Cyclooctene aldehyde

The two double bonds in (I) are not both hydroformylated at the same rate. At 80-100 and 100 atm CO/Hg (1 1), only one of the double bonds reacts and cyclooctene aldehyde (IV) is formed. This can react further in two ways. At synthesis gas pressures above 200 atm, the second double bond is hydroformylated, at its original position, to a mixture of dialdehydes (V). Under 200 atm, the double bond is isomerized into conjugation with the aldehyde group. The a,p-unsaturated aldehyde (VI) is hydrogenated, slowly at 100 °C and rapidly at 150 °C, to the saturated aldehyde (VII), which may be hydrogenated to the monool (II) by raising the temperature to 210 °C. 

Isomerization of ( /Z) isomers is another important transformation. Isomerization of ( ) and (Z-) conjugated amides is effected photochemically " (photo-isomerization " ). There is a rather high energy barrier for the excited state required for (E/Z) isomerization. Isomerization of the C=C units in dienes is also induced photochemically. " Isomerization of cyclic alkenes is more difficult but cyclooctene is isomerized photochemically. " Conjugated aldehydes have been isomerized... 

The reaction can be extended to other cycloalkenes such as cyclooctene, 1,5-cyclooctadiene, or 1,5-cyclooctadiene resulting in ozonides that have, in addition to the geminal 3-methyl-3-carbomethoxy substituents, a heptanal or cis-heptenal group at position 5 (in the case of 1,3-cyclooctadiene this side chain has the double bond in the non-conjugated position relative to the aldehydic group) <1993TL6591>. 

Ans. 1,5-COD to cyclooctene cyclooctene plus ethylene metathesis to give Cio dialkene, which on selective hydrogenation followed by hydrofor-mylation will give the aldehyde. 

Cyclooctadiene (1,5-COD) is converted selectively to cyclooctene (97.8% on the addition of 1 mol of H2 per mol of diene) over a colloidal Pd supported on poly(N-vinyl-2-pyrrolidone) in methanol. The reaction is in part direct and in part proceeds through isomerization to the 1,4-COD, which is observed, and, presumably, through 1,3-COD, which is not observed. 1,3-COD is the most reactive and selective of the three dienes at its complete conversion it yields 99.9% cyclooctene. Nishimura discovered that the reduction of 1,5-COD is highly selective over Pd/CaCOa or Pd black in the presence of phenylacetalde-hyde with almost complete suppression of the reduction of cyclooctene. The inhibition is probably due to the decarbonylation of the aldehyde the adsorbed CO competes with the cyclooctene for surface sites. ... 

Cyclooctene treated with TBHP and ebselen gave the epoxide accompanied by trace amounts of 3-hydroxycyclo-octene resulting from a-hydroxylation <2001MI74>. Aromatic aldehydes with electron-donating substituents were... 

Oxidation. Oxidation of cyclohexene and norbomene with Mo(CO) -r-BuOOH in supercritical carbon dioxide gives vic-diols. Some alkenes (e.g., cyclooctene) afford epoxides but vinylnaphthalenes and cii-stilbene undergo oxidative cleavage to the aromatic aldehydes. 

Both oxetanes and p-hydroxy esters are formed following irradiation of aromatic carbonyl compounds in the presence of silyl ketene acetals. The products arise either by SET processes or by direct Paterno-Biichi additions. Griesbeck and Bondock have reported the influence of substrate concentration on the dia-stereoselectivity of the photochemical addition of aldehydes to (Z)- and ( )-cyclooctene. Miranda and co-workers have published physical evidence for the quenching of the triplet state of 2,4,6-triphenylpyrylium salts by 2,3-diaryloxetanes. 

Via stereoselective ethenolysis of 1,5-cyclooctadiene (COD), Bykov et al. [25] prepared l,d5-5,9-decatriene, a precursor for the synthesis of many ds-isomeric insect sex pheromone compounds. In the presence of the MoCl5/Si02/Me4Sn catalyst system, at 20 °C and an ethene pressure of 25 bar, a 80 % conversion of COD was obtained with a selectivity of 68.4% for l,ds-5,9-decatriene. From this triene, many long-chain (CiQ-Cig) unsaturated acetates, alcohols and aldehydes can be obtained with the required biologically active cis conformation. Cross-metathesis of cyclooctene with a-olefins in the presence of the same catalyst gave... 

