Regio‐controllable Cobalt‐Catalyzed Sequential Hydrosilylation/Hydroboration of Arylacetylenes

Abstract

Regiodivergent addition reactions provides traightforwarda nd atom-economic approaches to access different regioisomers.H owever,t he regio-chemistry control to access all the possible results is still challenging especially for the reaction involving multiple addition steps.Herein, we reported regio-controllable cobalt-catalyzed sequential hydrosilylation/ hydroboration of arylacetylenes,d elivering all the possible regio-outcomes with high regioselectivities (up to > 20/1 rr for all the cases). Each regioisomer of value-added silylboronates could be efficiently and regioselectively obtained from the same materials.T he adjustment of the ligands of cobalt catalysts combined with dual catalysis relays trategy is the key to achieve regio-chemistry control. This regio-controllable researchmight inspire the exploration of the diversity-oriented synthesis that involves multiple additions and provide full sets of regioisomers of other synthetic useful molecules.Scheme 1. Metal-catalyzed sequential hydrosilylation/hydroboration of arylacetylenes.

Pd/NHC-Controlled Regiodivergent Defluorinative Allylation of gem-Difluorocyclopropanes with Allylboronates

“…However, developing regiodivergent reactions with transition-metal catalysts is challenging because it can be very difficult to energetically distinguish between structurally similar transition states leading to a pair of regioisomers. One of the most reliable and promising approaches for steering regioselectivity in transition-metal catalysis is through varying the ancillary ligand, which has the most direct impact on the steric and electronic environment around the metal center . Traditionally, ligand screening for transition-metal catalysis relies on trial and error and generates an undesirable amount of waste.…”

The transition metal-catalysed hydroboration reaction

“…Asymmetric cobalt-catalysed hydroborations of 1-aryl-1-silyl alkenes have drawn interest as the second part of a hydrosilylation/hydroboration sequence, starting with the hydrosilylation of a terminal alkyne. 289–292 Substrates that are bulkier 99 or more electron-poor 278 than 2-phenylpropene also showed increased selectivity for the linear hydroboration product in rhodium-catalysed reactions. The copper catalysed hydroboration of a 1-phenyl-1-borylalkene gave the tertiary diborylated product (Scheme 51).…”

Photocatalyzed Regioselective Hydrosilylation for the Divergent Synthesis of Geminal and Vicinal Borosilanes

“…The synthesis of borosilanes, mainly through transition-metal catalysis, has attracted much attention in the last decade (Fig. 1a) [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . For instance, Morken and co-workers reported the synthesis of geminal borosilanes through Pt-catalyzed hydrosilylation of β-alkyl-substituted alkenyl boronates 8 .…”