Consecutive β,β′‐Selective C(sp³)−H Silylation of Tertiary Amines with Dihydrosilanes Catalyzed by B(C₆F₅)₃

Abstract

Tris(pentafluorophenyl)borane has been found to catalyze the twofold C(sp 3)ÀH silylation of various trialkylamine derivatives with dihydrosilanes, furnishing the corresponding 4-silapiperidines in decent yields. The multi-step reaction cascade involves amine-to-enamine dehydrogenation at two alkyl residues and two electrophilic silylation reactions of those enamines, one inter-and one intramolecular.

Synthetic Approaches for the Construction of Five- and Six-Membered Silaazacycles

“…In 2021, Oestreich and co-workers developed a B(C 6 F 5 ) 3catalyzed ,′-selective Csp 3 -H silylation of acyclic tertiary amines 107 with dihydrosilanes to furnish the 1,4azasilinanes 108 (Scheme 29). 40 The reaction showcased the first accomplishment of the challenging twofold Csp 3 -H silylation. The reaction tolerated various tertiary amines bearing two ethyl groups or those other than ethyl.…”

Recent Advances in Catalysis Using Organoborane-Mediated Hydride Abstraction

“…In 2021, Oestreich and co-workers reported a B(C6F5)3-catalyzed β,β'-H silylation of tertiary amines 72, yielding sila analogues of piperidines 74 (Scheme 9). 25 Scheme 9 Borane-mediated hydride abstraction leads to the β,β'-H silylation of tertiary Amines for the synthesis of sila-piperidines.…”

Nickel‐Catalyzed Cross‐Redistribution between Hydrosilanes and Silacyclobutanes

“…[5] There are several difficulties to overcome to achieve high cross redistribution selectivity: 1) how to decrease selfredistribution, [5,[12][13][14][15] 2) how to avoid the dehydrogenative side reactions, [16][17][18][19] 3) how to avoid the subsequent reactions of the newly formed SiÀ H bond (Figure 1a)? [20][21][22][23][24][25] A handful of examples in selective cross-redistribution of silanes have been achieved by using the entropy-driven/LeChatelier's principle-controlled strategy, that is, the reaction equilibrium is shifted to the product side through the generation of highly volatile silane by-products, such as SiH 4 , MeSiH 3 , or Me 2 SiH 2 (Figure 1b). [12][13][14][15] Seminal work are Hou and coworkers' Lewis acid-catalyzed selective cross-redistribution of hydrosilanes [12] and Chen and co-workers' ytterbiumcatalyzed hydrosilane cross-redistribution.…”