Transition metal free catalytic hydroboration of aldehydes and aldimines by amidinato silane

Abstract

The transition metal free catalytic hydroboration of aldehydes and ketones is very limited and has not been reported with a well-defined silicon(iv) compound. Therefore, we chose to evaluate the previously reported silicon(iv) hydride [PhC(NtBu)SiHCl], (1) as a single component catalyst and found that it catalyzes the reductive hydroboration of a range of aldehydes with pinacolborane (HBpin) under ambient conditions. In addition, compound 1 can catalyze imine hydroboration. DFT calculation was carried out to understand the mechanism.

Catalytic Hydroboration of Organic Nitriles Promoted by Aluminum Complex

“…[9][10][11][12][13][14] As a result, innumerable procedures have been evolved to accomplish the addition of boranes to nitriles. All these procedures require more or less effective catalysts based on transition-metal complexes such as Co, Fe, Ru, [15][16][17][18][19][20][21][22][23] alkaline earth metal (Mg), [24][25][26][27][28][29][30][31][32][33][34][35] but the processes culminate in frustrated Lewis pairs. [36][37][38] On the other hand, while the reduction of aryl and alkyl nitriles can be achieved using stoichiometric quantities of maingroup reducing agents such as LiAlH 4 and NaBH 4 , [39] the combustible nature of these reagents and large quantities of inorganic waste by-products they generate render the process unattractive, and hence reductive hydroboration is preferable in order to provide further functionality to the resultant amine.…”

Sterically bulky amido magnesium methyl complexes: syntheses, structures and catalysis

“…14 When compared to the transition metal catalyzed hydroboration of aldehydes and ketones which has been extensively investigated, the research on the catalytic hydroboration of carbonyl compounds using main group catalysts is less developed but has recently received considerable attention by many research groups. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Compared to the precious and relatively toxic transition metals, amongst the main group metals, magnesium is earthabundant, non-toxic and inexpensive. The Mg-catalyzed hydroboration has been relatively well explored and has shown high reactivity in recent studies.…”

Catalyst‐Free and Solvent‐Free Facile Hydroboration of Imines

“…The corresponding secondary amines 8 a and 8 b having the nitro/nitrile group unaltered were exclusively obtained in moderate yields at ambient temperature which can be improved by conducting the reaction at higher temperature of 60 °C (Scheme ). It is worth to mention that the efficiency of our protocol is much higher when compared to previously reported Er, Ca, and Si‐based catalyst systems …”

“…Among metal catalyzed processes, transition metal and even rare earth metal complexes have been studied (Scheme ). There is also a recent surge in utilization of s ‐ and p ‐block elements and till date, several research groups have studied the hydroboration of carbonyl and to some extent imine compounds using main‐group element (Ca, Mg, Al,– Si) based systems (Scheme ). Alkali metal based compounds for example, n BuLi and NaOH have also been utilized for the same process .…”