Stereospezifische Synthese von (+)‐(3 R , 4 R )‐4‐Methyl‐3‐heptanol, das Enantiomere eines Pheromons des kleinen Ulmensplintkäfers ( Scolytus multistriatus )

Stereospecific Synthesis of (+)‐(3 R , 4 R )‐4‐Methyl‐3‐heptanol, the Enantiomer of a Pheromone of the Smaller European Elm Bark Beetle ( Scolytus multistriatus ) Reduction of 2 with actively fermenting baker's yeast gave (−) ‐3. Stereospecific alkylation [3] of (−) ‐3 with propyl iodide furnished ethyl (+)‐(2 R , 3 R )‐2‐propyl‐3‐hydroxypentanoate ((+) ‐4 , 58%) which was converted to the tetrahydropyranyl ether (−) ‐5 , then the alcohol 6 , the p ‐toluenesulfonate 7 and the thiophenyl ether 8 to give the title compound (+) ‐1. The latter consisted of 97% of the threo ‐ and 3% of the erythro ‐isomer. The above synthesis also correlates the absolute configuration of (−)‐( R ) ‐3 with that of (+)‐( R )‐citronellic acid (see [2]).