Carbon-Based Leaving Group in Substitution Reactions: Functionalization of sp<sup>3</sup>-Hybridized Quaternary and Tertiary Benzylic Carbon Centers
作者:Stuart J. Mahoney、Tiantong Lou、Ganna Bondarenko、Eric Fillion
DOI:10.1021/ol301442z
日期:2012.7.6
Lewis acid promoted substitution reactions employing Meldrum’s acid and 5-methyl Meldrum’s acid as carbon-based leavinggroups are described which transform unstrained quaternary and tertiary benzylic Csp3–Csp3 bonds into Csp3–X bonds (X = C, H, N). Importantly, this reaction has a broad scope in terms of both suitable substrates and nucleophiles with good to excellent yields obtained (typically >90%)
Chiral iridium complexes ligated by anionic oxazoline-bearing NCP-type pincer ligands were developed and applied to the asymmetric transfer hydrogenation (ATH) of diarylethenes using environmentally benign ethanol as the hydrogen donor. High enantioselectivities could be achieved for substrates bearing ortho-Me, ortho-Cl, or ortho-Br substituents on one of the aryl groups. The ATH of ortho-Br-substituted
开发了由带有阴离子恶唑啉的 NCP 型钳形配体连接的手性铱配合物,并将其应用于使用环境友好型乙醇作为氢供体的二芳基乙烯的不对称转移氢化 (ATH)。对于在芳基之一上带有邻-Me、邻-Cl或邻-Br取代基的底物可以实现高对映选择性。由于 C (芳基) -Br 键易于经历各种新的键形成事件,邻位-Br 取代的二芳基乙烯的 ATH特别有吸引力。
Stereospecific Nickel-Catalyzed Cross-Coupling Reactions of Benzylic Ethers with Isotopically-Labeled Grignard Reagents
作者:David D. Dawson、Elizabeth R. Jarvo
DOI:10.1021/acs.oprd.5b00148
日期:2015.10.16
we highlight the potential of stereospecific nickel-catalyzed cross-couplingreactions for applications in the pharmaceutical industry. Using an inexpensive and sustainable nickel catalyst, we report a gram-scale Kumada cross-couplingreaction. Reactions are highlystereospecific and proceed with inversion at the benzylic position. We also expand the scope of our reaction to incorporate isotopically
Novel phenstatin analogues with a 2-naphthyl moiety combined with either a 2,3,4- or a 3,4,5-trimethoxyphenyl ring have been synthesized, and their tubulin polymerization inhibiting and cytotoxic activities have been evaluated. The 2-naphthyl ring is a better replacement for the 3-hydroxy-4-methoxyphenyl ring in the phenstatin series than in the combretastatin series. For the naphthylphenstatins, the carbonyl is required, and the preferred orientation of the trimethoxyphenyl ring is the one found in combretastatins. (c) 2007 Elsevier Ltd. All rights reserved.
Naphthylphenstatins as tubulin ligands: Synthesis and biological evaluation
A new family of naphthalenic analogues of phenstatins with modi. cations on the ketone-bridge has been synthesised. The synthesised compounds have been assayed for tubulin polymerisation inhibitory activity as well as for cytotoxic activity against cancer cell lines. The naphthalene has been confirmed as a good surrogate for the isovanillin moiety (3-hydroxy-4-methoxyphenyl) of phenstatin, when combined with the 3,4,5-trimethoxyphenyl ring, but not when combines with the 2,3,4-trimethoxyphenyl ring. Binding models for the synthesised compounds have been generated and analysed in terms of a pharmacophore proposed for colchicine site ligands. The ketone is the optimal bridge substitution but E-acetyloximes or acetylhydrazones are also tolerated. Significant differences with indole substituted phenstatins are observed and discussed. (C) 2008 Published by Elsevier Ltd.