OAc H H O H O H H (–)-1 (–)-2 3 C O CH 2 Cl CHO H CHO H H 4 5 6 CHO CHO OH OH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 i ii H 6 OH OH 1 2 3 4 5 6 7 8 9 10 11 12 15 i H 7 OH OH O OH H 8 OH OH OH ii iii H O R H O H OH H OAc vi v iv 10 (–)-2 9 R = α-CH 2 OH 11 R = β-CH 2 OH (–)-1 36 J. CHEM. RESEARCH (S), 1998 J. Chem. Research (S), 1998, 36–37† Partial Synthesis of ()-11,12-Dinordriman-8-one and the ()-Enantiomer of Polywood† Manuel Cort´ es,* Luis Moreno and Jos´ e L´ opez Facultad de Qu´ımica, Pontifica Universidad Cat´ olica de Chile, Casilla 306, Correo 22, Santiago, Chile A chiral sequiterpene diol 6, readily available from the natural product polygodial (4), has been used for the first partial synthesis of the title compounds. In a study of the odour evaluation of trans-decalins, the secondary acetate („)-1 and the ketone („)-2 have been reported to possess a woody tonality. 1,2 Racemic 1 (known as Polywood) and 2 have been previ- ously synthesized by acid-catalysed cyclization of acyclic or monocyclic precursors. 3,4 Later, the acetate ()-1 and ketone ()-2 were prepared using enzyme-catalysed kinetic resolu- tion of („)-3. 5 Pursuing our interest in the synthesis of terpe- noids and related products from naturally chiral com- pounds, 6–8 we report here the first partial syntheses of ()-1 and ()-2, using readily available starting material and cheap reagents. The starting material was the chiral diol 6 9–10 derived from isopolygodial (5) which in turn was obtained by basic iso- merization of polygodial (4), available from various natural sources 11–13 (Scheme 1). The synthetic sequence is shown in Scheme 2. Epoxidation of 6 with m-chloroperbenzoic acid produced a single epoxide (7) in 75% yield. the a-stereochemistry of the epoxide was determined by means of both 1 H and 13 C NMR spectroscopy. Comparison of the 7-H signal in the 1 H NMR spectrum of 7 (d 3.3, dd, W 1/2 5.2 Hz) with that of 11-acetoxy- 7a,8-epoxydrimane (d 3.04, dd, W 1/2 4.6 Hz) 14 indicated that both compounds have the same epoxide stereochemistry. On the other hand the signal for C-5, appearing at a field of 15.2 ppm higher than that corresponding to 6 in the 13 C NMR spectrum, confirmed the a configuration of the epoxide as reported for similar compounds. 15 This stereochemistry is explained by considering that the hydrogen bonding between the hydroxy group at C-11 and the peracid directs the epox- idation reactions. 16 The epoxide 7 was refluxed with LiAlH 4 in tetrahydrofuran (THF) to afford the triol 8 in 85% yield. Oxidative degradation of 8 with sodium periodate gave the ketol 9 in 75% yield. Transformation of 9 into ()-2 was carried out by treatment with Jones reagent. The carboxylic acid could not be isolated because decarboxylation was spon- taneous. The retro-aldol process was discarded because when the ketol 9 was treated with a mixture of sulfuric acid, water and acetone (Jones reagent without CrO 3 ), the starting material was recovered exclusively. The physical constants and spectral data of ()-2 were in accord with the values described by Gautier et al. 5 Compound ()-2 was reduced with DIBALH to give the b-alcohol 10 in 80% yield. Finally, acetylation of 10 with Ac 2 O in pyridine gave ()-1 in 97% yield. It is important to note that attempted oxidation of the epimeric ketol 11 (prepared by the same sequence starting with the diol derived from polygodial) gave a large number of products, none of which could be identified. We have no explanation for the difference in reactivity between the two epimers. Experimental Melting points were determined on a Kofler hot-stage apparatus and are uncorrected. Optical rotations were obtained for solutions in chloroform (g/100 mL) on a Perkin Elmer 241 polarimeter. 1 H and 13 C NMR spectra were recorded on a Bruker AM 200 spectro- meter. Chemical shifts are reported in ppm downfield relative to tetramethylsilane (d scale) in CDCl 3 solutions. Carbon substitution degrees were established by DEPT pulse sequence. For analytical TLC, Merck silica gel 60G in 0.25 mm thick layers was used. Chromatographic separations were carried out by conventional column on Merck silica gel 60 (70–230 mesh) using hexane– EtOAc mixtures of increasing polarity. All organic extracts were dried over anhydrous sodium sulfate and evaporated under reduced pressure, below 65 °C. ()-Poly- godial (4) was purified from a light petroleum extract of the bark of Drimys winteri. 11 7a,8-epoxy-(9b-H)-drimane-11,12-diol (7). •To a solution of the diol 6 (1 g, 4.2 mmol) in CH 2 Cl 2 (30 mL) m-chloroperbenzoic acid *To receive any correspondence (e-mail: rmeza@lascar.puc.cl). †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there- fore no corresponding material in J. Chem. Research (M). Scheme 1 Reagents: i, KOH, MeOH (50%); ii, NaBH 4 , MeOH (80%) Scheme 2 Reagents: i, m-chloroperbenzoic acid, CH 2 Cl 2 , 15 °C (75%); ii, LiAlH 4 , THF (85%); iii, NaIO 4 , MeOH (75%); iv, CrO 3 , H 2 SO 4 , acetone (72%); v, DIBALH, THF (80%); vi, Ac 2 O, Py (97%) Published on 01 January 1998. Downloaded on 29/07/2013 02:13:32. View Article Online / Journal Homepage / Table of Contents for this issue