Application of cyanophosphates in organic synthesis. Reactivity of .ALPHA.-cyano-.ALPHA.-diethylphosphonooxy anions.

Cyanide‐Catalyzed Additions of Acyl Phosphonates to Aldehydes: A New Acyl Donor for Benzoin‐Type Reactions

“…The use of KCN in DMF was successful, but led to concurrent regioisomerization of the unsymmetrical benzoin product. Reactivity decreased with alternative phase-transfer catalysts such as Bu 4 NBr and Bu 4 PBr; poorer conversion was also observed in THF and toluene. The conditions were further simplified with the use of undried, unpurified diethyl ether, without the need of an inert atmosphere.…”

“…[8] Considering the [1,2]-acyl migration implicit in these reactions, we viewed with some interest a report by Kurihara and co-workers describing cyanophosphate anions as effective nucleophilic partners with aldehyde electrophiles (3-M, Scheme 1). [4] It occurred to us that 3-M could be generated from an acyl phosphonate (1d) via [1,2]-phosphoryl migration. [9,10] Pending carbonyl addition, phosphoryl transfer, and retrocyanation, a complete catalytic cycle could be envisioned.…”

“…Spectral data correspond to those previously reported. [4] Analytical data for the title compound: 1…”

“…[1] Regioselectivity issues in the catalytic process have been addressed through the application of stoichiometrically-generated acyl anion equivalents. Metalated dithioacetals, [2] (silyloxy)nitriles [3] and (cyano)phosphates [4] are representative stoichiometrically-generated acyl anion equivalents employed to synthesize unsymmetrical benzoin products. While effective, these routes are not without attendant efficiency considerations: added steps in making the starting materials, stoichiometric reagents, and in the case of the dithiane chemistry, deprotection with Hg(II).…”

Generation and Reaction of Ammonium Ylides in Basic Two‐Phase Systems

“…System B is also recommended for the preparation of 4ad and 4af from 2a1 and α,β-unsaturated carbonyl compounds 3d and 3f, respectively (Table 1). Methacrylonitrile (5) and crotononitrile were allowed to react with 2a1 in systems A and B, but only the former nitrile formed one isomer of 1,2-dicyano-1-methyl-2-phenylcyclopropane (6) [22] in 27 % yield (Scheme 3). This reactivity pattern is not very surprising as decreased activity of α-and particularly β-substituted electrophilic alkenes in Michael reactions is well known.…”