First Microwave-Assisted Catalytic Wittig Reaction
作者:Thomas Werner、Marcel Hoffmann、Sunetra Deshmukh
DOI:10.1002/ejoc.201403113
日期:2014.11
introduce a novel catalyticWittigreaction based on an inexpensive and readily available phosphane oxide as a precatalyst. The performance of the reaction under microwave irradiation led to significantly improved yields and reaction rates relative to those obtained under conventional heating. Moreover, herein we enclose the first example of the asymmetric catalyticWittigreaction based on a chiral
Scope and Limitation of the Microwave-Assisted Catalytic Wittig Reaction
作者:Marcel Hoffmann、Sunetra Deshmukh、Thomas Werner
DOI:10.1002/ejoc.201500310
日期:2015.7
We have developed a microwave-assisted catalyticWittigreaction. In this paper, we give full account of the scope and limitations of this reaction. A screening of various commercially available phosphine oxides as precatalysts revealed Bu3P=O to be the most promising candidate. We tested 10 silanes for the in situ reduction of the phosphine oxide to generate Bu3P as the actual catalyst. Different
我们开发了一种微波辅助催化 Wittig 反应。在本文中,我们充分考虑了该反应的范围和局限性。对各种市售氧化膦作为预催化剂的筛选表明,Bu3P=O 是最有希望的候选者。我们测试了 10 种硅烷原位还原氧化膦以生成 Bu3P 作为实际催化剂。测试不同的环氧化物作为掩蔽碱。在这方面,环己烯氧化物和丁烯氧化物被证明是合适的。该反应可在 125 °C 下进行,但在 150 °C 下可获得更高的产率和 E/Z 选择性。在优化的反应条件下,报道了各种醛类转化为相应烯烃的40多个实例。以高达 88% 的产率获得了具有高 E 选择性的产物。
Studies in the oxidative ring-opening of catechols and o-benzoquinones. Lead tetraacetate versus the copper(I) chloride/pyridine/methanol system
作者:James G Walsh、Patrick J Furlong、Louise A Byrne、Declan G Gilheany
DOI:10.1016/s0040-4020(99)00651-1
日期:1999.9
Lead tetraacetate oxidative ring-opening of a series of substituted catechols provides the corresponding substituted cis,cis-2,4-diene-1,6-dioates (1–10) in fair to good yields. A number of improvements on Wiessler's procedure for this reaction are reported. The analogous copper(I) chloride/pyridine/methanol ring-opening was found to be ineffective as a general synthetic method for this transformation