928305-66-2Relevant academic research and scientific papers
Internal nucleophilic termination in acid-mediated polyene cyclizations: Part 5. Synthetic access to didehydro analogues of (±)-Ambrox and diastereoisomers
Snowden, Roger L.,Linder, Simon
, p. 3071 - 3086 (2008/01/27)
Treatment of the acyclic tetraenols (E)- and (Z)-2 with an excess of ClSO3H in 2-nitropropane at - 80° stereoselectively afforded in 30 and 43% yield, respectively, diastereoisomer mixtures of the racemic, tricyclic ethers 1c,d and 1a,b, together with 20 (Table). Under identical conditions, but with the acyclic pentaenol 10 (1:1 diastereoisomer mixture) as substrate, the tricyclic ethers 22a/22b (10:1) were isolated in 27% yield. These kinetically controlled stereospecific transformations are thought to proceed via non-concerted pathways (see Schemes 5 and 7), fully consistent with our earlier work. In contrast, another set of reaction conditions (CF 3CO2H, CH2Cl2, -15° to -10°) was used for the cyclization of the monocyclic dienols (E)-3 and (Z)-3, which resulted in the non-stereoselective formation of the major products 1c,d and 1a,b, respectively, in 35-37% yield. Representing novel didehydro analogues of the known ambergris odorant (±)-Ambrox and its diastereoisomers, the qualitative organoleptic properties of 1a-d and of the 10:1 diastereoisomer mixture of the novel tetradehydro analogues 22a/ 22b are briefly described.
