Asymmetric addition of hydrogen cyanide to alkenes catalyzed by a zerovalent palladium compound

Abstract

The addition of hydrogen cyanide t o alkenes in high yields and with significant amounts (ca. 30%) of asymmetric induction has been achieved when transition metal catalysts with chiral ligands are used. Many asymmetric hydrogenation reactions have been reported,' but in contrast, few examples have been published in which new carbon-carbon bonds have been formed. Two examples where significant asymmetric induction has been achieved are in reactions of norbornene with other akenes2 and in catalytic allylic alkylation~.~ Reaction of hydrogen cyanide with norbornene using a palladium catalyst that we formulate as [( + )-DIOPIPdt gave 2-exocyanonorbornane, [ . I D + 3.4", in which the (lS, 2S, 4R)-(+)enantiomer predominated (SCHEME 1). This was demonstrated by hydrolysis to the corresponding carboxylic acid which had [ . I D + 3.0". The pure (lS, 2s. 4R)enantiomer has [a]D + 10.7"; and thus the optical induction was 28%. SCHEME 1When reactions were carried out with a deficiency of hydrogen cyanide (32 mmol) versus norbornene (64 mmol) in benzene at 130°C in the presence of [( + ) -DIOPIPd (0.09 mmol), the yield of 2-exocyanonorbornane was 40%. This yield increased to 80% when a small amount of free (+ )-DIOP (0.025 mmol) was added. Reaction with this amount of (+ )-DIOP but at a lower temperature, 80T, gave a lower yield (40%) but a slight increase in optical induction (31 %). Reaction Supported by the Australian Research Grants Committee. t DIOP, ~3-O-Isopropylidene-2,3dihydroxy-I.4-bis(diphenylphosphino)butane. 225 WnJ!T23/%0/0333-0225 SO1.75/1@ 1980. NYAS

Binaphthol‐Based Diphosphite Ligands in Asymmetric Nickel‐Catalyzed Hydrocyanation of Styrene and 1,3‐Cyclohexadiene: Influence of Steric Properties

“…All preparations were carried out under an argon atmosphere using standard Schlenk techniques. NiA C H T U N G T R E N N U N G (cod) 2 , [26] PtCl 2 A C H T U N G T R E N N U N G (cod) [27] and HCN [28] were synthesized according to literature procedures. NMR spectra were recorded on a Varian Unity Inova 500 (VT NMR …”

“…[7] Moreover, the diphosphinite ligand containing elec- ) vibrations of CO in (L)Ni(CO) 2 complexes. This CF 3 -diphosphinite system, reported by RajanBabu et al, performed best in the hydrocyanation of 6-methoxy-2-vinylnaphthalene in terms of activity and enantioselectivity.…”

Efficient nickel-catalyzed hydrocyanation of alkenes using acetone cyanohydrin as a safer cyano source

“…2 To date, various methods have been reported for the preparation of nitriles. 3 Pioneering examples of alkene hydrocyanation using homogeneous Co(0) have been reported, 4 and Pd(0) 5 and Ni(0) 6 catalyst systems have also been proposed, with Ni(0)-promoted hydrocyanation being developed recently. 7 In particular, the DuPont adiponitrile synthesis is one of the most studied processes.…”

Access to 1,3‐Dinitriles by Enantioselective Auto‐tandem Catalysis: Merging Allylic Cyanation with Asymmetric Hydrocyanation

“…[12] Since 1979, various synthetic methods for obtaining chiral nitriles through asymmetric hydrocyanation have been achieved due to the emergence/utilization of wide variety of chiral ligands. [12] However, it should be noted that such strategies are restricted to strained alkenes, [13] vinylarenes, [14] 1,3-dienes [15a,b] and allenes [15c] as prochiral substrates. In 1992, RajanBabu and Casalnuovo developed a Ni-catalyzed asymmetric hydrocyanation of 2-methoxy-6-vinyl-naphthalene with sugar-derived diphosphonite ligand L1, which led to corresponding nitriles with excellent levels of enantiocon- trol.…”