ISSN:
0018-019X
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Reaction of the triolide 1 from (R)-3-hydroxybutanoic acid with Lawesson's reagent 5 leads to the mono-, di-, and trithio derivatives 6-8 which can be isolated in pure form (20-40% yields), and which have crystal structures very similar to the parent triolide 1 (Fig. 1). Similarly, pentolide 3 is converted to mixtures of various thio derivatives, three of which are separated (10-12) by HPLC and fully characterized. The X-ray structures of the mono- and of one of the dithiopentolides (10, 12) differ remarkably from each other (Fig. 3). Reduction of the thiotriolides 6-8 (NaBH4, R3SnH, Cl3SiH, Raney-Ni) gives 12-membered rings containing up to three ether groups (chiral crown ethers, 15, 17-19) in poor yields. The thiotriolides react spontaneously and in yields of up to 96% with ammonia, certain primary amines, and hydroxylamine to give imine and oxime derivatives with intact 12-membered-ring backbones (20, 22-24, 30, see crystal structures in Figs. 4-7). The rigid structure of all the derivatives of triolide 1 puts the C=O, C=S, and C=NR O-, S-, and N-atoms in juxtaposition (a feature reminiscent of the side chains in the iron-binder enterobactin, Fig. 6). Imines containing PPh2 groups are prepared (30, 33, 35) from the thiotriolides and tested as chiral ligands for PdII-catalyzed 1,3-diphenyallylations (→ 37, enantiomer ratio up to 77:23). The reactions described demonstrate that multiple reactions of the triolide 1 from (R)-3-hydroxybutanoic acid which proceed through tetrahedral intermediates are possible without ring opening - the skeleton is remarkably stable, and this might be exploited as a template for bringing up to three pendent substituents into close proximity to allow a study of their interactions and cooperative properties. Also, the di- and trithio derivatives 7 and 8 could be used for cross-linking in molecules containing primary NH2 groups.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/hlca.19960790202
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