Oxidative cyclization of the pyrrole–imidazole alkaloids oroidin and sventrin in DMSO/TFA (1:1) yields oxazolines via nucleophilic attack of the carbonyl oxygen at the alkenyl double bond. Oxidation takes place in the benzylic position of the imidazole ring. On prolonged reaction times, the oxazoline ring is hydrolyzed yielding the corresponding ester of pyrrole-2-carboxylic acid containing a f...

We have designed a new sequential carbocupration and sulfur-lithium exchange that leads stereo- and regioselectively to trisubstituted alkenyllithiums. Subsequent trapping with various electrophiles yields tetrasubstituted olefins with good control of the double-bond geometry (E/Z ratio up to 99:1). The novel sulfur-lithium exchange could be extended to the stereoselective preparation of Z-styr...

Photoreactions o f bacteriochlorophyll b have been studied. They all arise from reactions at the A8,8' double-bond. The A7,8-isomerisation product 3 is formed under anaerobic conditions. Irradiation in the presence of oxygen leads to three products arising from an autoxidation reaction involving singlet oxygen. The structures o f two o f them (4, 5) have been established from their methylpheoph...

Conformational analysis of modeled cis-unsaturated chains in triunsaturated and symmetrical monounsaturated triglycerides has identified pseudo-linear chain orientations that allow lower molecular mechanical energies than are possible with conventional cis-chains. Energy plots recorded during bond rotations near the double bond show that energy barriers between linear and normal cis-configurati...

We studied the pattern of the cis-trans isomerization of unsaturated fatty acids in cells of Pseudomonas putida S12 grown in a medium supplemented with oleic acid which was deuterated at both of the C atoms of its double bond. Direct evidence that isomerization does not include a transient saturation of the double bond was obtained. In addition, analysis of the amino acid sequences of the seven...

Reactions between magnesium 1,4-dihydropyridide or 1,2-dihydro-iso-quinolide derivatives and carbodiimides, RN[double bond, length as m-dash]C[double bond, length as m-dash]NR, generally result in Mg-N insertion and formation of guanidinate complexes. More sterically perturbed systems with N-aryl carbodiimide substitution, however, follow a divergent course of reaction initiating heterocyclic r...

The title compound, C(21)H(15)Cl(2)N(2)O(3), displays a trans configuration with respect to the C=N double bond. The mol-ecular conformation is stabilized by an intra-molecular O-H⋯N hydrogen bond.

A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followe...

The novel dimer [Cp(2)Zr[upper bond start]([minus sign in circle])S([plus sign in circle])CH(Ph)CH[double bond]C[upper bond end]PPh(2)](2), the first example of a structurally characterised sulfur-bridged binuclear zirconathiolane complex, was prepared, characterised by NMR spectroscopy and X-ray crystallography, and some aspects of its solution behaviour were studied.

Unsaturated bridges that link the two cyclopentadienyl ligands together in strained ansa metallocenes are rare and limited to carbon-carbon double bonds. The synthesis and isolation of a strained ferrocenophane containing an unsaturated two-boron bridge, isoelectronic with a C=C double bond, was achieved by reduction of a carbene-stabilized 1,1'-bis(dihaloboryl)ferrocene. A combination of spect...