2,6-Bis[1-(2-isopropyl­phenyl­imino)­ethyl]­pyridine

The title compound, C27H31N3, has E substitution at each imine double bond where the two N atoms adopt a trans–trans relationship. The benzene rings are twisted out of the mean plane of the pyridine ring; the mean planes of the aromatic groups are rotated by 63.0 (1) and 72.58 (8)°. The crystal structure is sustained mainly by C—H⋯π and hydro­phobic methyl–methyl inter­actions

(Z)-4-(2,5-Di-tert-butyl­anilino)pent-3-en-2-one

In the crystal structure of the title ketoamine, C19H29NO, the bond lengths from the N atom through the alkene group to the ketone O atom show the presence of an extensively delocalized π-system. The dihedral angle between the plane of the phenyl ring and that of the alkene component is 63.45 (7)° due to steric hindrance exerted by the tert-butyl groups. The mol­ecule has a Z-configured alkene function, which is facilitated by an intra­molecular N—H⋯O hydrogen bond between the amine and ketone groups. The mol­ecules are linked into extended chains, which run parallel to the [010] direction, by a very weak C—H⋯O inter­action between the methyl substituent of the alkene group and the ketone O atom of a neighbouring mol­ecule

(E)-3-(1-Naphthyl­amino)­methyl­ene-(+)-camphor

In the crystal structure of the title ketoamine {systematic name: (E)-1,7,7-trimethyl-3-[(1-naphthyl­amino)­methyl­idene]bicyclo­[2.2.1]heptan-2-one}, C21H23NO, there are two independent mol­ecules in the asymmetric unit. Both mol­ecules have an E configuration about the alkene function. The main conformational difference between the mol­ecules is in the orientation of the plane of the naphthyl rings with respect to the camphor fragment. The torsion angle about the enamine C—N bond is 21.3 (7)° for mol­ecule A, but −24.4 (8)° for mol­ecule B. Inter­molecular N—H⋯O hydrogen bonds between the amino and ketone groups of adjacent independent mol­ecules sustain the crystal, and the resulting extended chains, containing an alternating sequence of the two independent mol­ecules, run parallel to the [001] direction and can be described by a graph-set motif of C 2 2(12)

(4R)-3-Hydroxy-7-isopropyl-4-methyl-5,6-dihydrobenzofuran-2(4H)-one

In the title compound, alternatively called α-hydroxy-γ-alkylidenebutenolide, C12H16O3, two independent molecules (A and B) crystallize in the asymmetric unit in each of which the 5,6-dihydrobenzo ring has an envelope conformation. The torsion angle along the butadiene chain in the γ-alkylidenebutenolide core is −177.9 (2)° for molecule A and 179.9 (2)° for molecule B. In the crystal, O—H...O hydrogen bonds between hydroxyl and carbonyl groups of adjacent independent molecules form dimers with R22(10) loops

C2 and C1-Symmetric Camphopyrazole Dioxomolybdenum(VI) Complexes catalyze the Epoxidation of Cyclic Olefins

Dioxomolybdenum(VI) complexes (1‐6) were prepared in good yields (≥79 %) using enantiopure C$_{2}$ and C$_{1}$‐symmetric bidentate N,N‐ligands (L$_{1}$‐L$_{6}$) derived from (+)‐camphor. The ligands and complexes were characterized by NMR spectroscopy, IR, and elemental analysis. Single crystal X‐ray diffraction analyses of complexes 3, 4 and 6 confirmed the bidentate coordination modes of ligands L$_{3}$, L$_{4}$, and L$_{6}$ and revealed distorted octahedral coordination geometries around the metal center. Complexes 3 and 6 form conformational isomers depending on the orientation of the substituents of the ligand aryl groups. Preliminary evaluation of the complexes as catalysts for the epoxidation of cyclohexene (81–93 % conversion) and cis‐cyclooctene (66–94 % conversion) with cumyl hydroperoxide and 35 % w/w aqueous hydrogen peroxide (39–73 %) demonstrated their activity for oxygen atom transfer reactions, opening the way for asymmetric epoxidations

Camphopyrazole-based N,N- and N,P-ligands and chiral complexes of Ni, Pd, and Rh: P–N bond activation upon Rh(I) complexation

Enantiomerically pure C1 and C2-symmetric bidentate N,N- and N,P-ligands are accessible from (+)-camphor in good yields (60–90%). Modified syntheses of precursors 1 and 2 are disclosed as well as the crystal structures of three hydroxy-pyrazoline intermediates. Ligands 3, 4, 6, and 11 were fully characterized including an X-ray crystal structure of C2-symmetric 6, which showed an E-configuration in the solid state. These ligands form complexes with Ni(II), Pd(II), and Rh(I) in good yields (84–96%); the X-ray crystal structures of complexes 12, 14, and 16 confirmed the bidentate coordination modes of ligands 4, 6, and 11 and distorted tetrahedral [for Ni(II)] and square planar [for Rh(I)] coordination geometries. Furthermore, the structure of the Rh(I) complex 16 revealed the presence of a Ph2PCl ligand, which, along with spectroscopic data, is proof of an almost quantitative P–N bond cleavage upon coordination of ligand 11 to [RhCl(COD)]2

