POLÁŠEK, Jan, Jan PACIOREK, Jakub STOŠEK, Hugo SEMRÁD, Markéta MUNZAROVÁ a Ctibor MAZAL. Stereoselective Bromoboration of Acetylene with Boron Tribromide: Preparation and Cross-Coupling Reactions of (Z)-Bromovinylboronates. The Journal of Organic Chemistry. Washington, D.C.: American Chemical Society, 2020, roč. 85, č. 11, s. 6992-7000. ISSN 0022-3263. Dostupné z: https://dx.doi.org/10.1021/acs.joc.0c00341. |
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@article{1658581, author = {Polášek, Jan and Paciorek, Jan and Stošek, Jakub and Semrád, Hugo and Munzarová, Markéta and Mazal, Ctibor}, article_location = {Washington, D.C.}, article_number = {11}, doi = {http://dx.doi.org/10.1021/acs.joc.0c00341}, keywords = {HALOBORATION REACTIONS; UNSATURATED-COMPOUNDS; BUILDING-BLOCKS; HYDROBORATION; ISOMERIZATION; CYCLIZATION; CATALYST; ALKYNES; ROUTE}, language = {eng}, issn = {0022-3263}, journal = {The Journal of Organic Chemistry}, title = {Stereoselective Bromoboration of Acetylene with Boron Tribromide: Preparation and Cross-Coupling Reactions of (Z)-Bromovinylboronates}, url = {https://pubs.acs.org/doi/10.1021/acs.joc.0c00341}, volume = {85}, year = {2020} }
TY - JOUR ID - 1658581 AU - Polášek, Jan - Paciorek, Jan - Stošek, Jakub - Semrád, Hugo - Munzarová, Markéta - Mazal, Ctibor PY - 2020 TI - Stereoselective Bromoboration of Acetylene with Boron Tribromide: Preparation and Cross-Coupling Reactions of (Z)-Bromovinylboronates JF - The Journal of Organic Chemistry VL - 85 IS - 11 SP - 6992-7000 EP - 6992-7000 PB - American Chemical Society SN - 00223263 KW - HALOBORATION REACTIONS KW - UNSATURATED-COMPOUNDS KW - BUILDING-BLOCKS KW - HYDROBORATION KW - ISOMERIZATION KW - CYCLIZATION KW - CATALYST KW - ALKYNES KW - ROUTE UR - https://pubs.acs.org/doi/10.1021/acs.joc.0c00341 L2 - https://pubs.acs.org/doi/10.1021/acs.joc.0c00341 N2 - The mechanism of acetylene bromoboration in neat boron tribromide was studied carefully by means of experiment and theory. Besides the syn-addition mechanism through a four-center transition state, radical and polar anti-addition mechanisms are postulated, both triggered by HBr, which is evidenced also to take part in the Z/E isomerization of the product. The proposed mechanism is well supported by ab initio calculations at the MP2/6-31+G* level with Ahlrichs’ SVP all-electron basis for Br. Implicit solvation in CH2Cl2 has been included using the PCM and/or SMD continuum solvent models. Comparative case studies have been performed involving the B3LYP/6-31+G* with Ahlrichs’ SVP for Br and MP2/Def2TZVPP levels. The mechanistic studies resulted in development of a procedure for stereoselective bromoboration of acetylene yielding E/Z mixtures of dibromo(bromovinyl)borane with the Z-isomer as a major product (up to 85%). Transformation to the corresponding pinacol and neopentyl glycol boronates and stereoselective decomposition of their E-isomer provided pure (Z)-(2-bromovinyl)boronates in 57–60% overall yield. Their reactivity in a Negishi cross-coupling reaction was tested. An example of the one-pot reaction sequence of Negishi and Suzuki–Miyaura cross-couplings for synthesis of combretastatin A4 is also presented. ER -
POLÁŠEK, Jan, Jan PACIOREK, Jakub STOŠEK, Hugo SEMRÁD, Markéta MUNZAROVÁ a Ctibor MAZAL. Stereoselective Bromoboration of Acetylene with Boron Tribromide: Preparation and Cross-Coupling Reactions of (Z)-Bromovinylboronates. \textit{The Journal of Organic Chemistry}. Washington, D.C.: American Chemical Society, 2020, roč.~85, č.~11, s.~6992-7000. ISSN~0022-3263. Dostupné z: https://dx.doi.org/10.1021/acs.joc.0c00341.
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