| POLÁŠEK, Jan, Jan PACIOREK, Jakub STOŠEK, Hugo SEMRÁD, Markéta MUNZAROVÁ and 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, vol. 85, No 11, p. 6992-7000. ISSN 0022-3263. Available from: 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 and 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, vol.~85, No~11, p.~6992-7000. ISSN~0022-3263. Available from: https://dx.doi.org/10.1021/acs.joc.0c00341.
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