring-closingenynemetathesis mediated by Grubbs' Ru carbene catalysts
A direct and convenient approach for the coupling of propargylic substrates with diphenylphosphine oxide in the presence of Tf2O and 2,6-lutidine has been developed. The method provides a general approach for the construction of attractive allenylphosphoryl skeletons with high atom and step economy under metal free conditions.
Complex α-Pyrones Synthesized by a Gold-Catalyzed Coupling Reaction