Cyclohexenyl acids

Fig. 2. Partial gas chromatogram of total cyclic fatty acid methyl esters derived from a-linolenic acid. A Cp-Wax 52CB (25 m x 0.25 mm i.d., 0.20 pm film thickness) capillary column was used. There was an initial temperature of 160°C for 5 min followed by a program at 0.5°C/min to 180°C. Peaks a-h were cyclopentenyl acids and i-p were cyclohexenyl acids. Source Ref. 22.

Interpretation of the mass spectra of derivatives of the cyclohexenyl acids with a double bond at C-16 [e.g., 9-(2 -prop-iranj-l-enyl-cyclohex-cM-4-enyl)nonanoate Fig. 5B] was more difficult. A gap of 78 amu between m/z 248 and 326 suggested a cyclohexadiene structure, yet the presence of a retro Diels-Alder fragment (m/z 315) indicated only one double bond in the ring. The mass spectrum of the deuterated ester had gaps of 84 amu from m/z 248 to 332 and of 30 amu from m/z 332 to 362, clearly showing that there was only one double bond in the ring with the other at C-... 

GC separation of all sixteen CFAMs from heated linseed oil can be achieved by using two different columns (Fig. 5.11 Dobson, Christie and Sebedio, 1996c). In a study where only small amounts of material were available, this approach was used to show that in pregnant rats fed a diet containing CFAMs from heated linseed oil, a cyclohexenyl acid with an E double bond at C-8 was preferentially incorporated into the liver phospholipids of the dam and the pups (Sebedio et al, 1996b). 

Cyclopentene-l-carbonitrile (7.54) also reacted with N-bromosuccinimide to give an allylic bromide, 7.55.27 Subsequent reaction with ammonia displaced the bromine and acid hydrolysis of the nitrile led to 3-aminocyclopentene-l-carboxylic acid, 7.S6. Cyclohexenyl acid derivatives have also been used. Bromination of... 

The wM-diacetate 363 can be transformed into either enantiomer of the 4-substituted 2-cyclohexen-l-ol 364 via the enzymatic hydrolysis. By changing the relative reactivity of the allylic leaving groups (acetate and the more reactive carbonate), either enantiomer of 4-substituted cyclohexenyl acetate is accessible by choice. Then the enantioselective synthesis of (7 )- and (S)-5-substituted 1,3-cyclohexadienes 365 and 367 can be achieved. The Pd(II)-cat-alyzed acetoxylactonization of the diene acids affords the lactones 366 and 368 of different stereochemistry[310]. The tropane alkaloid skeletons 370 and 371 have been constructed based on this chemoselective Pd-catalyzed reactions of 6-benzyloxy-l,3-cycloheptadiene (369)[311]. 

This interpretation is supported by results on the acetolysis of the bicyclic tosylates 9 and 10. With 9, after three months in acetic acid at 150°C, 90% of the starting material was recovered. This means that both ionization to a cyclopropyl cation and a concerted ring opening must be extremely slow. The preferred disrotatory ring-opening process would lead to an impossibly strained structure, the /ran -cyclohexenyl cation. In contrast, the stereoisomer 10 reacts at least 2x10 more rapidly because it can proceed to a stable cis-cyclohexenyl cation ... 

Electrochemical fluorination of a-cyclohexenyl-substituted carboxylic (acetic, propanoic, butanoic, and pentanoic) acid esters (methyl, ethyl, and propyl) results in a series of both perfluoro-9-alkyl-7-oxabicyclo[4 3 OJnonanes and per-fluoro-8-alkoxy-9-alkyl-7-oxabicyclo[4.3.0]nonanes [<8S] (equation 19)... 

Ethyl 1-bromocyclohexanecarboxylate, when treated with magnesium in anhydrous ether-benzene with subsequent addition of cyclohexanone, yields ethyl l-(l-hydroxycyclohexyl)cyclo-hexanecarboxylate. Dehydration and saponification give rise to l-(l-cyclohexenyl)cyclohexanecarboxylic acid, which upon decarboxylation at 195° yields cyclohexylidenecyclohexane in 8% overall yield, m.p. 540.4 This olefin has also been prepared by the debromination of 1,1 -dibromobicyclohexyl with zinc in acetic acid. ... 

High syn selectivity can be obtained from the addition of enamines to nitroalkenes. The reaction of 4-(1-cyclohexenyl)morpholine with ( )-l-bromo-4-(2-nitroethenyl)benzene gives, after acid hydrolysis, exclusively the. ryw-adduct, the relative configuration of which was unequivocally... 

The conformationally locked racemic enamine, 4-(4-rOT-butyl-1-cyclohexenyl)morpholine, reacts with (l-nitroethenyl)benzene to give a mixture of diastereomeric 1,2-oxazine 2-oxides 1 and 2 (ratio 1/2 75 25). Whether these arise via an ionic or a cycloaddition mechanism is unclear. Hydrolysis of 1 and 2 with dilute acid gave a 80 20 mixture of trans- and cis-ketones, 3 and 414. 

Acetic acid, butyl ester Acetic acid, pentyl ester Acetic acid, decyl ester Acetic acid, benzyl ester Acetic acid, benzyl ester Acetic acid, 1-cyclohexenyl ester Acetic acid, 3-cyclohexenyl ester Butyric acid, benzyl ester Phenylacetic acid, propyl ester Oleic acid, methyl ester Linoleic acid, methyl ester Linolenic acid, methyl ester Adipic acid, methyl ester Adipic acid, ethyl ester Adipic acid, diethyl ester Adipic acid, dipropyl ester Adipic acid, (methylethyl)ester Adipic acid,... 

