Asymmetric Synthesis of O‐Acetylcyanohydrins by Reaction of Aldehydeswith NaCN/KCN Catalyzed by Recyclable Chiral DimericTitanium(IV)/Vanadium(V) Salen Complexes

Abstract

The efficient catalytic asymmetric addition of an inexpensive and nonvolatile cyanide source such as NaCN or KCN and acetic anhydride to various aldehydes was catalyzed by recyclable dimeric Ti IV and V V chiral salen complexes at -20°C. High chiral induction (96 % ee) in the O-acetylcyanohydrin was obtained in the case of 2-fluorobenzaldehyde, and the results achieved with sodium cyanide are quite comparable

Dimeric & Polymeric Chiral Schiff Base Complexes and Supported BINOL Complexes as Potential Recyclable Catalysts in Asymmetric Kinetic Resolution and C–C Bond Formation Reactions

“…The polymeric catalyst 39 was found to be more reactive than the monomeric catalyst 41 to produce chiral ethyl cyanohydrincarbonate in high optical purity ( Complex 37 Fig. 15 Cyanide addition to carbonyl compound using dimeric salen complexes [137] HT/basic alumina used in this study were recoverable and recyclable several times with the retention of its performance [142].…”

“…Besides, V(V) salen complex turned out to be the most efficient recyclable system reported so far in the literature and is relatively better than the monomeric Ti(IV) salen system. Both the catalysts were recovered after first use and recycled four times effectively [137]. asymmetric O-acetyl cyanation of various aldehydes with KCN as an inexpensive and non-volatile cyanide source and acetic anhydride at -20°C (Fig.…”

Recyclable Stereoselective Catalysts

“…Furthermore, catalysts 79 and 80 (Fig. 1.35 ) were recovered by precipitation (with hexane) and reused up to four cycles with consistent enantioselectivity [150] .…”

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

“…Earlier, we have reported solvent-free and environmentally benign synthetic protocols for the synthesis of cyanosilylethers [56], aminonitriles [57] and b-amino ketone (Mannich reaction) [58]. In this context and our ongoing interest in cyanation of aldehydes [59][60][61][62][63][64], the present study describes the addition of ethylcyanoformate to aldehydes using commercially available N,N-dimethylpyridin-4-amine (DMAP) as a catalyst to give ethylcyanocarbonates in excellent yields under solvent-free conditions at room temperature in short period of time.…”