302 JOURNAL OF COSMETIC SCIENCE 18, R = Ac c /Si•oR dE17 ,R=H 19, R Ac a) 1. nBu-Li, Et.20 , _ 78 o C, 2. CISi(CH3)2CH=CH 2 , Et.20 b) MCPBA c) DIBAL d) AcCI, Py Scheme 3 (yield 79%) was the one-step reduction of epoxide 15 with two equivalents of diisobu- tyloaluminum hydride, which led directly to 17. Acetates 4, 9, 13, 18, and 19 were obtained in good yield (60-90%) by esterification of corresponding alcohols 3, 8, 12, 16, and 17 with acetyl chloride in the presence of anhydrous pyridine. The odor characteristics of the compounds obtained are given in Table I. Comparison of the odors of carbon compounds and their silicon analogues indicates that the odors of carbon compounds are more intensive and more fresh than silicon ones. The odors of carbon alcohols can be generally described as fresh-green, whereas sila alcohols are described as floral-fruity or fruity. Acetates, with the exception of 19, are characterized by a fruity or a fruity-floral odor. The comparative olfactory analysis of compounds with different geometry of the double bond shows differences in notes of odors. The most distinctive difference was observed for E and Z isomers of sila acetates (13 and 19). Alcohol with a triple C-C bond is characterized by the most floral odor among the compounds evaluated. EXPERIMENTAL STARTING MATERIALS AND REAGENTS 4-Methyl-l-pentyne (b.p. 61-62øC lit. (13) 61øC) was synthesized from 4-methyl-i-

3,3,7-TRIMETHYL-4-OCTEN-1-OLS 303 Table I Odor Descriptions of Compounds Synthesized* Compound - OH - OC(O)CH 3 Medium-intensive, fresh- green, fioral-fruity, with rose and grapefruit notes Intensive, more than E isomer, agreeable, fresh-green, with tomato leaf and citrus notes Weak, agreeable, floral- fruity Medium-intensive, less than C analogue, fresh, fruity, with melon fruit note Weak, agreeable, floral- fruity, with lime flower note Intensive, agreeable, fruity, with apricot note Medium-intensive, fresh, fruity, with desiccated- apricot note Weak, fruity, with wild strawberry note Medium-intensive, agreeable, fresh, balsamic-vegetable note Weak, agreeable, fresh, fruity-fioral * The odor was evaluated for samples that were above 97% (gc) purity. pentene by bromination followed by elimination of 1,2-dibromide with potassium hydroxide. All other reagents used in this work were purchased from Fluka. ANALYTICAL METHODS 1H NMR spectra were measured for solutions (CDC13) on Bruker Avance DRX 300 (300 MHz). IR spectra were determined with a Specord M-80 infrared spectrophotometer. Gas chromatographic analyses were performed on a Hewlett-Packard instrument, using an HP-5 capillary column (30 m x 0.31 mm). Analytical TLC was carried out on silica gel G (Merck) with different developing systems. Compounds were detected by spraying the plates with 7 % H2SO 4 in ethanol containing ca 0.1% of p-anisaldehyde, followed by heating to 120øC. Column chromatography was performed on silica gel (Kieselgel 60, 230-400 mesh, Merck) with petroleum ether-ethyl acetate 7:1 (for alcohols) or 50:1 (for esters) systems as eluents. OLFACTORY EVALUATION Odorous properties of the compounds synthesized were determined by Prof. J. G6ra strictly following the described procedure (14).