Piperitenone

The antimicrobial activity of piperitone oxide rich Mentha rotundifolia M. suaveolens) oil was investigated by Oumzil et al., who found it less significant than that of pulegone or piperitone rich oils. The biosynthesis of the two levorotatory diastereomers from (15,25)(+)-piperitenone oxide... 

Croteau R, Venkatachalam KV, Metabolism of monoterpenes Demonstration that (-l-)- t-isopulegone, not piperitenone, is the key intermediate in the conversion of (—)- isopiperitenone to (-l-)-pulegone in peppermint Mentha piperita), Arch Biochem Biophys 249 306—315, 1986. 

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

In a recent extensive overview on the biotransformation of terpenoids by Aspergillus spp., Noma and Asakawa [92] also mentioned a sixth pathway of limonene bioconversion the hydroxylation at the C-4 position to give / -mentha-1,8-dien-4-ol (111), Fig. (20), a compound also identified earlier as one of the bioconversion metabolites of limonene with Penicillium italicum [83]. In this review, the fifth pathway, leading to isopiperitenol (113) which is further oxidised to isopiperitenone (112) and its rearrangement product, piperitenone (114) is also discussed. 

The biotransformation of (K)-(+)-pulegone was also studied by a Japanese group [116]. The major bioconversion metabolite of this substrate with Botrytis allii was (-)-(1 / )-8-hydroxy-4-p-menthen-3-one. The secondary major product from this biotransformation was isolated and its structure established as piperitenone [117]. It is interesting to note that the same group also investigated the bioconversion of piperitone, the dihydrogenation product of piperitenone a strain of Rhizoctonia solani was found able to hydroxylate the substrate preferentially at the 6-position [118,119]. 

Recently, the biotransformation of (+)-pulegone and other monoterpenoid ketones, like (-)-piperitenone, (+)- and (-)-carvone, (-)-menthone and (-)-verbenone by yeasts and yeast-like fungi was also... 

Dodecanol Formaldehyde Ethyl isovalerate Piperitenone P-Elemene... 

Cymene-8-ol n-Decanal Geranyl acetate Piperitenone 1,8-Cineole Camphene... 

Takasago has patented an alternate route to /-menthol (22) (Scheme 12.36).131 Chirality is set by the rhodium catalyzed asymmetric hydrogenation of piperitenone (108). Although many chiral biaryl bisphosphines catalysts have been used, DTMB-SegPHOS (107c) produced pulegone (109) in 90% yield and 98% ee with an S/C ratio of 50,000.131... 

Rotundifolone (= Piperitenone oxide) Mentha longifolia, M. rotmdifolia, M. spicata (Lamiaceae) OD-R... 

The majority of this work is confined to the synthesis of the epoxy derivatives of natural terpenes bearing an exocyclic double bond (see table overleaf). The stereochemical course of the reaction is governed by the factors discussed in Section 4.5.1.3.1. Umbellulone 1 was smoothly converted under typical Weitz-Scheffer conditions to a single epoxyumbellulone 233. (+)-Pulegone 3 gave a mixture of cis- and /ram-epoxides in a ratio 64.5 35.5, while piperitenone oxide 6 yielded piperitenone dioxide 7 as the sole product34,35. Epoxidation of pinocarvone 8... 

Epoxidation of (+)-Piperitenone Oxide with Alkaline Hydrogen Peroxide Typical Procedure34 ... 

Alkylation of isovaleramide with 1,3-dichlorobut-2-ene yields (139) after methyl-ation acid-catalysed hydrolysis and internal aldol condensation gives ( )-piperitone. The value of piperitenone and isopiperitenone formation, probably via electrocyclic reaction of the pyrolytic acetic acid-elimination product from A - and A -isomers of (49), cannot be assessed in the absence of reaction yields. (S)-(-)-Pulegone is obtained in good yield from (- )-citronellol by oxidation with pyridinium chlorochromate followed by double-bond isomerization. Low-temperature reduction of ( —)-carvone to ( —)-cz5-carveol (140) and... 

Lippia wilmsii H.H. Pearson Leaves SD 1.1-2.2 limonene, piperitone, piperitenone 79,80... 

Access to 3-menthene-l,8-diol (670), one of the minor products isolated (as its 1-acetate) from incubation of 7-terpenyl acetate (671) with a suspension of cultured Nicotiana tabacum cells, was conveniently achieved by reduction of piperitenone epoxide (620) with lithium aluminum hydride. ... 

Hydrogenation. Catalyst derived from (codfyRhOTf and the SEGPHOS analogue 1 is instrumental for hydrogenation of piperitenone to (-)-menthol via pulegone. ... 

---