Aryl transfers. Tran.sfer reactions involving arylboronic acids and aldehydes are catalyzed by (acac)Rh(cyclooctene)2. A large acceleration effect by t-BuiP is evident. ... 

Some aerobic oxidation reactions progress effectively in SCCO2 without a catalyst. Aerobic oxidation of olefins (e.g. cw-cyclooctene and (/f)-(-F)-limonene) in the presence of aldehydes (e.g. 2-methyl-propionaldehyde) in SCCO2 (d = 0.75 g/mL) gave the corresponding epoxides without a catalyst. It is speculated that the stainless steel from autoclave walls triggered the formation of acylperoxy radicals from the aldehyde and oxygen, and the reaction proceeded via a non-catalytic radical... 

Besides naturally occurring cyclic monoolefins, also synthetic analogs were screened. A typical example is cyclooctene (Scheme 6.16). Reaction of syngas with this cycloolefin in the presence of an unmodified Co catalyst under unusually smooth conditions in a >200 g scale gave cyclooctane carbaldehyde [87]. The product was converted into the corresponding acetals, a modification that enhances the intensive green note of the precursor aldehyde. Alternatively,... 

Undec-lO-enal is a widely employed synthetic aroma compound with a citrus, waxy, fatty odor accompanied by a green, soapy nuance. It can be produced by hydroformylation of 1,9-decadiene (Scheme 6.25). The required substrate is accessible, for example, by olefin disproportionation of cyclooctene with ethylene [100]. The diene was reacted with syngas in the presence of a heterogenized Rh catalyst in a flow reactor to give undec-lO-enal and 2-methyldec-9-enal in 80% overall yield and a slight dominance of the linear aldehyde. The isomers could be separated by distillation. The smell of the branched aldehyde is very similar to that of... 

From spectral analysis, we were able to detect protonated (broad signal at 8 8.72 ppm) and decondensated imine (aldehyde peak at 8 10.01 ppm), as well as two new signals in the alkyUdene region (8 16.91 and 8 17.62 ppm). Furthermore, we observed the formation of a peak at 8 11.61 ppm (Ar-OH), which wimessed the breaking of the Ru-O bond and the presumed formation of a new Ru-Cl bond. After 2 h, the addition of an amount of cyclooctene... 

MO studies have shown that the Diels-Alder reaction of substituted selenocar-bonyl compounds with buta-1,3-diene or 2-methoxybuta-1,3-diene proceeds through a concerted, asynchronous transition state. Q ,jS-Unsaturated seleno ketones and seleno aldehydes readily undergo 4 - - 2-cycloaddition with alkenes and 4 - - 2-dimerization. The reaction of phosphaacetylene (138) with buta-1,3-diene produces triphosphatri-cyclooctenes (139) through a sequence involving Diels-Alder, ene, and intramolecular 4 -I- 2-cycloadditions (Scheme 53). The 4 + 2-cycloaddition of phosphaalkynes with 5,8-bis(trimethylsilyl)cycloocta-l,3,6-triene (140) readily yields the tricyclodecadiene (142) via the bicyclic intermediate (141) (Scheme 54). "... 

During the mechanistic studies of estrogen biosynthesis, selective oxidation of androstene-3,17,19-trione (n) to the corresponding carboxylic acid was found to proceed by iron porphyrin complexes (Scheme 14A) [253]. On the basis of substituent effect on the benzaldehyde oxidation and kinetic isotope effect, direct hydrogen abstraction mechanism has been proposed [254]. The relative reactivity of aldehydes and alkenes is as follows cyclooctene, styrene > aldehyde, terminal alkene > a, 3-unsaturated ketone. 

If the ozonolysis reaction mixture is treated with an oxidizing agent such as hydrogen peroxide, carboxylic acids rather than aldehydes are produced. For example, the ozonolysis of cyclooctene with an oxidative workup yields octanedioic acid (suberic acid). This compound is one of several dicarbox-yhc acids excreted in large amounts by persons suffering from diabetes. 

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