Synthesis of Enantiomerically Pure 1,7-Dioxaspiro[5.5]undecanes, Pheromone Components of the Olive Fly (Dacus oleae)

✍ Scribed by Priv.-Doz. Dr Hartmut Redlich; Priv.-Doz. Dr Wittko Francke

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 262 KB
• Volume: 23
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198405191

✦ Synopsis

On reduction with NaBH4 in methanol (or 2-propanol) or LiAlH4 in tetrahydrofuran (THF), the 2-acylindoles 1 are converted into the 2-( 1-hydroxyalky1)indole derivatives 2. The 2-(3-dimethylaminopropionyl)indoles l c and Id are obtained from the 2-acetylindoles laL3] and lbI4], respectively, by Mannich reaction with formaldehyde and dimethylamine. Reaction of 2 with DEAD/Ph3P (molar ratio 1 : 1) in THF leads, in all cases, to crystalline products, which, according to elemental analyses, contain 1 mol of incorporated DEAD. Even addition of nucleophiles (e. g. phenol) did not lead to the substitution products to be expected in a Mitsunobu reaction. 'H-NMR, IR, and mass spectroscopic data (Table 1) showed that a cycloaddition to give ethyl 1 -alkyl-4-ethoxy-1,2-dihydro[1,2,4]triazino[4,5-a]indole-2-carboxylates 3 takes place. These can be converted by treatment with acid into the ethyl l-alkyl-1,2,3,4-tetrahydr0-4-0~0[ 1,2,4]triazino[4,5-a]indole-2-carboxylates 4.