A mixture of diphenyl-3-(2-morpholino-l-cyclohexenyl)phosphine sulfide (3.25 g, 8.5 mmol) and triethylamine (0.91 g, 9 mmol) in benzene (20 ml) was added to a solution of phosphorus tribromide (2.30 g, 8.5 mmol) in benzene (20 ml). After 2 h, a mixture of methanol (0.55 g, 17 mmol) and triethylamine (1.82 g, 18 mmol) in benzene (20 ml) was added with stirring to the solidified mass. After 1 h, the mixture was filtered, the filtrate was evaporated, and the residue was ground with petroleum ether. There was thus isolated pure dimethyl 3-dip henylthiophosphoryl-2-morpholino-l-cyclohexenylphospho-nous acid of melting point (mp) 193-196°C (3.14 g, 78%). 

Majumdar published several aza-Claisen rearrangements of 2-cyclohexenyl-1-anilines 39 (R -R =(CH2)3, Table 2, entries 22-28) [14]. The reaction was carried out upon heating the reactant in EtOH/HCl. The corresponding 2-cy-clohexenylanilines 41 were obtained with 50 to 90% yield. The cyclization to give indole derivatives 42 could be achieved in a separate step treatment of the rearrangement products 41 with Hg(OAc)2 in a suitable alcohol in the presence of acetic acid induced formation of the tetrahydrocarbazole 42. The tricyclic products 42 were synthesized with 70-85% yield. Finally, carbazoles could be obtained after DDQ dehydrogenation. 

METHOD 2. A mixture of 170 g of piperidine, 220 g of cyclohexylamine, and 750 ml of benzene is azeotropically distilled until the evolution of H2O stops, then vacuum distill to get cyclohexenyl-piperidine. p-toluenesulfonic acid monohydrate (190 g) in 250 ml of PhMe is heated under a water trap until all the H2O is removed, then add a solution of 165 g of cyclohexyl-piperidine in 500 ml of Et20, with cooling, to keep temp at 0°. A solution of 1 mole of PlMgBr (made from 157 g of PhBr and 24 g of Mg) in 750 ml of Et20 is added (still holding the temp at 0° to 5°). The mixture is stirred for an additional 30 min... 

Acetic acid 2-hydroxy-3-oxo-3-phenylpropyl ester 3 - Acetoxy-1 -cyclohexene 17)3-Acetoxy-estr-5(10)-ene-3-one rrara-Cyclohexenyl diacetate 4-Acetyl- 1-Methylcyclohexene 3-(Azidopropenyl)benzene... 

Cyclic thioureas such as 2-thiouracil 1118 (R = H), its 6-methyl 1118 (R = Me) and 6-propyl derivatives 1118 (R = Pr), as well as thiobarbital 1119 are effective agents against hyperthyroidism, while thiamylal 1120 is used as an anesthetic. A large number of barbituric acid derivatives have hypnotic or sedative effects, and allobarbital 1121 (R = R = allyl), aprobarbital 1121 (R = allyl, R = r-Pr), cyclobarbital 1121 (R = Et, R = 1-cyclohexenyl), pentobarbital 1121 (R = Et, R = 2-pentyl), phenobarbital 1121 (R = Et, R = Ph), propallyonal 1121 (R = isopropyl, R = 2-bromoallyl), and secobarbital 1121 (R = allyl, R = 2-pentyl) are all examples of N-unsubstituted barbiturates, while hexobarbital 1122 represents an N-methylated derivative. 

The proposed mechanism for allyhc acetoxylation of cyclohexene is illustrated in Scheme 15. Pd -mediated activation of the allyhc C - H bond generates a Jt-allyl Pd intermediate. Coordination of BQ to the Pd center promotes nucleophilic attack by acetate on the coordinated allyl ligand, which yields cyclohexenyl acetate and a Pd -BQ complex. The latter species reacts with two equivalents of acetic acid to complete the cycle, forming Pd(OAc)2 and hydroquinone. The HQ product can be recycled to BQ if a suitable CO catalyst and/or stoichiometric oxidant are present in the reaction. This mechanism reveals that BQ is more than a reoxidant for the Pd catalyst. Mechanistic studies reveal that BQ is required to promote nucleophilic attack on the Jt-allyl fragment [25,204-206]. 

Materials. Chemically pure solvents and reagent grade ceric ammonium nitrate were used as received. Cumene hydroperoxide was purified via the sodium salt. Lucidol tert-butyl hydroperoxide was purified by low temperature crystallization. Tetralin hydroperoxide, cyclohexenyl hydroperoxide, and 2-phenylbutyl-2-hydroperoxide were prepared by hydrocarbon oxidation and purified by the usual means. 1,1-Diphenyl-ethyl hydroperoxide and triphenylmethyl hydroperoxide were prepared from the alcohols by the acid-catalyzed reaction with hydrogen peroxide (10). 

Muthusamy et al. (82) prepared a number of oxacyclic ether compounds from the tandem ylide formation-dipolar cycloaddition methodology. Their approach provides a synthetic tactic to compounds such as ambrosic acid, smitopsin, and linearol. Starting with either cyclopentane or cyclohexane templates, they prepared ylide sizes of five or six, which are trapped in an intermolecular cycloaddition reaction by the addition of DMAD. The products are isolated in good overall yield. In a second system, 2,5-disubstituted cyclohexenyl derivatives are utilized to generate the pendent ylide, then, A-phenylmaleimide is added in an intermolecular reaction, accessing highly substituted oxatricyclic derivatives such as 182 (Scheme 4.43). 

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