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subunits of the aglycone have been described by Cuevas and by Ciufolini. Highlights of these contributions are outlined below.
Cuevas’s cyclopentane analog
Modeling studies by Cuevas et al. relying on the INSIGHT software [43][44] reduced the tetracyclic framework of sordarin to a simple cyclopentane
derivative 62 (Scheme 12), which contains aldehyde, carboxylic acid and hydroxymethyl groups as pharmacophores. The dihedral angles of CHO-CH2-CH2-COOH in the cyclopentane analog are very close to those of the carbon skeleton in sordaricin.
The synthesis of 62 started with commercially available (+)-3,9
compared to sordaricin (2) the cyclopentane analogs showed generally reduced potency towards a C. albicans protein synthesis assay, as well as diminished suppression of C. albicans cell growth, some analogs were actually more potent in certain tests. For instance, analogs 74, 78, 83 were all more potent
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oxocompounds provides an easy entry to the synthesis of oxoallylsilanes 3–8 which are useful synthons for cyclopentane annulations (Scheme 2). [7][9] Acid chlorides react with 2 affording divinyl ketones 9–10.
Allylsilanes 3–8 carrying an electrophilic carbonyl moiety readily undergo intramolecular cyclization
-1-ones 15–16 (Scheme 3), which are not easily prepared by classical methods, and for which few methods of synthesis have been reported in the literature. [7][13]
Silylcupration of acetylenes is also a powerful tool for cyclopentane annulations. Terminal alkynes 17–19 bearing electron-withdrawing