Ascertaining the correctness of the assigned central 3d transition metal in coordination complexes

A commentary is given on the article by Dittrich et al. [Acta Cryst. (2017), B73, 794–804] in this issue

Cascade metathesis reactions for the synthesis of taxane and isotaxane derivatives

Tricyclic isotaxane and taxane derivatives and have been synthesized by a very efficient cascade ring-closing dienyne metathesis (RCDEYM) reaction, which formed the A and B rings in one operation. When the alkyne is present at C13 (with no neighboring gem-dimethyl group), the RCEDYM reaction leads to 14,15-isotaxanes 16a,b and 18b with the gem-dimethyl group on the A ring. If the alkyne is at the C11 position (and thus flanked by a gem-dimethyl group), RCEDYM reaction only proceeds in the presence of a trisubstituted olefin at C13, which disfavors the competing diene ring-closing metathesis reaction, to give the tricyclic core of Taxol 44

Bioactive flavanones from Luma chequen

A bioassay-guided chemical study of a methanolic extract of fresh leaves of Luma chequen led to the isolation of lumaflavanones A (1), B (2) and C (3) whose structures are proposed on the basis of NMR spectroscopic data. The structure of lumaflavanone A was confirmed by X-ray analysis. Antifeedant (Spodoptera littoralis), brine shrimp (Artemia salina) and fungistatic (Botrytis cinerea) bioassays showed that while 3 was the most active in the first two assays the mixture of 1 and 2 was more effective as a fungistatic

Synthesis of the core framework of the cornexistins by intramolecular Nozaki-Hiyama-Kishi coupling

A new and direct approach to the construction of the core framework of the herbicidal natural products cornexistin and hydroxycornexistin has been developed. Formation of the nine-membered carbocycle found in the natural products has been accomplished by an intramolecular Nozaki-Hiyama-Kishi reaction between a vinylic iodide and an aldehyde. Good yields of carbocyclic products were obtained from the reaction, but diastereomeric mixtures of allylic alcohols were produced. The cyclisation reaction was successful irrespective of the relative configuration of the stereogenic centres in the cyclisation precursor

[1,2-Bis(diphenyl­phosphino)-1,2-dicarba-closo-dodeca­borane-κ2 P,P′][7,8-bis­(di­phenyl­phosphino)-7,8-dicarba-nido-undeca­borato-κ2 P,P′]gold(I)–dichloro­methane–water (2/1/1)

The title compound, [Au(C26H30B10P2)(C26H30B9P2)]·0.5CH2Cl2·0.5H2O, contains two independent complex mol­ecules in the asymmetric unit. The gold(I) centres display a distorted tetra­hedral geometry. The complex is stablized through weak intra­molecular π–π stacking (Cg⋯Cg = 4.17 Å) and edge-to-face inter­actions (H⋯Cg = 3.21 Å). Adjacent mol­ecules inter­act through C—H⋯π (H⋯Cg = 2.88 Å) and B—H⋯π (H⋯Cg = 3.15 Å) contacts, forming a three-dimensional network, with solvent mol­ecules occupying the cavities. One of the phenyl groups was disordered over two sites with occupancy factors of 0.65 and 0.35

Some Effects of Thyroxine-Reserpine Treatment on Growth of Mice

Thyroxine, reserpine, and a combination of the two drugs were given to white mice over a ten-week period. Effects on growth rate were noted. Data are presented which indicate that a sequence of thyroxine for two days and reserpine for one day, with the sequence repeated over the experimental period, proved to have greatest effect on growth rate

tert-Butyl 2-methyl-2-(4-nitro­benzo­yl)propanoate

The title compound, C15H19NO5, is bent with a dihedral angle of 61.8 (2)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). The dihedral angle of 0.8 (2)° between the mean planes of the nitro group and the benzene ring indicates near coplanarity. In the crystal, each mol­ecule is linked to four adjacent mol­ecules by weak C—H⋯O hydrogen-bonding inter­actions. Both benzene H atoms ortho to the ketone O atom form C—H⋯O hydrogen bonds with the keto O atoms of two neighboring mol­ecules (of the keto and ester groups, respectively), and the two other inter­actions involve the H atoms from a methyl group of the dimethyl residue, displaying C—H⋯O inter­actions with the O atoms of the nitro groups. These four inter­actions for each mol­ecule lead to the formation of two-dimensional sheets with a hydro­philic inter­ior, held together by weak hydrogen-bonded inter­actions, and a hydro­phobic exterior composed of protruding methyl groups which interst­ack with the methyl groups in adjacent sheets

tert-Butyl 2-benzoyl-2-methyl­propanoate

The title compound, C15H20O3, is bent with a dihedral angle of 67.28 (9)° between the mean planes of the phenyl ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, mol­ecules related by inversion symmetry are connected by weak C—H⋯O inter­actions into infinite chains. On one side of the mol­ecule there are two adjacent inter­actions between neighbouring mol­ecules involving the H atoms of methyl groups from the dimethyl groups and the O atoms of the ketone; on the other side, there are also two inter­actions to another adjacent mol­ecule involving the H atoms on the phenyl rings and the carbonyl O atoms of the ester functionality

tert-Butyl 2-methyl-2-(4-methyl­benzo­yl)propanoate

The title compound, C16H22O3, is bent with a dihedral angle of 75.3 (1)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, the mol­ecules are linked into infinite chains held together by weak C—H⋯O hydrogen-bonded inter­actions between an H atom on the benzene ring of one mol­ecule and an O atom on the ketone functionality of an adjacent mol­ecule. The chains are arranged with neighbouring tert-butyl and dimethyl groups on adjacent chains exhibiting hydro­phobic stacking, with short C—H⋯H—C contacts (2.37 Å) between adjacent chain