Syntheses in the Isocamphane Series, XVII. Isocamphanyl-γ-butyrolactone, a New Compound with a Sandalwood Odour

Article abstract of DOI:10.1007/BF00899785

The synthesis of a new compound with a sandalwood odour is described.The synthesis of the lactone 1 has been designed by molecular considerations: a bicyclus with a side chain containing 5-7 carbon atoms and an oxygene containing osmophoric group.One route to synthesize 1 leads from the ketone 3 via the Mannich base 4 to the γ-ketonitrile 6 which after hydrolysis to the γ-keto acid 7 and reduction of the latter cyclises spontaneously to 1.A shorter route starts from the α-bromoketone 13 which could be transformed by malonic ester synthesis into 7.Other synthetic routes, e.g. cyanoethylation to the homologous δ-lactone 16, aldol condensation, alkylation, carboxymethylation and carboxyethylation of 3 failed as well as the preparation of the oxazoline protected 3-bromopropionic acid for a Grignard synthesis with 3. 1 exhibits a sweed, warm odour of sandalwood with an interesting note of cedarwood. - Keywords: Cyanoethylation; γ-Keto acid; γ-Ketonitrile; γ-Lactone; Malonic ester synthesis; Mannich reaction; Oxazoline protecting group