Lewis Bases as Catalysts in the Reduction of Imines and Ketones with Silanes (n?→?σ ^* )

Evaluation of 3,3′-Triazolyl Biisoquinoline N,N′-Dioxide Catalysts for Asymmetric Hydrosilylation of Hydrazones with Trichlorosilane

“…Trichlorosilane reversibly forms a hypervalent silicon complex with Lewis-bases that is believed to be the active reducing species. Since Matsumura's seminal work, that employed N-formylproline-derived catalysts [33,34], and the milestone achieved by Malkov and Kočovský with their N-methyl-L -valine-based catalysts [35][36][37], numerous chiral Lewis-base catalysts have been reported for the asymmetric hydrosilylation of ketimines with trichlorosilane (selected reviews; [30][31][32], selected references; [38][39][40][41][42][43][44][45]). While the majority of these catalysts are amide-based Lewis-bases, other kinds of Lewis-bases are also reported, which includes pyridine N-oxides (selected references; [46][47][48][49][50][51]), phosphine oxides (selected references; [52][53][54]), and sulfinamides (selected references; [55,56]).…”

“…Herein describes our preliminary investigations in this area. Among the reported reducing agents that are amenable for organocatalysis (selected reviews; [27][28][29]), trichlorosilane is particularly attractive because it is a readily available, inexpensive and easy-to-handle liquid (selected reviews; [30][31][32]). Furthermore, it only produces innoxious NaCl and SiO2 as by-products upon quenching with aqueous NaOH or NaHCO3 solutions, which are easily separable from the reaction products (i.e., organic compounds).…”

Steps toward Rationalization of the Enantiomeric Excess of the Sakurai–Hosomi–Denmark Allylation Catalyzed by Biisoquinoline N,N’-Dioxides Using Computations

“…In particular, the Sakurai-Hosomi-Denmark allylation reaction (Scheme 1) is commonly used for the development of new chiral Lewis bases. Significant experimental contributions in this field include the work of Denmark, Kočovský, Malkov, Nakajima, and more recently from one of us [4][5][6][7][8][9][10][11]. The stereochemical aspects of these reactions have been initially rationalized using conventional stereoelectronic arguments for the transition states (TSs) of the transient hypervalent silicon intermediates [12].…”

“…Computational work from Wheeler, [13][14][15][16] has elucidated that the interaction between the ligands in these TSs play a central role for the enantioselectivity of a reaction. Specifically, a C2-symmetric bidentate Lewis base, RSiCl3, and an electrophile Significant experimental contributions in this field include the work of Denmark, Kočovský, Malkov, Nakajima, and more recently from one of us [4][5][6][7][8][9][10][11]. The stereochemical aspects of these reactions have been initially rationalized using conventional stereoelectronic arguments for the transition states (TSs) of the transient hypervalent silicon intermediates [12].…”

An Easy Approach to Obtain Alcohol-Amines by Reduction of Alcohol Functionalized Imines

“…In fact, it is one of the central reactions in organic chemistry, and the search for more efficient and practical synthetic methods for carrying out this reduction is a theme of constant interest [3][4][5]. Many reduction agents have been tested in order to produce the mentioned transformation, and H2 [6], silanes [7,8], boranes [9], and borohydrides [10] are maybe the most popular ones. Among them, sodium borohydride is commonly chosen to reduced polydentate Schiff bases to amines, because it is cheap and its excess is easily destroyed by an acid medium [11,12].…”