Trans-verbenyl Acetate Research Articles

Autoxidation of limonene, α-pinene and β-pinene by dioxygen catalyzed by Co(OAc) 2/bromide

It has been shown that NaBr addition to Co(OAc) 2 increases conversions in autoxidations, by dioxygen, of limonene ( 1), α-pinene ( 2) and β-pinene ( 3). Best selectivities towards allylic oxygenated products were achieved with an optimum ratio [Co(OAc) 2] [NaBr] = 1 , while keeping [Co(OAc) 2] = 0.15 M. Using this system selectivities of 24.1, 11.4, 14.8 and 20.6% were obtained, respectively for carvone ( 4), trans-carveol ( 7a), trans- and cis-carvoyl acetate ( 9a and 9b) and 4-acetoxy- p-mentha-1,8-diene ( 13) from limonene ( 1). Autoxidation of α-pinene ( 2) showed selectivities of 10.2, 19.5 and 29.5% for myrtanal ( 6), verbenone ( 5) and trans-verbenyl acetate ( 17a), respectively. Very good selectivities, 19 and 15.4%, were observed for terpinyl acetate ( 27) and myrtanal ( 6) from autoxidation of β-pinene ( 3). Substitution of Co(II) by Mn(II) up to 30% M had no effect on conversions. However, this substitution (20–30% M) shifted selectivity significantly towards alcohols and acetates, yielding selectivities of 20 and 18% for trans-carveol ( 7a) and trans- and cis-carvoyl acetate ( 9a and 9b) from limonene ( 1); 48% for verbenyl acetate ( 17a) from α-pinene ( 2) and 16–18% for trans-pinocarveol ( 16) from β-pinene ( 3). It was concluded that, in this case, Mn(II) exercises a selectivity tuning effect.

Structural significance of the geminal-dimethyl group of (+)-trans-verbenyl acetate, sex pheromone mimic of the American cockroach

The significance of the geminal dimethyl group at C-6 of (+)-trans-veibenyl acetate (Ib), a sex pheromone mimic of the American cockroach, was investigated. Our interest was first directed to eliminating either methyl group of the geminal dimethyl group. Consequently, alcohols (IIIa and IVa) possessing a monomethyl group at C-6 were successfully obtained. Acetate (IVb) and propionate (IVc) of alcohol (IVa) possessing only a C-9 methyl group induced sex pheromonal activity at the 0.5 (IVb) and 0.02 mg (IVc) dose levels, respectively, while acetate (IIIb) of a alcohol (IIIa) with only C-8 methyl group was inactive. Alcohol (Va), which has an ethyl group at the C-6 instead of C-9 methyl, was also synthesized and converted into its acetate (Vb), which showed no activity. From these results, the significance of the dimethyl group is discussed relative to spatial requirements of the molecule for the receptor space. The M/F ratio in EAG was also evaluated for the synthesized esters. The M/F ratio index represented well the potency of pheromonal activity.

Sex pheromonal activity of (+)-bornyl acetate and related compounds to the American cockroach

Many compounds related to (+)-bornyl acetate (a sex phero-mone mimic of the American cockroach) were synthesized and tested for sex pheromonal activity. All compounds except for esters of (+)- and (-)-borneol were inactive, whereas (+)-bornyl acetate (Ib) and propionate (Ic) showed the activity at 0.05 mg. Although (-)-bornyl propionate (IVc) is the enantiomer of Ic, it exhibited weak activity at 0.5 mg dose. On the basis of the behavioral assay results, important chemical factors in Ib for pheromonal activity were elucidated and are discussed in connection with another mimic, (+)-trans-verbenyl acetate. The M/ F ratio index in EAG was evaluated for both active and inactive compounds. The index demonstrated a good correlation with the behavioral activity.

Structural significance of the alkyl substituent at the C-4 of (+)-trans-verbenyl acetate in sex pheromonal activity of the American cockroach

The significance of the alkyl group at the C-4 of (+)-trans-verbenyl acetate, which is the sex pheromone mimic of the American cockroach, was investigated. Seven alcohols possessing an ethyl, propyl, or dimethyl group at this position of the 6,6-dimethylbicyclo[3.1.1]heptane skeleton were synthesized and evaluated by behavioral assay. All of the alcohols were inactive, while three of four acetates of the 2α-alcohols induced sexual behavior in male cockroaches at the 0.02 or 0.5 mg dosage level, either of which is many orders of magnitude higher than the threshold level of the natural sex pheromones (10(-8) mg). Among the acetates, the compounds with a methyl group or an α-oriented ethyl group at C-4 showed the highest activity. The results are discussed in terms of spatial requirements of the molecules for interactions with the receptor.

Olfactory receptor responses of the nymphal American cockroach to sex pheromones and their mimics

1. 1. EAG responses to highly purified sex pheromones (periplanone-A and -B), sex pheromone mimics [germacrene-D, (+)-verbanyl acetate and (+)- trans-verbenyl acetate] and general odor (camphor) were recorded from both sexes of adult and three nymphal stages (7, 10 and 11th instars) of the American cockroach. 2. 2. The M/F ratios were evaluated for each stage by stimulation with the above chemicals. 3. 3. The ratio values indicated undeveloped sex pheromone receptor on the antennae of 7th male instar and females of all the stages. On the other hand, precursory development of the receptor was expected on the antennae of males of the old-aged nymphal instars and full development on the adult male antennae.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. Pat IX. Comparison of sex pheromonal activity on the American cockroach between acetates and propionates of verbenyl type alcohols.

