Nickel(0)-Catalyzed [2 + 2 + 1] Carbonylative Cycloaddition of Imines and Alkynes or Norbornene Leading to γ-Lactams

Abstract

The first nickel(0)-catalyzed [2 + 2 + 1] carbonylative cycloaddition reaction of imines and alkynes or norbornene has been achieved by employing phenyl formate as a CO source. With this method, a variety of N-benzenesulfonyl, -tosyl, and -phosphoryl-substituted γ-lactams can be prepared in good to high yields.

Two-step synthesis of chiral fused tricyclic scaffolds from phenols via desymmetrization on nickel

“…A N -tosyl analog of alkynyl-cyclohexadienone 1j failed to give the desired product 3jc with 2c under the present reaction conditions. This could have been due to coordination ability of tosyl group to nickel which inhibits the coordination of 2c 44, 45 . The absolute configurations of all five chiral centers in 3 were assigned according to an analogy with 3ik , which was unambiguously determined by X-ray crystallographic analysis (Fig.…”

Boraformylation and Silaformylation of Allenes

“…Formate esters,e specially aryl formates,a re known to decompose to liberate CO, [13] thereby enabling ab oraformylation reaction with the CO that is evolved in situ. However, hexyl formate was not converted when the reaction shown in Table 2, entry 1was conducted without both B 2 (pin) 2 and 1a.…”

Efficient Synthesis of Polycyclic γ‐Lactams by Catalytic Carbonylation of Ene‐Imines via Nickelacycle Intermediates

“…[4,5] These hetero-nickelacycles afforded the corresponding lactones and lactams in the presence of an excess amount of CO gas.H owever, the simultaneous formation of nickel(0) carbonyl complexes such as [Ni(CO) 3 L] was inevitable. [9] However,t he direct use of CO gas remains unsuccessful because of the rapid formation of [Ni(CO) 3 PCy 3 ](Scheme 1a). [1c, 6, 7] To overcome this limitation, we employed phenyl formate as aCOsource [8] to regulate the concentration of CO,asithas to be sufficiently high for the reaction with the nickelacycle intermediates,y et also sufficiently low to ensure the formation of [Ni(CO) 3 L].T hus,t he first nickel(0)-catalyzed [2+ +2+ +1] carbonylative cycloaddition was developed with imines and either alkynes or norbornene.…”