Bromides styryl

Another related photocyclodehydrogenation synthesis uses an N- styrylpyridinone (164 Scheme 92), which is generated by N- alkylation of pyridinone with a styryl bromide. Irradiation in acid solution in the presence of oxygen causes isomerization and cyclodehydrogenation to afford 4//-benzo[a]quinolizin-4-one (165) and its 7-phenyl derivative (166) in yields of 37% and 60% respectively (77JOC1122). 

The results published thereafter by Kochi s group are especially interesting from a mechanistic point of view . Indeed, for preparative chemistry the yields are not satisfactory and the reaction is limited to reactive alkenyl bromides such as propenyl and styryl bromides (Table 4). Neumann and Kochi were the first to replace iron(III) chloride by iron(III) acetylacetonate or related complexes such as Fe(dbm)3 (iron tris-dibenzoylmethanato) that are less hygroscopic and easier to handle. 

Methylquinolizinium iodide (21, X = I) has been condensed with p-dimethylaminobenzaldehyde to yield the corresponding styryl derivative (22). Reaction of the same compound with p-nitrosodi-methylaniline affords the Schiff base 23.6 The simple 2-styrylquino-lizinium bromide was reported recently by Hansen and Amstutz.14... 

The styryl iodonium salt (7 a) reacts slowly with acetic acid to give the E and Z isomeric products (8a) and (9a) in the ratio 85 15.3 The decenyl system (7b) is much more reactive and gives only the inversion product, the Z isomer (9b). It was suggested that the styryl system reacts in a two-step mechanism via the vinylene phenonium ion (10), whereas the decenyl system follows a one-step vinylic. S n2 mechanism, hi contrast, 2-bromo-l-decenyliodonium salt reacts with bromide ion in MeCN with complete retention.4 The observed rate constants show an unexpected dependence on [Br ], in accordance with a mechanism involving ligand coupling within a bromoiodane intermediate. 

Sharkey20 found that living poly(methyl methacrylate) reacts efficiently and without side reaction with p-vinylbenzyl iodide (or bromide) at low temperature yielding poly(methyl methacrylate) macromonomers bearing at the chain end a styryl group (poly(methyl methacrylate)macromonomer). 

Another type of cationic initiation procedure starting from an unsaturated compound has been proposed 49). 3-Phenylallyl bromide is reacted in THF solution with AgSbF6 whereby a poly-THF macromonomer bearing a styryl residue at the chain end is formed ... 

The reaction was discovered by Dimroth, who synthesized a series of diaryl, dialkyl and aryl alkyl triazenes Vinyl triazenes were prepared in the same manner, thus phenyl azide and styryl-magnesium bromide afforded phenylstyryl triazene (120) in 54% yield... 

Oct-OPV5 and Ooct-OPV5 were prepared following a procedure that was used to prepare terf-butyl-end-substituted oligo(phenylene vinylenes) [43], Benzyltri-phenylphosphonium bromide was lengthened by a styryl unit via a Wittig reaction with 4-methylbenzaldehyde. The methyl group of the stilbene was functionalized by bromination with A -bromosuccinimide (NBS). The phosphonium salt of the stilbene was obtained by a subsequent reaction with triphenylphosphine in toluene. 

Trans-styryl magnesium bromide also afforded the coupling product in good yields. Ph Ph... 

A standard way to make vinyl boronic acids 237 is to hydroborate an alkyne with catechol borane38 235 and again hydrolyse the ester products 236. The empty orbital of the boron atom attacks the electron-rich terminus of the alkyne where is the larger HOMO of the Jt-bond. One detailed example39 includes Suzuki coupling to Z-styryl bromide. Another diester group commonly used in the Suzuki coupling is derived from pinacol - examples appear later. 

For example, mixing 6-oxo-3-styryl-l,4,5,6-tetrahydropyridazine with a three- to fourfold molar excess of certain aryl and a-naphthylmagne-sium bromides has been reported to yield the 4,5-dihydropyridazine 68... 

CH[PO(OH)2].CHBr.CO.CgH5, may be obtained by brominating -benzoyl-a-phenylethylphosphinie acid or by bromination as shown on p. 128 (compound III). It is a white, crystalline solid, M.pt. 196° C., converted by sodium carbonate, bicarbonate or hydroxide into phenyl styryl ketone, sodium bromide and sodium phosphate. When a boiling chloroform solution of the bromo-acid is treated with 1 equivalent of thionyl chloride, it yields the acid chloride, which with phenol gives the monophenyl ester, a crystalline product, M.pt. 179° C. The ester is best obtained by brominating phenyl jS-benzoyl-a-phenyl-ethylphosphinate described overpage it forms a sodium salt with cold dilute sodium hydroxide, but if the reaction be carried out with VOL. XI. III. 9... 

Benzylic Reactivity. 2,5-Dimethyl-3,4-dinitrothiophen has been condensed with aromatic aldehydes to give 3,4-dinitro-2,5-distyryl-thiophens. " An improved synthesis of 3-nitro-2-styryl-thiophens involves bromination of 3-methyl-2-nitrothiophen with A-bromosuccinimide, followed by a modified Wit-tig reaction. From 2,5-di(chloromethyl)thiophen, the phosphonate was prepared by the Arbusov reaction, which was used for the preparation of 2,5-distyryl-thiophens. Trichloromethyl(thienyl)carbinols have been converted into the corresponding fluoro-derivatives through the reaction with phenyl-tetrafluorophosphorane. The liquid-phase catalytic oxidation of phenyl-(2-thienyl)methane in acetic acid in the presence of cobalt(ll) acetate and sodium bromide has been investigated. ... 

Indolylmethylphosphonates (370) have been prepared from the corresponding bromides and undergo Wittig reactions with aryl aldehydes to yield styryl compounds (371) the 3-phenylthio group can be removed by reduction (Scheme 125) <85S188>. 

Copper(I) salt promoted reaction of styryl bromides with dibenzoyl disulfide in a hot aprotic polar solvent produces 2,4-diarylthiophenes (421) in moderate yields (Scheme 84) <92CL1947>. The reaction may involve addition of PhCOS radical to the double bond of the substrate (activated by copper(I) salt), further addition of the resulting radical (420) to the substrate, and intramolecular radical substitution with extrusion of benzoyl radical followed by elimination of hydrogen bromide. 

Scheme 12. TADDOL Precursors for Grafting (on Merrifield resin or on controlled-pore glass) and for Cross-Linking Suspension Copolymerization with Styrene. These TADDOL derivatives are prepared in the usual way from (suitably protected) components [21][78-81]. The zero- and first-generation Frechet-type [82] branches were attached by reaction of branch benzyl bromides with a TADDOL bearing four phenohc OH groups [22] [78] [79]. The cross-linked polymer beads we used had a diameter of ca. 400 pm. To keep the styryl derivatives from uncontroUed polymerization, they should be kept in the dark and in the cold.

---