1184-55-0Relevant articles and documents
Synthesis and characterisation of trigonal C2-chiral di- and tetra-substituted bis(oxazoline) alkyl zinc complexes and their reactivity towards protic reagents
Le Roux, Erwan,Merle, Nicolas,Toernroos, Karl W.
, p. 1768 - 1777 (2011)
A series of zinc(ii) alkyl complexes stabilised by the C2-chiral bis(oxazoline) ligand (R1,R2BOX, with R1 = (4S)-tBu, R2 = H (a); R1 = (4S)-Ph, R2 = H (b); R1 = (4R)-Ph, R2 = (5S)-Ph (c)), has been synthesised and structurally characterised. (R1,R2BOX)H ligands react with ZnEt2 in toluene to give the heteroleptic three-coordinate compounds of (R1,R2BOX)ZnEt, 1a, 1b and 1c in high yield. However, when the addition of (BOX)H ligands (a-b) over ZnEt2 is "uncontrolled", the formation of homoleptic four-coordinate compounds are favoured (2a-b), but not for the more sterically crowded ligand (c). The zinc-ethyl derivatives (1a-c) react readily with protic reagents such as acetic acid (HOAc) and methanol (MeOH). For compounds 1a-c a redistribution of ligands is observed leading preferentially to homoleptic compounds, except for the bulkier ligand c providing a three-coordinate complex identified as ( Ph,PhBOX)Zn(OMe), 4c. The reaction of acetylacetone (acacH) with compounds 1a-c leads straightforwardly to the more stable four-coordinate compounds corresponding to (R1,R2BOX)Zn(η2- acac), 5a-c. The potential of these compounds as initiators for the copolymerisation of epoxides with CO2 was investigated.
The Cyclopropane Ring as a Reporter of Radical Leaving-Group Reactivity for Ni-Catalyzed C(sp3)-O Arylation
Mills, L. Reginald,Monteith, John J.,Dos Passos Gomes, Gabriel,Aspuru-Guzik, Alán,Rousseaux, Sophie A. L.
supporting information, p. 13246 - 13254 (2020/09/01)
The ability to understand and predict reactivity is essential for the development of new reactions. In the context of Ni-catalyzed C(sp3)-O functionalization, we have developed a unique strategy employing activated cyclopropanols to aid the design and optimization of a redox-active leaving group for C(sp3)-O arylation. In this chemistry, the cyclopropane ring acts as a reporter of leaving-group reactivity, since the ring-opened product is obtained under polar (2e) conditions, and the ring-closed product is obtained under radical (1e) conditions. Mechanistic studies demonstrate that the optimal leaving group is redox-active and are consistent with a Ni(I)/Ni(III) catalytic cycle. The optimized reaction conditions are also used to synthesize a number of arylcyclopropanes, which are valuable pharmaceutical motifs.
Structure and reactivity of mono- and dinuclear diiminate zinc alkyl complexes
Allen, Scott D.,Moore, David R.,Lobkovsky, Emil B.,Coates, Geoffrey W.
, p. 137 - 148 (2007/10/03)
The synthesis, structure and reactivity of several diiminate ligands are presented. The syntheses of five representative β-diiminate (BDI) zinc alkyl complexes and one β-oxo-δ-diiminate (BODDI) zinc alkyl are described. BDI ligands with varying backbone and N -aryl substituents display different solid state structures. [(BDI)ZnR] are synthesized by the reaction of (BDI)H with ZnR2 in quantitative yield. Previously reported (BDI-1)ZnEt is a three-coordinate monomer in the solid state whereas [(BDI-3)ZnEt]∞ [(BDI-3)=2-((2,6-diisopropylphenyl) amido)-3-cyano-4-((2,6-diisopropylphenyl)imino-2-pentene] and [(BDI-4) ZnEt]∞ [(BDI-4)=2-((2,6-diethylphenyl)amido)-3-cyano-4- ((2,6-diethylphenyl)imino-2-pentene] form one dimensional coordination polymers. The bimetallic complex [(BODDI-1)(ZnEt)2] [(BODDI-1)=2,6-bis((2,6-diisopropylphenyl)amido)-2,5-heptadien-4-one] is prepared through the reaction of (BODDI-1)H2 with two equivalents ZnEt2. Both [(BDI)ZnEt] and [(BODDI)ZnEt] complexes react with acetic acid to give the acetate complexes in moderate to high yields, offering a superior synthetic route to these complexes. [(BDI)ZnR] [BDI=(BDI-3) or 1,1,1-trifluoro-2- ((2,6-diisopropylphenyl) amido)-4-((2,6-diethylphenyl)imino-2-pentene), (BDI-5)] complexes react with MeOH to produce [{(BDI)Zn(μ-OMe)} 2Zn(μ-OMe) 2] in moderate yields. The molecular structures of [(BDI-3)ZnEt], [(BDI-4)ZnEt], [(BODDI-1)(ZnEt) 2], [(BODDI-1) Zn2(μ-OAc)2], [{(BDI-3)Zn(μ-OMe)}2 Zn(μ-OMe)2] and [{(BDI-5)Zn(μ-OMe)}2 Zn(μ-OMe)2] have been determined by X-ray diffraction.
