Abstract
Alkenyl boronic esters are important reagents in organic synthesis. Herein, we report that these valuable products can be accessed by the homologation of boronic esters with a lithiated epoxysilane. Aliphatic and electron-rich aromatic boronic esters provided vinylidene boronic esters in moderate to high yields, while electron-deficient aromatic and vinyl boronic esters were found to give the corresponding vinyl silane products. Through DFT calculations, this divergence in mechanistic pathway has been rationalized by considering the stabilization of negative charge in the transition state of the elimination step. This vinylidene homologation was used in a short six step stereoselective synthesis of the proposed structure of machillene, however, synthetic and reported data were found to be inconsistent.
| Original language | English |
|---|---|
| Journal | Angewandte Chemie-International Edition |
| Early online date | 31 Jul 2019 |
| DOIs | |
| Publication status | E-pub ahead of print - 31 Jul 2019 |
Cite this
Vinylidene Homologation of Boronic Esters and its Application to the Synthesis of the Proposed Structure of Machillene. / Fordham, James M; Grayson, Matthew N; Aggarwal, Varinder Kumar.
In: Angewandte Chemie-International Edition, 31.07.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Vinylidene Homologation of Boronic Esters and its Application to the Synthesis of the Proposed Structure of Machillene
AU - Fordham, James M
AU - Grayson, Matthew N
AU - Aggarwal, Varinder Kumar
N1 - © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2019/7/31
Y1 - 2019/7/31
N2 - Alkenyl boronic esters are important reagents in organic synthesis. Herein, we report that these valuable products can be accessed by the homologation of boronic esters with a lithiated epoxysilane. Aliphatic and electron-rich aromatic boronic esters provided vinylidene boronic esters in moderate to high yields, while electron-deficient aromatic and vinyl boronic esters were found to give the corresponding vinyl silane products. Through DFT calculations, this divergence in mechanistic pathway has been rationalized by considering the stabilization of negative charge in the transition state of the elimination step. This vinylidene homologation was used in a short six step stereoselective synthesis of the proposed structure of machillene, however, synthetic and reported data were found to be inconsistent.
AB - Alkenyl boronic esters are important reagents in organic synthesis. Herein, we report that these valuable products can be accessed by the homologation of boronic esters with a lithiated epoxysilane. Aliphatic and electron-rich aromatic boronic esters provided vinylidene boronic esters in moderate to high yields, while electron-deficient aromatic and vinyl boronic esters were found to give the corresponding vinyl silane products. Through DFT calculations, this divergence in mechanistic pathway has been rationalized by considering the stabilization of negative charge in the transition state of the elimination step. This vinylidene homologation was used in a short six step stereoselective synthesis of the proposed structure of machillene, however, synthetic and reported data were found to be inconsistent.
U2 - 10.1002/anie.201907617
DO - 10.1002/anie.201907617
M3 - Article
JO - Angewandte Chemie-International Edition
JF - Angewandte Chemie-International Edition
SN - 1433-7851
ER -