106138-91-4Relevant academic research and scientific papers
Reactivity of 1-Aza-4-oxa-1,3-butadienes (α -imino ketones) toward diorganozinc reagents: Regio- and chemoselective transfer of organo groups in the ZnR2/R1N=C(R2)C(R3)=O system and x-ray structure of the organozinc enolate [EtZn(Et)(t-Bu)NC(H)=C(Me)O]2
Van Vliet, M. Robert P.,Van Koten, Gerard,Buysingh, Paul,Jastrzebski, Johann T. B. H.,Spek, Anthony L.
, p. 537 - 546 (2008/10/08)
The 1:1 reaction of ZnR2 with α-imino ketones [R1N=C(R2)C(R3)=O] leads to quantitative formation of dinuclear [RZn(R)(R1)NC(R2)=C(R3)O]2 (1) (for R = primary and secondary alkyls) and [RZn(R1)-N=C(R2)C(R3,R)O]2 (2) (for R = aryl, methyl, and tertiary alkyl). An X-ray structure determination of [EtZn(Et)(t-Bu)NC(H)=C(Me)O]2 (1a) has established the dinuclear structure that consists of a N,O-chelate coordinated [Et(t-Bu)NC(H)=C(Me)O]- monoanionic ligand and a central four-membered Zn2O2 ring formed by intermolecular Zn-O coordination. The Zn atoms are tetrahedrally surrounded by two O atoms, one N atom, and one C atom. Crystals of 1a are triclinic, space group P1, with cell constants a = 7.57 (1) A?, b = 8.82 (2) A?, c = 11.14 (1) A?, α = 102.6 (1)°, β = 91.8 (1)°, γ = 114.4 (2)°, and Z = 1. The structure was refined to a final R of 0.089 with 1051 reflections. Product formation in the ZnR2/α-imino ketone system depends on the nature of the R group that migrates from Zn to the NCCO skeleton. Different radical activity of R (for R = Et, i-Pr, t-Bu, and Bz) as generated in the 1:1 complex, with the ligand bonded in the N,O-chelate coordination mode (see A in Scheme II), is the predominant factor for the discrimination between imino N-addition (for R? = Et, i-Pr, and Bz; 20%) and carbonyl C-addition (R? = t-Bu and Bz; 80%). For R = Me and p-tolyl alternative routes involving a N-monodentate coordination mode and/or heterolytic activation may also account for the exclusive formation of carbonyl C-addition products.
