Trypodendron Lineatin

The synthesis of lineatin, a pheromone of the insect Trypodendron lineatum, involves the enantioselective addition of methane to the double bond of alkene A in the presence of a chiral rhenium catalyst on silica (Re /silica see Figure 2.19). Michael performed eight separate experiments for this reaction in a 500 mL high-pressure stirred autoclave reactor using liquid methane as a solvent and 0.05 mmol catalyst. The results are shown in Table 2.2. 

Borden J. H., Oehlschlager A. C., Chong L., Slessor K. N. and Pierce H. D., Jr, (1980a) Field tests of isomers of lineatin, the aggregation pheromone of Trypodendron lineatum (Coleoptera Scolytidae). Can. Entomol. 112, 107-109. 

Hoover S. E. R., Lindgren B. S., Keeling C. I. and Slessor K. N. (2000) Enantiomer preference of Trypodendron lineatum and the effect of pheromone dose and trap length on response to lineatin-baited traps in interior British Columbia../. Chem. Ecol. 26, 667-677. 

MacConnell J. G., Borden J. H., Silverstein R.M. and Stokkink E. (1977) Isolation and tentative identification of lineatin, a pheromone from the frass of Trypodendron lineatum (Coleoptera Scolytidae). J. Chem. Ecol. 3, 549-561. 

The enantiomeric composition of lineatin in Trypodendron lineatum was not determined, but the synthesized (racemic) material was highly active in field tests (13,14). Mori et al. (Scheme 4) (13) and Slessor et al. (Scheme 5) (16) synthesized the lineatin enantiomers and reported similar optical purities, but because different solvents were used, the optical rotations cannot be compared. Since the (+) enantiomer was active in field tests (16), we may assume that it is the naturally occurring enantiomer however the presence of the antipode cannot be ruled out. 

Most of the new synthetic work on cyclobutane monoterpenoids concerns the insect pheromone (+ )-grandisol (295) (Vol. 2, p. 58 Vol. 4, p. 488) and (+ )-lineatin (296), a pheromone of the Douglas fir beetle, Trypodendron lineatum (Vol. 4, p. 489, Ref. 255). There are, however, two other syntheses described, and these will be dealt with first. 

Cyclobutane.—A tricyclic acetal named lineatin has been isolated from the frass of the Douglas fir beetle Trypodendron lineatum structural elucidation and synthesis have not distinguished between (104) and (105). ... 

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