Metal catalyzed asymmetric cyanation reactions

Activation of trimethylsilyl cyanide by potassium phthalimide for facile synthesis of TMS-protected cyanohydrins

“…Because of their importance in the pharmaceutical, agrochemical and other industrial applications, a large body of work has been devoted to the development of cyanohydrin synthesis . However, Preparation of cyanohydrins by the addition of highly toxic HCN to carbonyl group is not a straightforward process and the procedure should be undertaken with caution [3,21]. The other problem which affects the yields of the products stems from the existence of inevitable equilibrium condition between the reactants and the adduct product [2,20].…”

“…First reported in 1832 by Winkler, this reaction is the foundation of the Kiliani-Fisher synthesis of carbohydrates [1][2][3]. Cyanohydrins are of synthetic interest as they can be elaborated into several significant building blocks such as a-hydroxy acids, a-amino acids, a-hydroxy aldehydes or ketones, vicinal diols, b-amino alcohols, etc.…”

“…The cyanosilylation of carbonyl compounds is particularly suitable since the silyl protecting groups can be removed under very mild reaction conditions. The cyanohydrin trimethylsilyl ethers are generally prepared by the addition of trimethylsilyl cyanide (TMSCN), a safe and easily handled reagent compared to HCN and KCN or NaCN [3][4][5][6]21,42], to carbonyl compounds in the presence of Lewis acids [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], inorganic Lewis bases [22][23][24][25], and double activating [3,26] or bifunctional catalytic systems [27][28][29]. However, many of these methods suffer from several disadvantages such as use of heavy and expensive metal catalysts [3,[12][13][14][15][16], high catalyst loading [6,13,14,22,23], the requirement for an inert atmosphere or anhydrous solvents [11][12][13]…”

N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions

“…Cyanohydrins are valuable intermediates for the synthesis of range of compounds viz., a-amino acids, a-hydroxy acids, b-amino alcohols, vicinal diols and a-hydroxy ketones [1][2][3][4][5] which are important building blocks for numerous pharmaceuticals, agrochemicals and insecticides [6][7][8][9][10][11][12][13]. Cyanohydrins are conventionally synthesized by the cyanation of carbonyl compounds using KCN, NaCN, trimethylsilyl cyanide (TMSCN) and HCN as sources of cyanide in the presence of various Lewis acid/base catalysts [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Enantioselective trimethylsilylcyanation of benzaldehyde using pyrrolidine-based chiral salen ligands

“…Titanium, vanadium and aluminium compounds have been successfully used as Lewis acids in these reactions and structurally diverse chiral ligands have proved efficient in this enantioselective process. [1][2][3][4][5][6] Oguni's pioneering work with Schiff bases [7][8][9] led to the development of many ligands of this type for the enantioselective trimethylsilylcyanation of aldehydes. [10][11][12][13][14][15][16] Our research interests have focused on enantioselective catalysis studies, namely transfer hydrogenation of alkenes, 17,18 alkylation of aldehydes with diethylzinc [19][20][21][22] and, more recently, on the trimethylsilylcyanation of aldehydes with trimethylsilyl cyanide.…”