Carvone epoxidation

Epoxide is an important intermediate for various bioactive compounds, so the demand for the chiral epoxide is increasing. Epoxide hydrolase can hydrolyze epoxide enantioselectively (Figure 20).21 For example, Aspergillus niger was used for the hydrolysis of carvone epoxide (Figure 20(a)).2 11 In the reaction of styrene oxide, the... 

Oxygenated p-Menthanes. The conformations of dihydrocarvone (148), the diastereoisomeric pairs of the corresponding 1-hydroxy-compound, and some related substances have been studied by temperature-dependent c.d. The conformations of the various stereoisomers (149) of the reduction products of carvotanacetone epoxide, as well as some of the corresponding alcohols from carvone epoxide (150) have been examined through their Hn.m.r. spectra. ... 

The iridane part of jasminin has been synthesized. Mild alkaline hydrolysis of jasminin gave the triol (337). Synthesis of (337) was effected by Favorskii rearrangement of ( + )-carvone epoxide (338) which gave the parent acid of the ester (339) in 20 % yield. The assignment of the configuration of hydroxyl is based both on mechanistic grounds and on n.m.r. evidence [J(4,5a) = 5 Hz, J(4,5p) = 5 Hz, J(3,4) = 6 Hz]. Hydroboration of (339) lead directly to the desired triol (337). 

As a further application of the reaction, the conversion of an endocyclic double bond to an c.xo-methylene is possible[382]. The epoxidation of an cWo-alkene followed by diethylaluminum amide-mediated isomerization affords the allylic alcohol 583 with an exo double bond[383]. The hydroxy group is eliminated selectively by Pd-catalyzed hydrogenolysis after converting it into allylic formate, yielding the c.ro-methylene compound 584. The conversion of carvone (585) into l,3-disiloxy-4-methylenecyclohexane (586) is an example[382]. 

Construction of the A ring fragment starts with epoxidation of chiral d-carvone (114) to afford epoxide 115. 

Epoxide (25) is needed as an intermediate for reductive alkylation. How would you make it from carvone (24) ... 

In 1998, Yang and coworkers reported a series of (7 )-carvone derived ketones (63) containing a quaternary center at and various substituents at (Fig. 22) [119]. The ees of fran -stilbene oxide varied with different para and meta substituents when 63b was used as the catalyst. The major contribution for the observed ee difference is from the n-n electronic repulsion between the Cl atom of the catalyst and the phenyl group of the substrate. The substitution at also influences the epoxidation transition state via an electrostatic interaction between the polarized C -X bond and the phenyl ring on franx-stilbene (Table 6, entries 3-7, 10-14). In 2000, Solladie-Cavallo and coworkers reported a series of fluorinated carbocyclic ketones... 

C. Samples were withdrawn every two days from the samples stored at 45 C and every three days from the samples stored at 37 C. Pulled samples were stored in screw cap vials at 0 C until analsis by gas chromatography (GC). The products were monitored for the formation of limonene-1,2-epoxide and L-carvone, both oxidation products of d-limonene (3). 

Gas Chromatographic Analysis. The contribution of limonene-1, 2-epoxides and carvone to the development of oxidized flavor of encapsulated orange oil has been investigated (5). The concentrations of these two compounds were reported to provide a reliable index of the stability of the encapsulated orange oil. 

The identification of limonene-1,2-epoxides and carvone was accomplished by retention indices and mass spectra, obtained separately by GC-MS, in comparison to authentic reference compounds. 

Cold pressed orange oil contains over 95 by weight monoterpene hydrocarbons. The principal constituent, d-limonene, ranges from 83-97 percent (9), Limonene degradation has been well docu-meted in the literature (LO, 1 1). Anandaraman identified limonene-1,2-epoxide and carvone as two of the earliest degradation products of d-limonene (12, 13). 

A solution of 3-chloroperbenzoic acid (55%) in methylene chloride is cooled in an ice bath. (5R)-(-)-Carvone are added dropwise thereto so that the temperature does not rise above 20°C. The reaction mixture is stirred at room temperature for 3.5 h, whereby a precipitate of 3-chlorobenzoic acid forms. This suspension is stirred for 30 min and cooled with ice in order to complete the precipitation. The precipitate is filtered off and washed with hexane/methylene chloride (9 1). The filtrate is evaporated carefully. The thus-obtained oil (epoxide) is suspended in ice-water and treated with 3 N sulfuric acid while cooling in an ice bath so that the temperature does not rise above 20°C. The mixture is stirred at room temperature for 15 h. The pH is adjusted to 6.5 by adding 3 N sodium hydroxide solution. A small amount of 3-chlorobenzoic acid is filtered off. The aqueous phase is cooled to 0°C, whereupon sodium (meta)periodate are added in portions over 30 min so that the temperature does not rise above 20°C. After stirring at room temperature for 2 h sodium sulfite and sodium bicarbonate are added in succession. The suspension is filtered and the filtrate is extracted three times with methylene chloride each time. The combined organic phases are dried over sodium sulfate and evaporated. There is obtained (5R)-5-acetyl-2-methyl-2-cyclohexen-l-one (crystallized from hexane/ethyl acetate at 0°C). 

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