Enantiospecific Synthesis of <i>ortho</i>-Substituted Benzylic Boronic Esters by a 1,2-Metalate Rearrangement/1,3-Borotropic Shift Sequence
作者:Stefan Aichhorn、Raphael Bigler、Eddie L. Myers、Varinder K. Aggarwal
DOI:10.1021/jacs.7b05880
日期:2017.7.19
ortho-substituted benzylic boronic esters with formal 1,1′-benzylidene insertion into the C–B bond. The reaction occurs by a SN2′ elimination and 1,2-metalate rearrangement of the N-activated boronate complex to afford a dearomatized intermediate, which undergoes a Lewis-acid catalyzed 1,3-borotropic shift to afford the boronic ester products in high yield and with excellent enantiospecificity. The use of
已经研究了苄胺和硼酸酯之间的偶联反应。邻-Lithiated苄胺与硼酸酯反应,并且一个Ñ -activator,得到邻位与正规1,1'-亚苄基取代的插入苄硼酸酯到C-B键。该反应通过S N 2'的消除和N活化的硼酸酯络合物的1,2-金属化物重排而得到脱芳香化的中间体,该中间体经过路易斯酸催化的1,3-硼向转变以得到硼酸酯产物。高收率和优异的对映体特异性。使用富含对映体的α-取代的苄胺得到相应的具有高ee的仲硼酸酯。
Stereodivergent Olefination of Enantioenriched Boronic Esters
作者:Roly J. Armstrong、Cristina García‐Ruiz、Eddie L. Myers、Varinder K. Aggarwal
DOI:10.1002/anie.201610387
日期:2017.1.16
A stereodivergent coupling reaction between vinyl halides and boronicesters is described. This coupling process proceeds without a transition-metal catalyst, instead proceeding by electrophilic selenation or iodination of a vinyl boronate complex followed by stereospecific syn or anti elimination. Chiral, nonracemic boronicesters could be coupled with complete enantiospecificity. The process enables
Enantiospecific Trifluoromethyl-Radical-Induced Three-Component Coupling of Boronic Esters with Furans
作者:Yahui Wang、Adam Noble、Christopher Sandford、Varinder K. Aggarwal
DOI:10.1002/anie.201611058
日期:2017.2.6
2-lithio furan and non-racemic secondary and tertiary alkyl or aryl boronic esters undergo deborylative three-component coupling to give the corresponding 2,5-disubstituted furans with excellent levels of enantiospecificity. The process proceeds via the reaction of boronate complexes with a trifluoromethyl radical, which triggers 1,2-metallate rearrangement upon single-electron oxidation. Alternative
<i>ortho</i>
-Directing Chromium Arene Complexes as Efficient Mediators for Enantiospecific C(sp<sup>2</sup>
)-C(sp<sup>3</sup>
) Cross-Coupling Reactions
作者:Raphael Bigler、Varinder K. Aggarwal
DOI:10.1002/anie.201711816
日期:2018.1.22
ortho‐lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho‐selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X‐ray, NMR, and IR experiments to elucidate the reaction mechanism.
Enantiospecific sp2–sp3 coupling of secondary and tertiary boronic esters
作者:Amadeu Bonet、Marcin Odachowski、Daniele Leonori、Stephanie Essafi、Varinder K. Aggarwal
DOI:10.1038/nchem.1971
日期:2014.7
cross-coupling of boronic acids and related derivatives with sp2 electrophiles (the Suzuki–Miyaura reaction) is one of the most powerful C–C bond formation reactions in synthesis, with applications that span pharmaceuticals, agrochemicals and high-tech materials. Despite the breadth of its utility, the scope of this Nobel prize-winning reaction is rather limited when applied to aliphaticboronic esters. Primary