1 -Cyclohexenecarboxylic acid

Reports of nucleophilic vinylic photosubstitution reactions, which occur via the S l mechanism, are conspicuously scarce. One such example is the cobalt carbonyl catalysed photostimulated carbonylation of vinylic halides339. By this method 1-bromo and 1-chlorocyclohexene are converted into 1-cyclohexenecarboxylic acid in 98 and 97% yield, respectively. In a prototype vinylic S l reaction, of / -bromostyrene with the enolate anion CH2COCMe3, an ionic elimination-addition route seems to be followed along with the S l route340. 

Cyclohexenyl isocyanate (108), produced from 1-cyclohexenecarboxylic acid (107) and DPPA in situ, reacts with l-(A -pyrrolidinyl)cyclohexene (109) to give the pyridone derivative (110 equation 43). The similar vinyl isocyanate-enamine cyclocondensation presents a general method for the preparation of various pyridone derivatives. 

An example of the solvent effect is also seen in the reaction of 3-acryloyl-l,3-oxazolidin-2-one (15b) which did not give sufficient asymmetric induction by the previous method.(18) The reaction of 15b with butadiene in 1,3,5-TMB gives the 3-cyclohexenecarboxylic acid derivative 22 in 77% optical purity. 

Similarly, cyclohexene can be used as a source of cyclohexenecarboxylic acid 503.281... 

It has been shown that the hydrolysis of the monoester of 3-cyclohexenecarboxylic acid in H218 O gave 3,4-dihydroxycyclohexanecarboxylic acid with no lsO incorporation, which implies that cleavage occurs at the Os—O bonds.530... 

Cyclohexanediones, 123 Cyclohexenecarboxylic acid chloride, 499 Cyclohexene oxide, 10, 505... 

For example, reaction of cyclohexenecarboxylic acid chloride (1) in CH2CI2 with trimethylvinylsilane in the presence of stannic chloride at —30° and finally at 20° leads to the bicyclic enone 2 in 46% yield. The reaction involves an intermediate dienone (a) that cyclizes under acidic conditions (Nazarov reaction). Although yields are not high, this one step synthesis of bicyclo[h.3.0]enones is very convenient. ... 

A cationic zirconocene complex formed by treatment of Cp2ZrCl2 with AgC104 has been found to catalyze Diels-Alder reactions [24]. For example, reaction of epoxy ester 55 with isoprene presumably proceeds via the formation of dioxolenium ion 56 then cyclization (Eq. 24). Hydrolysis gave cyclohexenecarboxylic acid 57. 

In the case of a sterically hindered allylic methoxycarbonyl group, the epoxida-tion of substituted cyclohexenes-1,4-dienes occurs on the opposite side. Further studies on the epoxidation of j3,7-unsaturated cyclohexenecarboxylic acids and esters indicate that the steric and polar effects of the COaMe group result mainly in anh -epoxidation while the carboxyl group in inert solvent exerts a syn directing effect. ... 

Taking in consideration that the anti-influenza drug and neuraminidase inhibitor GS-4071 has a cyclohexenecarboxylic acid structure, the cyclohexene phosphonate derivatives 114-123 (Fig. 10) were prepared and tested for TcTS activity.170 Compounds 115 and 117, containing the phosphonate as the monoethyl ester showed only weak inhibition (IC50 values of 4.7 and 5.7 mM, respectively). 

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