Carvone, structure

FIGURE 9.1 Target bond maps for Nicolaou G5 and Ghosh plans for (-)-platensimycin showing superposition of (i )-carvone and (5)-carvone structures denoted by bolded bonds. 

Examine actual three-dimensional structures for the twc enantiomers of carvone. One occurs naturally in carawa> while the other is found in spearmint oil, and are responsible for the characteristic odors of these materials. Determine which form, R or S, is responsible for which odor. 

Carvone, a substance responsible for the odor of spearmint, has the following structure. Tell how many hydrogens are bonded to each carbon, and give the molecular formula of carvone. 

As is the case with many members of Lamiaceae, Satureja douglasii produces abundant essential oil from glandular trichomes on the leaves. Gas chromatographic analysis of the leaf oils from specimens collected throughout the species range revealed the presence of some dozen and a half well-known compounds. The major compounds identified were camphene [215], camphor [216], which, taken together, were considered to comprise the bicyclic type, carvone [217], pulegone [218], menthone [219], and isomenthone [220] (see Fig. 2.68 for structures 215-220). The predominance of each of these major components defined a terpene type. (All compounds were observed in each of the terpene types, most in comparatively small amounts, some only as traces.)... 

The major structural difference between monocyclic and bicyclic compounds should be obvious camphene and camphor exhibit bridged structures. It should be noted, however, that the monocyclic compounds can be further distinguished from each other based on the position of the oxygen atom, located at C-2 in carvone, and at C-3 in pulegone, and in the menthones. Work by others had shown that the... 

The mammalian olfactory system possesses enormous discriminatory power. It is claimed that humans can perceive many thousands of different odorous molecules, termed odorants. Even slight alterations in the structure of an odorant can lead to profound changes in perceived odor quality. One commonly cited example is carvone, whose L- and D-stereoisomers are perceived as spearmint and caraway, respectively. However, more subtle molecular alterations can also generate striking changes in perception. 

Equation (81)), while the other two C=C double bonds in the structure are intact. Under the same reaction conditions, the racemic carvone is also resolved kinetically with a KR/KS ratio of 33 1. Asymmetric hydrogenation of a,/Tacetylenic ketones to chiral propargylic alcohols is still unavailable. 

Aldehydes in this group are as follows carvone 36, dihydrocarvone 37, isom-enthone 38, piperitone 39, pulegone (piperitenone) 40, isopulegone 41 (Structure 4.9). 

The substituted cycloheptane monoterpenes, also called tropones. Eu-carvone 60, nezukone (4-isopropyl-2,4,6-cycloheptatrienone) 61 and y-thujaplicin 62 (Structure 4.14) most probably arise by an unknown ring expansion of the cyclohexane skeleton. 

The structure of 5-isothiocyanatopupukeanane (257), a sesquiterpene isothiocyanate from an Axinyssa species from Guam, was determined by X-ray analysis [260]. Two isomeric sesquiterpene thiocyanates, 2-thiocyanatoneopupukeanane (258) and 4-thiocyanatoneopupukeanane (259) were isolated from an unidentified sponge from Pohnpei and from Phycopsis terpnis from Okinawa [261]. A sample of Axinyssa (= Trachyopsis) aplysinoides from Palau yielded a rare thiocyanate, 2-thiocyanatopupukeanane (260), while two specimens from Pohnpei yielded 13-isothiocyanatocubebane (261), 1-isothiocyanatoaromadendrane (262) and 2-thiocyanatoneopupukeanane (258) [262]. This last compound had previously been assigned different stereochemistry at C2 [261]. (-)-4-Thiocyanatoneopupukeanane has been synthesised in an enantiospecific manner (259) [263]. Both enantiomers of 2-thiocyanatoneopupukeanane (258) have been synthesised from (7 )-carvone [264]. 

As mentioned before, a Pseudomonas incognita was isolated by enrichment technique on the monoterpene alcohol linalool that was also able to grow on geraniol, nerol and limonene [36]. The metabolism of limonene by this bacterium was also investigated [37]. After fermentation the medium yielded as main product a crystallic acid, perillic acid, together with unmetabolised limonene, and some oxygenated compounds dihydrocarvone, carvone, carveol, p-menth-8-en-1 -ol-2-one, p-menth-8-ene-1,2-diol or p-menth-1 -ene-6,9-diol (structure not fully elucidated) and finally / -isopropenyl pimelic acid. 

Absorption, metabolism, and biological activities of organic compounds are influenced by molecular interactions with asymmetric biomolecules. These interactions, which involve hydrophobic, electrostatic, inductive, dipole-dipole, hydrogen bonding, van der Waals forces, steric hindrance, and inclusion complex formation give rise to enantioselective differentiation. Within a series of similar structures, substantial differences in biological effects, molecular mechanism of action, distribution, or metabolic events may be observed. For example, (f )-carvone (I) has the odor of spearmint whereas (.Sb-carvone (2) has the odor of caraway. 

Harries et al(Refs 2 3) claimed to prepare the diozonide and the diozonide peroxide of carvone. Their structures were not detd. The diozonide was obtained as a yel oil on treating carvone in CCl4 with ozone, followed by purification with pett ether. It deconpd on standing with formation of formaldehyde. Further treatment of diozonide with ozone yielded diozonide peroxide, which exploded by itself after standing for several hrs in a freezing mixt. It expld almost instantly when treated with warm w or when rubbed with a glass rod Refs l)Beil 7, 153, (101) [l28] 2)Beil 7,... 

As another example of the effects of shape and molecular handedness, look at the substance called carvone. Left-handed carvone occurs in mint plants and has the characteristic odor of spearmint, while right-handed carvone occurs in several herbs and has the odor of caraway seeds. Again, the two structures are the same except for their shapes, yet they have entirely different odors. 

The structure of one of the enantiomers of carvone is shown here. Find the asymmetric carbon atom, and determine whether it has the (R) or the (5) configuration. 

The reaction of racemic 147 with (R)-carvone, initially at -78 °C followed by warming to room temperature for 1 h, gave the vinylcyclopropane 151 in 72% yield and moderate diastereoselectivity (d.r. = 75 25). The stereochemistry of the major diastereoisomer shown in structure 151 from H NMR studies was that expected based on the stereochemical outcome of the reaction of racemic 147 with the achiral cyclic enones 146 and is consistent with our previously proposed chelated transition state90 for cyclic enones (compare with the transition state B). 

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. 

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