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Cyclopentadiene carboxylic acid

Dimeric cyclopentadiene carboxylic acid results from the photolysis of ferrocene-l.l -dicarboxylic acid in alkaline solution 353>. Ferrocene-l.l -disulfonic acid forms (via its iron salt) [(CsHsSOa Fe] on irradiation in water 355>. [Pg.202]

A small number of pyrroles undergo addition of acetylenedi-carboxylic acid across the 2,5-positions yielding adducts similar to those obtained from cyclopentadiene. In the case of 1-benzylpyrrole and the acid, some (13) is formed, probably through the intermediary of a species such as (8) a strong case has been made for the supposition that the Diels-Alder reaction occurs in two distinct stages,... [Pg.128]

The present synthesis10 consists of two simple steps, uses readily available and inexpensive starting materials, and produces pure material in high overall yield. It is based on two observations that nonenolizable ketones may be cleaved to carboxylic acids by potassium ferf-butoxide-water,2 and that aryl 2 chlorophenyl ketones may be cleaved with loss of the 2-chlorophenyl group to give only one of the two possible acids.11 Other compounds prepared by this route include carboxycyclopentadienyltriearbonylmanganese [Manganese, tricar-bonyl[(l, 2,3,4,5- )-l-carboxy-2,4-cyclopentadien-l-yl]-] (79%)10 and... [Pg.30]

The Diels-Alder reaction between oxazolone and cyclopentadiene in water was investigated by Cativiela (Eq. 12.35).96 Although the reaction is very slow, the ( )-5(4H)-oxazolone reacted with cyclopentadiene in an aqueous medium for six days at room temperature to form the corresponding sprioxazolones in a 95% yield. The cycloadducts were then readily converted into amino-norbomane carboxylic acids. [Pg.397]

Ketenes easily add water,alcohols, amines and thiols to give derivatives of phosphorylated carboxylic acids ( -7). Phosphorylated ketenes undergo reactions of cyclo"aadition to vinyl ethers,diazomethane,styrene, cyclopentadiene, etc. From phosphorylated ketenes other phosphorylated cumulenes can be obtained,for example allenes,isocyanates,ketenimines... [Pg.248]

A new synthesis of isoxazoles is by successive treatment of a ketoxime with butyllithi-um, the ester of a carboxylic acid and sulfuric acid, e.g. 1 -> 2 (94S989). Hitrovinyl oximes 3 (R1, R3 = alkyl or aryl) undergo oxidative cyclization to isoxazoles 4 by the action of DDQ or iodine/potassium iodide (94JHC861). Flash-vacuum pyrolysis of the 1,3-dipolar cycloadduct 5 of acrylonitrile oxide to norbornadiene results in a retro-Diels-Alder reaction to give cyclopentadiene and 3-vinylisoxazole 6 (94CC2661). [Pg.192]

The concept of using an ester auxiliary which also contains a handle suitable for chelation was first disclosed in 1984/1985. Thus TiCU-promoted addition of cyclopentadiene to the acrylate of ethyl (S)-lactate (379) proceeded readily at -63 C to give (with a 39 1 endolexo preference) a 93 7 mixture of norbomenes (381a) and (382a), from which the major product (381a) was isolated by MPLC (Scheme 93, Table 23, entry 1). Mild saponification of adduct (381a) with LiOH in aqueous THF and purification via iodolactonization/elimination provided pure (l/ ,2/ )-5-norbomene-2-carboxylic acid. [Pg.365]

Prompted by the X-ray studies of the acryloyl lactate-TiCU complex (380a), commercially available pantolactone was chosen as an auxiliary aiming to facilitate entropically the formation of a seven-mem-bered titanium chelate (385). Indeed, using 0.1-0.75 mol equiv. of TiCU the acrylate and crotonate of (/ )-pantolactone (384) underwent smooth addition of cyclopentadiene, butadiene and isoprene to give adducts (386) and (387) in ratios of >93 <7 (Scheme 94, Table 24, entries a-d). Opposite product ratios were obtained using dienophiles (388) derived from (S)-pantolactone (entiy e) or (390) derived from the more readily available A -methyl-2-hydroxysuccinimide (entries f, g). The major products were purified by crystallization and saponified without epimerization (LiOH, THF/water, r.t.) to furnish the corresponding carboxylic acids. [Pg.365]

Another promising approach has been devised by Yamamoto and co-workers [8]. They found that the action of a controlled amount of diborane on a carboxylic acid leads to an (acyloxy)borane RC02BR 2 which behaves as a Lewis acid. The chiral (acyloxy)borane (CAB) complex 1 formed in situ from monoacyl tartaric acid and diborane is an excellent asymmetric catalyst (Eq. 8) for the Diels-Alder reaction of cyclopentadiene and acrylic acid (78 % ee) (Eq. 9) [8] or of cyclopentadiene and methacrolein (96 % ee) (Eq. 10) [9]. [Pg.139]

The reactions are very fast, and halide ion addition always leads to 77-allylpalladium halide dimers. The cyclopentadienyl moiety has been isolated in the form of cyclopentadiene (reaction with hydrogen chloride), or as a carboxylic acid dimer (reaction with BuLi -f CO2). That part of the attacking reagent bearing positive charge always combines with the C5H5... [Pg.388]


See other pages where Cyclopentadiene carboxylic acid is mentioned: [Pg.240]    [Pg.518]    [Pg.60]    [Pg.275]    [Pg.397]    [Pg.770]    [Pg.240]    [Pg.518]    [Pg.60]    [Pg.275]    [Pg.397]    [Pg.770]    [Pg.469]    [Pg.270]    [Pg.542]    [Pg.735]    [Pg.201]    [Pg.20]    [Pg.117]    [Pg.361]    [Pg.100]    [Pg.124]    [Pg.222]    [Pg.291]    [Pg.100]    [Pg.79]    [Pg.165]    [Pg.169]    [Pg.180]    [Pg.21]    [Pg.207]    [Pg.88]    [Pg.52]    [Pg.290]   
See also in sourсe #XX -- [ Pg.117 ]




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Cyclopentadiene acidity

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