Sex pheromonal activity was evaluated for propionates of 4 alcohols having a 6,6-dimethyl-bicyclo[3.1.1]heptane skeleton by behavioral assay with the male American cockroach. Their activities were compared with the corresponding acetates. The propionates were active at 20 μg or 500 μg, demonstrating stronger activities than the corresponding acetates. The male to female response ratio (M/F ratio) in EAG was also evaluated for the acetates and propionates, as well as for germacrene-D and camphor. The order of the behavioral activity was represented by that of the ratio. Sex pheromonal activity of (+)-verbanyl propionate (7) and germacrene-D were compared. Stronger activity was consequently observed in 7 at 5 μg dose, supporting the M/F ratio result.

Sex pheromonal activity of (+)-trans-verbenyl acetate and related compounds to the american cockroach,Periplaneta americana L.

The sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate, and 67 synthesized analogs were tested for sex pheromonal activity using males of the cockroach. Only three esters in addition to the original (+)-trans-verbenyl acetate exhibited activity. (+)-trans-Verbenyl propionate and (+)-verbanyl acetate in particular showed stronger activity than the original mimic. None of the other analogs caused a response at the 1-mg level. The lower threshold levels at which even the most active analogs showed activity (0.02 mg) were many orders of magnitude higher than that of the natural pheromone, periplanone-B (10(-8) mg). From the structure-activity relationships, important structural factors for sex pheromonal activity in the original mimic were discussed.

Male/female ratio in electroantennogram responses of the american cockroach to (+)- trans-verbenyl acetate and related compounds: Relationship between the ratio and sex pheromonal activity

1. 1. The male/female (M/F) ratio in the EAG response of the American cockroach were evaluated for the sex pheromone mimic, (+)- trans-verbenyl acetate, and its analogs, using the male and female EAG amplitudes at 50 μg on the lines which indicate the dose effect on the EAG amplitudes. 2. 2. The ratio values were related to the potency of sex pheromonal activity of the compounds. 3. 3. The ratio value increased with increase of pheromonal activity. 4. 4. The pheromonally inactive analogs were regarded as general odors from their small M/F ratio values.

Electroantennogram and behavioral responses of the American cockroach to sex pheromone mimics

1. 1. The EAG and behavioral responses to various amounts of sex pheromone mimics [germacrene-D, ( + )- trans-verbenyl acetate and ( + )- and (−)-bornyl acetate] and general odors (nerol and camphor) were examined in the American cockroach. 2. 2. The threshold EAG values of the stimuli were evaluated for male and female. 3. 3. The potency of sex pheromonal activity was evaluated by the behavioral assay. 4. 4. The M/F ratio values in EAG responses were connected with stimulating participation of the stimuli to the olfactory receptors. The ratio values seemed to be related to the potency of behavioral activity of the mimics.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. IV. Conformation of alcohols having apopinane skeleton.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. IV. Conformation of alcohols having apopinane skeleton.

Studies on the sex pheromone mimic of the American cockroch,(+)-trans-verbenyl acetate. Part V. Synthesis of configurational isomers of verbenyl carboxylic acid and related compounds.

Configurational isomers of verbenyl carboxylic acid and its derivatives were synthesized from (+)-α-pinene via a key intermediate, phenyl verbenyl sulfone. Configurations of the compounds were determined from stereochemical features in the reactions and the 1H- and 13C-NMR spectral properties.

Electroantennogram Responses from Parts of Antennae of the American Cockroach

Electroantennograms (EAG) were recorded from the distal, middle and basal parts of the antennae of adult male and female American cockroach. Stimulating chemicals employed were three sex pheromone mimics [(-)-bornyl acetate, (+)-trans-verbenyl acetate and germacrene-D] and a general odor (nerol). EAG responses produced from the male antennae were greater than those from females at any part of the antenna in all compounds. Among the antennal regions, the middle region was stimulated with the strongest EAG response in the male, whereas the distal region was most strongly stimulated in the female with any stimulus. From the above EAG results, the distribution of olfactory sensilla on the antennae is discussed along with the observations of morphologists.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. III. Conformation of pinan-3-ol derivatives.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. III. Conformation of pinan-3-ol derivatives.

Synthesis of verbenols and related alcohols and their PMR spectra with shift reagent.

In connection with our investigation on the structure-activity relationships of the American cockroach sex pheromone mimic, (+)-trans-verbenyl acetate, a number of alcohols having 6,6-dimethylbicyclo[3, 1. l]heptane skeleton were synthesized, and measured their PMR spectra in the presence of the shift reagent, Eu(dpm)3. The induced shifts of the 6, 6-gem-dimethyl protons and α-proton at the C–7 guided us to distinction between cis- and trans-alcohol. The configuration of secondary methyl groups was discussed from the induced shift values of the methyl protons.

Studies on the sex pheromone mimic of the American cockroach, (+)-trans-verbenyl acetate. II. Conformational analysis of verbenols and related alcohols by PMR spectra with a chemical shift reagent.

The conformation of cis- and trans-verbenol and five pairs of cis-trans alcohols having a 6, 6-dimethylbicyclo [3.1.1] heptane skeleton was analyzed using the PMR spectra under the influence of the chemical shift reagent, Eu(dpm)3. Inmost of such spectra, different proton signals appeared separately, and decoupling treatment in addition to direct analysis of the coupling constants of the separated signals enabled us to elucidate the conformation of the alcohols. The alcohols having a double bond took a “Y-shape”. The other alcohols were shown to be the “bridged boat” or “bridged chair” conformation in which the secondary methyl group exists always as a quasiequatorial.