Diastereoselectivity of Octahedral Cobalt(II) Pybox Complexes

Spin States of Homochiral and Heterochiral Isomers of [Fe(PyBox)2]2+ Derivatives

“…The influence of chirality on the spin states of homochiral and heterochiral diastereomers of [Fe(PyBox) 2 ] 2+ derivatives has been investigated. As has been noted for other [M( L Ph ) 2 ] 2+ complexes (M=Co, Cu and Zn), ( R )‐ 3 and ( R )‐ 4 adopt more distorted coordination geometries than ( RS )‐ 3 and ( RS )‐ 4 , which reflects a significant twisting of the ligand conformations in the homochiral isomers. Although this is sterically imposed, the precise origin of the effect is different in the two compounds.…”

“…This reflects a steric clash between ortho C−H groups on pairs of phenyl substituents in ( R )‐ 3 , which is not present in its ( RS )‐isomer (Figure ). The same ligand conformations are also adopted by other homo‐ and hetero‐chiral [M( L Ph ) 2 ] 2+ (M=Co, Cu or Zn) complexes in the crystalline phase. In contrast, the isopropyl substituents in ( R )‐ 4 exert a greater steric influence on the L i Pr ligand heterocyclic frameworks, but neighbouring pairs of i Pr groups are not in steric contact with each other (Figure ).…”

Detection of the Heterochirality of a 1:2 Metal/Ph-pybox Complex Ion by ESIMS

“…3,4 Williams has reported that heterochiral [Co(Sub-pybox) 2 ] was formed selectively when Sub was Ph; however, mixtures of homo-and heterochiral complexes were formed when Sub was Me and Bz. 5 This diastereoselectivity was explained by the avoidance of steric interference between Ph-substituents on different ligands in the heterochiral complex and the possibility of favorable ³-stacking interactions between the Ph-substituents of one pybox ligand with the pyridine ring of another pybox ligand. Aspinall found that the outcome of the reaction of Ln(OTf) 3 6 Although the metal dependency of the 1:2 metal/pybox complex structure is interesting, previous structural analysis was solely dependent on crystallographic analysis.…”

Expedient routes to 4,4-dialkyl- 5-methylene-1,3-oxazolines

“…In this case, the ring-closure proceeds during the work-up of the reaction mixture with aqueous alkali. In attempts to isolate the aromatic propargyl amide 3a diverse work-ups were employed, including neutralization with aqueous alkali or ammonia, and drying of the organic layer with K 2 CO 3 or MgSO 4 , but in all the cases only the corresponding 1,3-oxazoline 4a was isolated.…”

“…Recent investigations [1][2][3][4][5][6][7][8][9][10][11] have shown that 1,3-oxazolines (4,5-dihydro-oxazoles or 2-oxazolines)…”