Palladium-Catalyzed Migratory Insertion of Isocyanides for Synthesis ofC-Phosphonoketenimines

Abstract

An efficient method for the synthesis of C-phosphonoketenimines through palladium-catalyzed migratory insertion of isocyanides has been developed for the first time. This procedure tolerates wide functional groups and has a good atom economy. Further transformations of the products, which are useful building blocks for the β-aminophosphonates, β-aminovinylphosphonates, and C-phosphorylated tetrazoles, indicate potential synthetic utility.

Ketenimines from Isocyanides and Allyl Carbonates: Palladium‐Catalyzed Synthesis of β,γ‐Unsaturated Amides and Tetrazoles

“…(2)]. [14] We report herein that the reaction of allyl ethyl carbonates 1 with isocyanides 2 in the presence of ac atalytic amount of Pd(OAc) 2 indeed afforded vinyl ketenimines 3,w hich were hydrolyzed upon flash column chromatography (FCC) on silica gel to b,g-unsaturated carboxamides 4 [Scheme 1, Eq. (3)].…”

“…(2)]. [14] We report herein that the reaction of allyl ethyl carbonates 1 with isocyanides 2 in the presence of ac atalytic amount of Pd(OAc) 2 We began our studies by using cinnamyl ethyl carbonate (1a)and tert-butyl isocyanide (2a)astest substrates ( Table 1). In the presence of palladium acetate (0.1 equiv) and triphenylphosphine (0.2 equiv), the reaction of 1a and 2a in THF at 50 8 8Cafforded ketenimine 3a in 76 %yield, as determined by NMR spectroscopy.FCC of the crude ketenimine 3aafforded the b,g-unsaturated carboxamide 4a in 50 %y ield.…”

Transition Metal and Inner Transition Metal Catalyzed Amide Derivatives Formation through Isocyanide Chemistry

“…Similarly, aminocarbonylation of -phosphate benzyl halides was also developed. 74 Furthermore, Qu, Chen, and co-workers found that nickel catalyzes aminocarbonylations of unactivated alkyl iodides with isocyanides. 75 Zhu and co-workers described a Subsequently, Chen, Chen, and co-workers reported the tandem reaction of allenes 67 with isocyanides to produce heteroarylacetamides 69 (Scheme 23).…”

α‐Oxo‐Ketenimines from Isocyanides and α‐Haloketones: Synthesis and Divergent Reactivity

“…Migratory insertion of isocyanide to (h 1 -allyl)-Pd complex followed by b-hydride elimination of the resulting allylimidoylpalladium intermediate [13] was proposed to account for the formation of ketenimines. [14] Independently,t he Yang group [15] and the group of Wu andJ iang [16] have developed similar approaches starting from 2-bromophosphonates andp ropargylic carbonates, respectively.A sacontinuation of this research program,w e becamei nterested in the reactiono fa-haloketones with isocyanides. In 1984, Crociani and co-workers reportedt hat reaction of 2-chloroacetone (6)w ith Pd(PPh 3 ) 4 afforded carbon sbondedp alladium complex 7 which,u pon addition of tert-butylisocyanide, was converted to enaminone complex 9 via the imidoylpalladium intermediate 8.…”