Synthetic studies aimed at the elucidation of the stereostructure of the aggregation pheromone, 2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol, produced by the male stink bug Erysarcoris lewisi

The male-produced aggregation pheromone of the stink bug Erysarcoris lewisi Distant was shown to be one of the two diastereomers of (2Z,6R)-2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol by synthesizing and bioassaying (2E,6R)-, (2E,6S)-, (2Z,6R)-, and (2Z,6S)-isomers. These were synthesized from the enantiomers of citronellal by employing an intramolecular α-ketocarbene addition to a double bond and the E-selective or Z-selective olefination of a formyl group as the key steps. A reliable method was developed for the preparation of ethyl 2-(di-o-tolylphosphono)propanoate, Ando’s reagent for Z-selective olefination.

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(R)-3,7-Dimethyl-2-methylene-6-octenalC11H18O[α]D24=-13.6 (c 3.45, hexane)Source of chirality: (R)-citronellalAbsolute configuration: (R)

(S)-3,7-Dimethyl-2-methylene-6-octenalC11H18O[α]D24=+13.1 (c 4.72, hexane)Source of chirality: (S)-citronellalAbsolute configuration: (S)

(R)-3,7-Dimethyl-2-methylene-6-octen-1-olC11H20O[α]D25=-19.4 (c 4.50, hexane)Source of chirality: (R)-citronellalAbsolute configuration: (R)

(S)-3,7-Dimethyl-2-methylene-6-octen-1-olC11H20O[α]D22=+19.0 (c 4.19, hexane)Source of chirality: (S)-citronellalAbsolute configuration: (S)

Ethyl (R)-5,9-dimethyl-4-methylene-8-decenoateC15H26O2[α]D21=-11.6 (c 4.85, hexane)Source of chirality: (R)-citronellalAbsolute configuration: (R)

Ethyl (S)-5,9-dimethyl-4-methylene-8-decenoateC15H26O2[α]D24=+11.5 (c 5.03, hexane)Source of chirality: (S)-citronellalAbsolute configuration: (S)

(R)-5,9-Dimethyl-4-methylene-8-decenoic acidC13H22O2[α]D23=-14.0 (c 4.41, hexane)Source of chirality: (R)-citronellalAbsolute configuration: (R)

(S)-5,9-Dimethyl-4-methylene-8-decenoic acidC13H22O2[α]D23=+13.9 (c 4.28, hexane)Source of chirality: (S)-citronellalAbsolute configuration: (S)