Secondary metabolites by chemical screening -13. Enantioselective synthesis of δ-lactones from streptenola, achiral building block from streptomyces
摘要:
The enantioselective synthesis of all four stereoisomers of the secondary metabolite 3-hydroxy-5-decanolide (4a) from Cephalosporium recifei and both enantiomers of massoialactone (5a) by starting from one chiral building block, streptenol A (1a), a secondary metabolite from Streptomyces sp., is described. The key steps of the reaction sequence involve diastereoselective reduction of 1a to syn- or anti-triol 2a and 2b and the regioselective oxidation of the primary hydroxyl group. This reaction furnishes in one step the sigma-lactones 3a and 3b and requires no protecting group.
Secondary metabolites by chemical screening -13. Enantioselective synthesis of δ-lactones from streptenola, achiral building block from streptomyces
摘要:
The enantioselective synthesis of all four stereoisomers of the secondary metabolite 3-hydroxy-5-decanolide (4a) from Cephalosporium recifei and both enantiomers of massoialactone (5a) by starting from one chiral building block, streptenol A (1a), a secondary metabolite from Streptomyces sp., is described. The key steps of the reaction sequence involve diastereoselective reduction of 1a to syn- or anti-triol 2a and 2b and the regioselective oxidation of the primary hydroxyl group. This reaction furnishes in one step the sigma-lactones 3a and 3b and requires no protecting group.
Synthesis of (−)-Streptenol A, (±)-Streptenol B, C and D
作者:Siegfried Blechert、Heribert Dollt
DOI:10.1002/jlac.199619961228
日期:1996.12
3-dioxan-4-yl)acetaldehyde (3) was used for the preparation of streptenol A and B (Scheme 1) via a Grignard reaction with 1-bromopent-3-ene. Hereby optically pure (4′R)-3 gave the antipode of Streptenol A. Reaction with lithiated 1-pentyne opened access to streptenol C and D. To obtain the dienone structure of streptenol C and D, a palladium-catalyzed alkynone isomerization was induced. Kinetic differences
通过与1-溴戊-3-烯的格氏反应,使用2-(2,2-二甲基-1,3-二恶烷-4-基)乙醛(3)制备链烯醇A和B(方案1)。特此光学纯(4' - [R )- 3,得到Streptenol A.反应的对映体与锂化的1-戊炔打开访问streptenol C和D为获得streptenol C和d的二烯酮结构,钯催化的炔酮异构化诱导。1,3-丙酮化物保护的1,3,5-三醇系统在酸介导的裂解中的动力学差异导致了天然产物的立体选择性。所以只有(3 S *,5 R *)链烯醇B的丙酮化物在温和的水解条件下反应,并在缩醛化后首先提供具有相对相对立体化学的3,5-保护的链烯醇B,最后是(3 S *,5 R *)-链烯醇B.
Process for the stereoselective preparation of 5-substituted
申请人:Hoechst Aktiengesellschaft
公开号:US05292898A1
公开(公告)日:1994-03-08
A process for the stereoselective preparation of 5-substituted .delta.-lactones of the formulae Ia, Ib, Ic and Id ##STR1## in which R.sup.1 is a straight-chain or branched alkyl or alkenyl group or methylhydroxy, novel 5-substituted .delta.-lactones and novel intermediates, and use thereof as pharmaceuticals having cholesterol synthesis-inhibiting action, fragrances and flavorings is described.
Verfahren zur stereoselektiven Herstellung von 5-substituierten delta-Lactonen und deren Verwendung
申请人:HOECHST AKTIENGESELLSCHAFT
公开号:EP0469480A2
公开(公告)日:1992-02-05
Es wird ein Verfahren zur stereoselektiven Herstellung von 5-substituierten 8-Lactonen der Formeln Ia, Ib, Ic und Id
wobei R1 für geradkettige oder verzweigte Alkyl- oder Alkenylgruppe oder für Methylhydroxy steht, neue 5-substituierte δ-Lactone und neue Zwischenprodukte, sowie deren Verwendung als Arzneimittel mit Cholesterin-Synthese hemmender Wirkung, Duft- und Geschmackstoffe, beschrieben.