Carvones rearrangement

Another example of the utility of this reaction is the formation of enantiopure cycloheptenones from optically pure natural products like R-carvone. Hydroxylaminomethylcyclohexene 72 derived from -carvone rearranged to provide two compounds resulting from selective rearrangement of the vinyl carbon. While the alkene migrated into conjugation under the reaction conditions providing 10% of 74, the Tiffeneau-Demjanov reaction provided entry into optically-enriched cycloheptenones. ... 

Where multiple products are possible, the CMR and MBR have been employed to optimize conditions for formation of specific components of a reaction sequence. Examples discussed below, were obtained by heating organic substrates such as allyl phenyl ether [46] and carvone [47] in water. Rearrangements, addition or elimination of water and isomerizations occurred, with each transformation favored under tightly defined conditions. 

The main renewable resource for L-carvone is spearmint oil (Mentha spicata), which contains up to 75% of this flavour chemical. There also exists a synthetic process for the manufacturing of L-carvone, which is based on (-t)-limonene, which is available as a by-product of the citrus juice industry as a major component of orange peel oil (Scheme 13.4). The synthesis was developed in the nineteenth century and starts with the reaction of (-t)-limonene and nitrosyl chloride, which ensures the asymmetry of the ring. Treatment with base of the nitrosyl chloride adduct results in elimination of hydrogen chloride and rearrangement of the nitrosyl function to an oxime. Acid treatment of the oxime finally results in l-carvone. 

Both a- and P-pinenes are popular starting materials for the synthesis of other monoterpene chiral synthons such as carvone, terpineol, and camphor (vide infra). Reactions leading to other monoterpenes are briefly summarized in Figure 5.1. Treatment of a-pinene with lead tetraacetate followed by rearrangement gives trans-verbenyl acetate (7), which is hydrolyzed to yield trans-verbenol (8) 8 Subsequent oxidation of 8 gives verbenone (9), which can be reduced to give cw-verbenol... 

A re-investigation of the Diels-Alder addition of butadiene to (-)-carvone has led to a reassignment of the structures of the major adduct (126) and the minor adduct (127).216 The isolation of the diol (128) on treating the ketone (129) with methyl-magnesium iodide is the result of a [2,3] sigmatropic rearrangement to (130) 217 this rearrangement may find application in artemisyl synthesis. 

Other papers related to p-menthanes concern vinylaziridine formation from pulegone oxime and from carvone-NN-dimethylhydrazone methiodate,234 non-ozonolytic cleavage of 10-trichloromethyl-limonene,235 and the stereochemistry of 1-chloro-l-nitroso-p-menthanes236 and of dihydropinol rearrangements (cf. Vol. 2, p. 34).237... 

The monoterpenes 5(-i-)-carvone (10 Scheme 2, Nicolaou et al.) and / (—)-a-phellandrene (20 Scheme 3, Danishefsky et al.) are chosen as the starting materials for the syntheses of the diterpenoid skeleton of eleutherobin (1). Again, both routes require the separation of diastereo-mers by chromatography. The addition of 1-ethoxyvinyllithium to the TBS-protected aldehyde 13 (Scheme 2) leads to a mixture of diastereomeric alcohols (5 4 ratio in favor of the desired configuration at C8), which is separated by Nicolaou et al. after the alkynylation with ethynyl magnesium bromide in a later step. 13 was synthesized in close analogy to Trost et al. with bond formation between C9 and CIO via Claisen rearrangement (Scheme 2) [17]. 

Before the introduction of metal-ammonia solutions for the reduction of a,p-unsaturated carbonyl compounds,sodium, sodium amalgam, or zinc in protic media were most commonly employed for this purpose. Some early examples of their use include the conversion of carvone to dihydrocarvone with zinc in acid or alkaline medium, and of cholest-4-en-3-one to cholestanone with sodium in alcohol. These earlier methods are complicated by a variety of side reactions, such as over-reduction, dimerization, skeletal rearrangements, acid- or base-catalyzed isomerizations and aldol condensations, most of which can be significantly minimized by metal-ammonia reduction. 

E. Lee and co-workers demonstrated that the chlorohydrin derived from (+)-carvone undergoes a stereoselective Favorskii rearrangement to afford a highly substituted cyclopentane carboxylic acid derivative. This intermediate was then converted to (+)-dihydronepetalactone. When the THP-protected chlorohydrin was treated with sodium methoxide in methanol at room temperature, the rearrangement took place with excellent stereoselectivity (10 1) and high yield. Interestingly, the major product was the thermodynamically less stable cyclopentanecarboxylate. 

In order to determine the structure of the photochemical rearrangement product of carvone camphor in methanol, and to prove its structure, the research team of T. Gibson subjected the bicyclic carboxylic acid product to a degradation sequence, which commenced with the HVZ reaction, followed by dehydrohalogenation, dihydroxylation and glycol cleavage. 

Shing, T. K. M., Lee, C. M., Lo, H. Y. Synthesis of the CD ring in taxol from (S)-(+)-carvone. Tetrahedron Lett. 2001,42, 8361-8363. Marchand, A. P., Kumar, V. S., Hariprakasha, H. K. Synthesis of novel cage oxaheterocycles. J. Org. Chem. 2001,66, 2072-2077. Demnitz, F. W. J., Philippini, C., Raphael, R. A. Unexpected Rearrangement in the Peroxytrifluoroacetic Acid-Mediated Baeyer-Villiger Oxidation of trans-3p-Hydroxy-4,4,10p-trimethyl-9-decalone Forming a 7-Oxabicyclo[2.2.1]heptane. Structure Proof and Total Synthesis of ( )-Farnesiferol-C. J. Org. Chem. 1995, 60, 5114-5120. 

Lee, E., Yoon, C. H. Stereoseiective Favorskii rearrangement of carvone chiorohydrin expedient synthesis of (+)-dihydronepetaiactone and (+)-iridomyrmecin. J. Chem. See., Chem. Commun. 1994, 479-481. 

Favorskii rearrangement is of note, as is the use of carvone as a chiral starting material,and the anne-lation procedure that follows the rearrangement shown in Scheme 26. ... 

Thermal and mercury(ii)-catalysed [3,3]sigmatropic rearangement of allylic trichloroacetimidates and allylic pseudo-ureas" e.g. geraniol, linalool) are useful for the 1,3-transposition of hydroxy- and amino-groups the former is synthetically preferred. The [2,3]sigmatropic rearrangement of allylic sulphoxides has been used to effect an alkylative 1,3-carbonyl transposition of enones (e.g. carvone). ... 

The first chiral synthesis of (+)-tecomanine (55) was described by Kamet-ani and co-workers (Scheme 16) (204) and began with (-)-carvone (239) as the chiral starting material. Favorskii-type rearrangement of (+)-carvone... 

An alternative process for the production of (-)-carvone has recently been elaborated. Starting from (-i-)-limonene 1,2-epoxide, a regioselective rearrangement of the epoxide leads to (-)-carveol (trans- -.[2102-58-1] cis- -.[2102-59-2]). The reaction is effected by the use of a catalyst consisting of a combination of metal salts and phenolic compounds. 

The aldehyde has been prepared [165] from (-)-carvone, which was epoxydized and transformed into (+)- ram,-carveol. Orthoacetate Claisen rearrangement and saponification afforded the corresponding y,5-... 

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