Syntheses, Structures, and Sensory Characteristics of the Perfume Ingredient Majantol and Its Analogs Sila-majantol and Germa-majantol:  A Study on C/Si/Ge Bioisosterism§

The perfume ingredient majantol [2,2-dimethyl-3-(3-methylphenyl)propan-1-ol (1a)] and its silicon- and germanium-containing analogs sila-majantol [(hydroxymethyl)dimethyl(3-methylbenzyl)silane (1b)] and germa-majantol [(hydroxymethyl)dimethyl(3-methylbenzyl)germane (1c)], respectively, were synthesized from i-PrC(O)Ph (four steps, → 1a), Me2Si(CH2Cl)Cl (three steps, → 1b), or Cl3GeCH2Cl (four steps, → 1c). The structures of the C/Si/Ge analogs 1a/1b/1c were determined by crystal structure analyses and computational studies [RI-MP2 calculations (TZVP level)]. The odor of majantol (1a) was found to be strong fresh-floral, aqueous-aldehydic, and characteristic of lily-of-the-valley flowers, whereas that of sila-majantol (1b) was considerably less intense than that of 1a. It lacked the aqueous-aldehydic freshness, but possessed nevertheless the characteristic lily-of-the-valley odor, but it was more terpineol-like. The odor of germa-majantol (1c) was very weak and not characteristic; the majantol impression could be recognized only as a shade.