Neonepetalactone

Neonepetalactone, 61 (Fig. 1.2.3), a bioactive compound found to be quite attractive to cats [41], was isolated in 1965 from the leaves and galls of Actinidia polygama by T. Sakan et al. and its absolute configuration was determined in 1980 [41b]. As some syntheses of the racemic mixture or ex-chiral-pool syntheses had already been reported, we realized that our SAMP/RAMP hydrazone methodology would make it possible to develop a very short asymmetric synthesis of this bioactive 8-lactone. 

Since neonepetalactone is closely related to the iridoids described above, the total synthesis followed the same procedure (Scheme 1.2.14) leading to the desired natural product in 55% overall yield and excellent de and ee values of >96%. 

In sharp contreist, however. Scheme 5 gives an instance of a methyl carbanion being introduced largely in an SN2 type inversion stereochemistry. Note that the substrate carries a cyclopropane carbon doubly activated by 1,3-dicarbonyl groups. A possible explanation is given in Scheme 6. The reaction can be utilized in the selective synthesis of dl-neonepetalactone and its epimer. 

Isopropyl-6-methyl-1,2-benzenediol, 1-60124 5-Isopropyl-2-methyl-l, 3-benzenediol, 1-60125 5-Isopropyl-3-methyl-1,2-benzenediol, 1-60126 5-Isopropyl-4-methyl-1,3-benzenediol, 1-60127 Neonepetalactone, N-70027 Nepetalactone, N-60020... 

Among the monoterpenoid lactones, derivatives of the iridane series 600) have acquired limited importance as aroma substances. Nepetalactone (143) occurs in quantities of up to 78% in American oil of catnip Nepeta cataria L.) 490), while epinepetalactone (144) is the major constituent (70%) of the essential oil of Nepeta mussini L. 490). The essential oil of this species was also found to contain neonepetalactone (146) as well as the two saturated compounds a- and 5-dihydronepetalactones (147) and (148) 490, 518) and 5,9-dehydronepetalactone (145) 528). Both dihydro compounds (147) and (148) are structurally closely related to the iri-domyrmecins from Actinidia polygama 515, 516). Lactones (143) to (150) are aroma compounds which have a strong odor and which exert an attracting effect on Felidae 518, 519). 

Neomatabiol, T14 Neomenthol, T4 Neomenthylamine, T4 Neonepetalactone, T14 Neophorbol 13,20-diacetate, T39 Neopinocampheols, T9 Neosapogenins, T49 Neothujyl alcohol, T7 Neotigogenin, T49 Neoverbanol, T2 ... 

Camphorquinone, T12.8 3-Acetoxycyclooctyne, X2.6 Nepetalactone, T14.9 Isonepetalactone, T14.10 Cinerolone, T17.4 2-Ethoxy-2-phenylethanol, A22.10 Piperitenone oxide, T4.3 Neonepetalactone, T14.7... 

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