5.7- Dimethyl-6,8-dioxabicyclo octan

IS)-endo,endo-5-Ethyl-2,4-dimethyl-6,8-dioxabicyclo-[3.2.1]-octane [54832-20-1]... 

Methyl- and 5,7-dimethyl-6,8-dioxabicyclo[3.2.1]octanes were polymerized in bulk in the presence of a large amount of boron trifluoride24. The resulting polymers having molecular weights of 900—1130 melted at 95—97 and 102—105 °C, respectively. 

The U.S. Forest Service scientists in New York have isolated and identified chemical sex attractants used by elm bark beetles that are responsible for transmitting the fungus causing Dutch elm disease. Examples of attractants are 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo [3.2.1] octane (called multistriatin) and 4-methyl-3-heptanol. In field trials an artificially produced mixture of the compounds has proved attractive to the elm bark beetle. 

B) Western balsam bark beetle, Dryocoetes confusus formation of endo-brevicomin [(1 F ,5S,7S)-7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1 ]octane] from ( )-6-nonen-2-one (Vanderwel et a/., 1992a) (C) Spruce beetle, Dendroctonus rufipennis formation of frontalin [(1S, 5fl)-(-)-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane] from 6-methyl-6-hepten-2-one (Perez ef a/., 1996 Francke etai, 1995 Francke and Schulz, 1999) (D) European elm bark beetle, Scolytus multistriatus hypothetical formation of oc-multistriatin [(1 S,2F ,4S,5F )-(-)-2,4-dimethyl-5-ethyl-6,8-dioxabicyclo[3.2.1]octane] from 4,6-dimethyl-7-octen-3-one (Francke and Schulz, 1999) and E The colored... 

Francke W., Schroder F., Kohnle U. and Simon M. (1996a) Synthesis of (lS,2R,5R)-2-ethyl-l,5-dimethyl-6,8-dioxabicyclo [3.2.1] octane, the aggregation pheromone of male beech bark beetle, Taphrorychus bicolor (Col., Scol.). Liebigs Ann. 10, 1523-1527. 

The frass of females of the western pine beetle Dendroctonus brevicomis is enriched with endo- (XIX) and exo-7-ethyl-5-methyl-6,8-dfoxabicyclot3.2.1]octane (XX), which are assigned the trivial epithets endo- and exo-brevicomin (61). Males of 2 brevicomis synthesize 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin) (XXI) in their hind guts (62), and this compound, in combination with the brevicomins and host-derived myrcene, constitutes a potent attractant for both sexes of J). brevicomis (63). Frontal in, also produced by females of . frontalis (62T7 is reported to function as a powerful aggregative pheromone when combined with host monoterpenes such as a-pinene (64). J). pseudotsugae... 

The terpenoid-exocrine theme emphasized by scolytid beetles was again evident when the chemical constitution of the secondary attractant for the smaller European elm bark beetle, Scolytus multistriatus, was elucidated. The aggregation pheromone was identified as a mixture of (-)-4-methyl-3-heptanol, 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo [3.2.1]octane (multistriatin) (XXII), and (-)-a-cubebene (XXIII), a host-derived synergist (70). All three compounds are required for the maximum attraction of beetles. The inactive diastereomers of 4-methyl-3-heptanol and multistriatin did not inhibit the responses of airborne beetles. 

The structure of (-)-a-multistriatin was found to be the structure (15, 2R, 45, 5/i)-(-)-2,4-dimethyl-5-ethyl-6,8-dioxabicyclo-[3.2.1]-octane (24a) (Mori, 1976 Pearce et al., 1976 Cemigliaro and Kocienski, 1977). However, populations of the beetle epidemic to forests in the Upper Rhine Valley did not aggregate in response to (- )-a-multistriatin instead, another of its stereoisomers, (- )-5-multistriatin (24b) exerted attractive action when combined with 23 and 25. 

Fig. 12.1 Aggregation pheromones of (a) Ips paraconfusus, three male-produced synergistic components - (+ )2-methyl-6-methylene-2,7-octadien-4-ol (ipsdienol) (-)2-methyl-6-methylene-7-octen-4-ol (ipsenol) and cw-verbenol. (b) Dendroctonus brevicomisj three attractive components, cxo-7-ethyl-5-methyl-6,8-dioxabicyclo-[3.2.1] octane (cxo-brevicomin) from the female l,5-dimethyl-6,8-dioxabicyclo-[3.2.1] octane (frontalin) from the male and myrcene released from the host tree. Verbenone and trans-verbenol, released after a male locates the female, interrupts response to the attractant blend.

Cl8H22N2O7 f 7-(l-p-Nitrobenzyloxycarbonyl)oxy-ethyl)-8-oxo-2,2-di-methyl-3-oxa-1-azabicyclo[4 2.0]octane, 46B, 383 Cl8H2 5CI2NO3, 1 i3-Acetoxy-5a,6a-(dichloromethano)-6 -morpholino-8a- -methyl-1, 2,3,5,6,7,8,8a-octahydronaphthalene, 39B, 263 Cl8H32N2O3, 5,8-Di-t-butyl-3,3-dimethyl-9-isopropylidene-5,8-diaza-4,7-dioxabicyclo[4.2.1]nonan-2-one, 4IB, 427... 

Figure 4 Experimental (in CCI4) and theoretical (ab initio DFT, B3LYP/6-31G ) spectra of (1R, 5S)-(+)-frontalin (A) absorption spectra, (B) VCD spectra. Reprinted with permission from Ashvar CS, Stephens PJ, Eggimann T and Wieser H (1998) Vibrational circular dichroism spectroscopy of chiral pheromones frontalin (1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane). Tetrahedron Asymmetry S 1107-1110. 1998 Elsevier Science B.V.

Chemoenzymatic asymmetric total synthesis of (S)-7,7-dimethyl -6,8-dioxabicyclo [3.2.1]octane, which is a volatile contributor to the aroma of beer, was also accomplished using lyophilized cells of R. ruber DSM 44540 in an enantioconvergent enz5miatic step. Inversion at the stereogenic center of (R)-2-methyl-7-octene-2,3-diol,... 

Renwick (S6S) reported on the activity of a number of frontalin analogs in field tests on D. frontalis, the Southern pine beetle. The only analog which showed any additive activity was 5,7-dimethyl-6,8-dioxabicyclo [3.2.1] octane when presented together with frontalin and a-pinene. The 5,7-dimethyl substitution pattern is the same as the 5-methyl-7-ethyl substitution pattern of exo- and encfo-brevicomin. Renwick (363) noted this and also pointed out that while brevicomin is an active component of the attractant of D. brevicomis, it is inactive or suppresses response in D. frontalis. It has since been established that (—)-frontalin is the active enantiomer in this species (46). 

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