Musk or violet? Design, synthesis and odor of seco-derivates of a musky carotol lead

By a six-step synthetic route consisting of a Li₂MnCl₄-catalyzed coupling of branched alkyl magnesium chlorides with isovaleryl and 3,3-dimethylbutanoyl chloride, Grignard reaction of the product with ethynyl magnesium bromide, dehydration and transformation into a Grignard reagent, subsequent reaction with acetaldehyde, (E)-selective hydrogenation of the alkynol triple bond with lithium aluminum hydride, and finally pyridinium chlorochromate oxidation, four sterically highly demanding target structures were synthesized diastereoselectively. These four molecular targets were designed as seco-structures to a musky carotol lead, and their olfactory profiles that merge violet like with musky notes to different extents, provide interesting insight into structure–odor correlation.