Stereoselective synthesis of (3S,5S,6S)-tetrahydro-6-isopropyl-3,5-dimethylpyran-2-one; a C5-epimer of a component of a natural sex pheromone of the wasp Macrocentrus grandii, the larval parasitoid of the European corn borer Ostrinia nubilalis

(3S,5S,6S)-Tetrahydro-6-isopropyl-3,5-dimethylpyran-2-one, a C5-epimer of a component of the natural sex pheromone of the wasp Macrocentrus grandii, the larval parasitoid of the European corn borer Ostrinia nubilalis, was synthesized starting from methyl l-valinate. The transformation includes a Kulinkovich cyclopropanation reaction, a cationic cyclopropyl-allyl rearrangement of cyclopropyl methanesulfonate, a diastereoselective alkylation of Oppolzer’s (N-propionyl)-(2R)-bornane-10,2-sultam and a diastereoselective hydrogenation using Wilkinson’s catalyst as the key steps.

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(S)-2-(Bromomethyl)-4-methylpent-1-en-3-olC7H13BrO[α]D = +13.7 (c 2.73, CHCl3)Absolute configuration: (S)Source of chirality: l-valine (chiral substrate)

(3S)-2-[(2S)-3-(8,8-Dimethyl-2,2-dioxidotetrahydro-3a,6-methano-2,1-benzisothiazol-1(4H)-yl)-2-methyl-3-oxopropyl]-4-methylpent-1-en-3-olC20H33NO4S[α]D = −6.9 (c 2.70, CHCl3)Absolute configuration: (3S,2S)Source of chirality: Oppolzer’s sultam

(3S,4S,6S)-7-(8,8-Dimethyl-2,2-dioxidotetrahydro-3a,6-methano-2,1-benzisothiazol-1(4H)-yl)-2,4,6-trimethyl-7-oxoheptan-3-olC20H35NO4S[α]D = −8.8 (c 2.22, CHCl3)Absolute configuration: (3S,4S,6S)Source of chirality: asymmetric synthesis

(3S,6S)-Tetrahydro-6-isopropyl-3-methyl-5-methylenepyran-2-oneC10H16O2[α]D = +34.1 (c 2.32, CHCl3)Absolute configuration: (3S,6S)Source of chirality: asymmetric synthesis

(3S,5S,6S)-Tetrahydro-6-isopropyl-3,5-dimethylpyran-2-oneC10H18O2[α]D = −11.4 (c 2.18, CHCl3)Absolute configuration: (3S,5S,6S)Source of chirality: asymmetric synthesis