Palladium(II)-Catalyzed Reaction of Lawsones and Propargyl Carbonates: Construction of 2,3-Furanonaphthoquinones and Evaluation as Potential Indoleamine 2,3-Dioxygenase Inhibitors
An efficient reaction utilizing propargyl carbonates through Claisen rearrangement to synthesize furanonaphthoquinones is described. The remarkable transformation exhibits excellent functional group tolerance, affording the target furanonaphthoquinones in moderate to good yields (41–85%) undermildreactionconditions. Scaled-up preparation of the model product can make this reaction a method of choice
supported homogeneouscatalyst. The heterogenised catalyst and its homogeneous counterpart exhibited similar activity in a range of enyne cyclisation reactions. Bearing in mind that π–π interactions are affected by temperature and solvent polarity, the reuse and robustness of the supported homogeneouscatalyst was tested to explore the scope and limitations of the recyclability of this catalyst. Under
Ru being served? The reactions of propargylic carbonates with silyl diazo compounds in the presence of [Cp*RuCl(cod)] as a catalyst precursor led to the formation of dienyl carbonates in excellent yields under mild conditions (see scheme; Y=SiMe3).
茹被送达?在作为催化剂前体的[Cp * RuCl(cod)]存在下,炔丙基碳酸酯与甲硅烷基重氮化合物的反应导致在温和条件下以优异的收率形成碳酸二烯酯(参见方案; Y = SiMe 3)。
Gold-catalyzed rearrangement of propargylic tert-butyl carbonates
作者:Andrea K. Buzas、Florin M. Istrate、Fabien Gagosz
DOI:10.1016/j.tet.2008.11.108
日期:2009.2
Diversely substituted 4-alkylidene-1,3-dioxolan-2-ones are efficiently synthesized by a gold(I)-catalyzed rearrangement of propargylic tert-butyl carbonates. The substrates are readily accessible and the transformation, which is performed under mild reaction conditions using a low loading of catalyst, allows the synthesis of cyclic carbonates, which would be less efficiently obtained using traditional methods. This procedure has also been applied to the stereoselective synthesis of (E)- or (Z)-4-halomethylene-1,3-dioxolan-2-ones, which Proved to be suitable substrates for palladium-catalyzed cross-coupling reactions. (C) 2008 Elsevier Ltd. All rights reserved.
Hg(OTf)2-Catalyzed cyclization of alkynyl tert-butylcarbonate leading to cyclic enol carbonate
Mercuric triflate was shown to be a powerful catalyst for the cyclization of alkynyl tert-butylcarbonates giving rise to cyclic enol carbonates under mild conditions. Internal alkynyl carbonate affords endo cyclization product selectively, while terminal alkynyl carbonate provides only exo cyclization product. (c) 2006 Elsevier Ltd. All rights reserved.