Hexa-l,2,4,5-tetraene

An example is the synthesis of substituted [2.2]paracyclophanes as reported by Hopfet al When hexa-l,2,4,5-tetraene 23 is treated with dimethyl acetylenedi-carboxylate 24 (an electron-poor acetylenic dienophile), the initially formed reactive intermediate 25 dimerizes to yield the [2.2]paracyclophane 26 ... 

Radiolysis of the diacetylene hexa-l,5-diyne (50) generates the hexa-1,2,4,5-tetraene radical cation (51 +) via a Cope rearrangement in the Freon matrix. ... 

To demonstrate the quality of this simple approach we show in Figures 6 and 7 the PE spectra of 1,3-butadiene 2, (3 )-hexa-l,3,5-triene 161, (3E, 5 )-ocla-1,3,5,7-tetraene 234, [3]radialene 173, 3,4-dimethylidenecyclobutene 174 and fulvene 175. The observed positions I j1 of the tt-bands are collected in the third column of Table 2, and the eigenvalues xj obtained from standard HMO models in the fourth. A least-squares calculation yields the linear regression... 

CuFi2N4P2C24H28, Copper(II), (2,9-dimethyI-3,10-diphenyl-l, 4,8,11 -tetraazacyclotet-radeca-l,3,8,10-tetraene)-, bis[hexa-fluorophosphate(l-)], 22 10 Cul, Copper iodide, 22 101 CuN307SC,3H,4, Copper(II), (1,10-phenan-throline)[serinato(l-)]-, sulfate, 21 115 CUN4O2C10H18, Copper(II), [1,4,8,11-tetra-zacyclotetradecane-5,7-dionato(2-)]-, 23 83... 

The size of the K-system chosen has important implication on the structural and functional aspects of metal binding. To explore the size effect calculations were performed on the cation-ir complexes of Li+ and Mg + with the Jt-face of linear and cyclic unsaturated hydrocarbons [45]. In the case of the acyclic Jt-systems, we started with the simplest system, e.g. ethylene followed by buta-1,3-diene, hexa-l,3,5-triene, and octa-1,3,5, 7-tetraene with 2, 3 and 4, conjugated jt units, respectively. These linear systems with two and more number of jt units can have various conformations wherein the jt units can have cis, trans or a combination of both cis and trans orientations. Similarly for cyclic systems cyclobutadiene, benzene, cyclooctateraene, naphthalene, anthracene, phenanthrene and naphthacene have been included. Thus a wide range of sizes for aromatic systems have been covered. 

ClCoNgOTSjCgH, HjO, Cobalt(III), aqua-chlorobi (l,2-ethanediamine)-, dithionate, irons-, monohydrate, 21 125 CIFJ94PZnCg4Hg 2inc(n), chloro(2,9-di-methyl-3,IO-diphenyl-l, 4,8,1 l-tetraazacy-clotetradeca-l,3,8,IO-tetraene)-, hexa-fluorophosphate( I —), 22 111 ClF.TlCigHg, Thalliumdll), chlorobis(2,3,4,6-tetrafluorophenyl-), chlorobis(2,3,5,6-tetrafluorophenyl)-, 21 73 aF TIC,j, Thalliumdll), chlo-... 

The precursor for the syntheses oflupinine (926) was (Z)-hexa-2,5-dienol (1068), epoxidation of which with either l-(+)- or d-(—)-diethyl tartrate gave the expected (2R,3S) and (2S,3R)-epoxides, respectively, both in 90% ee. The former was converted via the tetraene (3R,4R)-1069 into (—)-926 in 82% yield and 86.5% ee, while the latter was transformed in analogous fashion into (T)-lupinine (ent-926) (ee 85.9%). The versatility of the double ring-closing metathesis that is central to these reactions was further demonstrated by the conversion of a range of homologous tetraenes into l-azabicyclo[m.n.O]alkadienones (m, n = 4, 5). 

Dienes react with molybdenum hexacarbonyl to give complexes of the type [Mo(CO)4(diene)] and [Mo(CO)2(diene)2], which are generally yellow, soluble in organic solvents, and readily sublimed. Cyclo-octa-1,5-diene (12, 79, 151), bicyclo[2,2,l]hepta-2,5-diene (175), a dimer of cyclo-octa-tetraene (12) and dimethyldivinylsilane (158) give the former type of complex with the structure (VI M = Mo), while butadiene (81) and cyclo-hexa-1,3-diene form the latter type (80). Tetracyclone gives the complex [Mo(CO)2(tetracyclone)2] (215). 

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