Synthesis of (±)warburganal

The Diels–Alder route to drimane related sesquiterpenes; synthesis of cinnamolide, polygodial, isodrimeninol, drimenin and warburganal

“…82. 5 78-79 " C ; v,,,~,,, 1 8) (1 g, 3.4 mmol) was dissolved in methanol (500 ml) containing concentrated hydrochloric acid (0.25 ml); 10% Pd/C (100 mg) was added to the solution and the mixture then hydrogenated at atmospheric pressure in the usual way. The reaction was monitored by g.1.c.…”

“…The concept of using the Diels-Alder reaction in drimane natural product synthesis is not new and was first used by Brieger in his synthesis of winterin. Improvements to the initial Diels-Alder process were later introduced by Campos ' and lo perf id^.^ We 43 and others have also exploited this approach to drimane sesquiterpene synthesis and here report in full o n the preparation of five members of this group of compounds, namely cinnamolide (l), polygodial (2), isodrimeninol (3), drimenin (4), and warburganal (5).…”

“…Hydroxylating organisms are well known and have been used extensively.28 The chemical yields in these processes are often mediocre to poor, however, we felt that the potential reward more than justified their investigation. While these microbial oxidations also failed to provide warburganal (5) from (2) interesting and potentially very useful reactions were discovered which are discussed here. Hence incubation of polygodial together with Cicnnitrghamella eleguns, a known allylic hydroxylating organism,29 for 10 days gave on work-up a single product in a remarkable 90% yield.…”

Drimenol: A Versatile Synthon for Compounds with trans-Drimane Skeleton

“…This semisynthetic approach starting from (-)-drimenol was performed in twelve steps with an overall yield of 10% (Figure 21). After the report by Ley et al [32] of the direct conversion of (±)-drim-7-ene-9,11,12-triol ( 61) to (±)-warburganal (57), Cortes et al [31] prepared chiral triol 61 from (-)-drimenol (1), which supposed a formal synthesis of warburganal (57). Acetylation of natural 1, afforded drimenyl acetate (4), in 97% yield.…”

Structure of (1S,6S,8S,9S,1'S)-8-(1'-hydroxyethyl)-9-hydroxymethyl-1,5,5-trimethylbicyclo[4.3.0]nonane

“…Drimenol (1) is a sesquiterpenic alcohol isolated from Drymis winteri Forst (Appel, Brooks & Overton, 1959). As part of a systematic study of molecule (1) in order to obtain derivatives of interest in pharmacology (Ley & Mahon, 1981) and perfumery (Brunke, 1980), the tosylated molecule (2) has been synthesized (Planas, Cort6s & Bonet, 1985). The reduction of (2) with LiAlH 4 gives a product (35% CtsH28Oz yield) whose complete structure could not be elucidated.…”