Diazaphosphinyl radical-catalyzed deoxygenation of α-carboxy ketones: a new protocol for chemo-selective C–O bond scission <i>via</i> mechanism regulation
作者:Jingjing Zhang、Jin-Dong Yang、Jin-Pei Cheng
DOI:10.1039/d0sc03220d
日期:——
diazaphosphinane based on a mechanism switch strategy. This new reaction features high efficiency, low cost and good group-tolerance, and is also amenable to catalytic deprotection of desyl-protected carboxylic acids and amino acids. Mechanistic studies indicated an electron-transfer-initiated radical process, underlining two crucial steps: (1) the initiator azodiisobutyronitrile switches originally hydridic
Two consecutive N-heterocyclic carbene (NHC) catalytic systems were combined in a one-pot cascade reaction for the assembly of aromatic aldehydes and 2-haloenals into a structurally complex γ-lactone backbone.
Résumé A facile synthesis of trisubstituted imidazoles containing furan rings was reported. Imidazoles were produced from 1,2-di(furan-2-yl)-2-oxoethyl carboxylates over solid alumina as solid support impregnated with ammonium acetate under solvent-free microwave-assisted conditions. The method possessed many remarkable advantages, such as the short reaction time (5–10 min), affording moderate to excellent yields and saving resources, conveniently operating process, which provided an attractive and environmentally-friendly approach for the synthesis of the important heterocyclic compounds. Moreover, the chemiluminescence property of some compounds synthesized has been investigated. Supplementary Materials: Supplementary material for this article is supplied as a separate file: mmc1.doc
Desyl and Phenacyl as Versatile, Photocatalytically Cleavable Protecting Groups: A Classic Approach in a Different (Visible) Light
作者:Elisabeth Speckmeier、Kirsten Zeitler
DOI:10.1021/acscatal.7b02117
日期:2017.10.6
carboxylic acids and amino acids, offering orthogonality to a great variety of other common protectinggroups. We further demonstrate the general applicability and versatility of these formerly underrated protectinggroups in combination with our catalytic cleavage conditions, as underscored by the gained high functional group tolerance. Moreover, this method could successfully be adapted to the requirements
已经开发了使用可见光光氧化还原催化来脱保护经典苯甲酰基(Pac)和去甲酰基(Dsy)保护基的高效催化策略。故意使用具有K 3 PO 4的中性两相乙腈/水混合物,并施加催化量的[Ru(bpy)3 ](PF 6)2与抗坏血酸结合使用是对Pac和Dsy保护的羧酸进行真正的催化脱保护的关键。我们温和而稳健的方案允许以非常好的定量产量快速而选择性地释放游离羧酸,而只需要低的催化剂负载量(1 mol%)。从市场上可买到的前体容易引入的Pac和Dsy均可用于直接保护羧酸和氨基酸,与许多其他常见的保护基团具有正交性。我们进一步证明了这些先前被低估的保护基团与我们的催化裂解条件相结合的普遍适用性和多功能性,这是由获得的高官能团耐受性所强调的。而且,该方法可以成功地适应固相合成的要求。作为有效可见光,光催化连接子裂解的原理证明,将Boc保护的三肽从市售的溴化王树脂中分离出来。