“Chiral-at-Metal” Hemilabile Nickel Complexes with a Latent d¹⁰-ML₂ Configuration: Receiving Substrates with Open Arms

Complexes with highly reactive stereogenic metal centers are of great interest to asymmetric synthesis. Thus, by reacting [Ni­(COD)₂] with 2 equiv of the P-alkene ligand (<i>S</i>)-<b>5</b> ((<i>S</i>)-(+)-<i>N</i>-(3,5-dioxa-4-phosphacyclohepta­[2,1-<i>a</i>;3,4-<i>a</i>′]­dinaphthalen-4-yl)­dibenz­[<i>b</i>,<i>f</i>]­azepine) or (<i>S</i>_<i>P</i><i>,S</i>_<i>C</i>)<i>-</i><b>6</b> ((2<i>S</i>,5<i>S</i>)-(-)-<i>N</i>-(aza-3-oxa-2-phosphabicyclo­[3.3.0]­octan-4-on-2-yl)­dibenz­[<i>b</i>,<i>f</i>]­azepine), the diastereomerically and enantiomerically pure tetrahedral complexes (Δ,<i>S,S</i>)-[Ni­(<b>5</b>-κ<i>P</i>,η²-alkene)₂] (<b>2a</b>) and (Δ,<i>S</i>_P<i>,S</i>_C<i>,S</i>_P<i>′</i><i>,S</i>_C<i>′</i>)-[Ni­(<b>6</b>-κ<i>P</i>,η²-alkene)₂] (<b>2b</b>) were obtained in almost quantitative yields on multigram scales. The Ni atoms showed in both cases stable Δ configurations. Even though these Ni(0) complexes were air stable in the solid state, once dissolved, complex <b>2a</b> readily activated CS₂, alkynes, and enones as the formal d¹⁰-ML₂ fragment [Ni­(<b>5</b>-κ<i>P</i>)₂] (<b>4</b>) to form adducts <b>8</b>–<b>11</b>. This is possible thanks to the decoordination of the hemilabile alkene arms of the P-alkene ligands, and the X-ray crystal structures of the CS₂ and 4-ethynyltoluene adducts confirmed the η² coordination modes of the substrates and the concomitant opening up of the alkene arms of ligand <b>5</b>. The coordination of α,β-unsaturated carbonyl compounds in complexes <b>11a</b>–<b>c</b> was reversible

“Chiral-at-Metal” Hemilabile Nickel Complexes with a Latent d¹⁰-ML₂ Configuration: Receiving Substrates with Open Arms

Complexes with highly reactive stereogenic metal centers are of great interest to asymmetric synthesis. Thus, by reacting [Ni­(COD)₂] with 2 equiv of the P-alkene ligand (<i>S</i>)-<b>5</b> ((<i>S</i>)-(+)-<i>N</i>-(3,5-dioxa-4-phosphacyclohepta­[2,1-<i>a</i>;3,4-<i>a</i>′]­dinaphthalen-4-yl)­dibenz­[<i>b</i>,<i>f</i>]­azepine) or (<i>S</i>_<i>P</i><i>,S</i>_<i>C</i>)<i>-</i><b>6</b> ((2<i>S</i>,5<i>S</i>)-(-)-<i>N</i>-(aza-3-oxa-2-phosphabicyclo­[3.3.0]­octan-4-on-2-yl)­dibenz­[<i>b</i>,<i>f</i>]­azepine), the diastereomerically and enantiomerically pure tetrahedral complexes (Δ,<i>S,S</i>)-[Ni­(<b>5</b>-κ<i>P</i>,η²-alkene)₂] (<b>2a</b>) and (Δ,<i>S</i>_P<i>,S</i>_C<i>,S</i>_P<i>′</i><i>,S</i>_C<i>′</i>)-[Ni­(<b>6</b>-κ<i>P</i>,η²-alkene)₂] (<b>2b</b>) were obtained in almost quantitative yields on multigram scales. The Ni atoms showed in both cases stable Δ configurations. Even though these Ni(0) complexes were air stable in the solid state, once dissolved, complex <b>2a</b> readily activated CS₂, alkynes, and enones as the formal d¹⁰-ML₂ fragment [Ni­(<b>5</b>-κ<i>P</i>)₂] (<b>4</b>) to form adducts <b>8</b>–<b>11</b>. This is possible thanks to the decoordination of the hemilabile alkene arms of the P-alkene ligands, and the X-ray crystal structures of the CS₂ and 4-ethynyltoluene adducts confirmed the η² coordination modes of the substrates and the concomitant opening up of the alkene arms of ligand <b>5</b>. The coordination of α,β-unsaturated carbonyl compounds in complexes <b>11a</b>–<b>c</b> was reversible