A Butyrolactone → 1,3-Diol Strategy for the Obtention ofTolypothrix Polyethers – Stereoselective Synthesis of a Key Lactone Precursor
作者:Henning Priepke、Stefan Weigand、Reinhard Brückner
DOI:10.1002/jlac.199719970804
日期:1997.8
of the key building block syn-9a. This γ-lactone was derived from O-tert-butyldiphenylsilylglycidol (R−15) via a synthetic equivalent of the 6-hydroxy-4-ketoester 12 (cf. Scheme 5). As such, we used the hydroxydiene 28 rather than the 2-(5-hydroxy-3-methylenepentyl)-1,3-oxazoline 26 or the (5-hydroxy-3-methylenepentyl)-substituted orthoester 27 because of its greater ease of preparation (cf. Scheme
一种新型的1,3,5,7,…-多元醇的开发。它遵循-在自然全甲基1,3,5,7,9五醇的合成计划的背景下1A从蓝藻Tolypothrix conglutinata -方案4.本报告关注的对映选择性合成中所描绘的战略关键构建块syn - 9a。该γ-内酯经由6-羟基-4-酮酸酯12的合成当量衍生自O-叔丁基二苯基甲硅烷基缩水甘油(R - 15)(参见方案5)。因此,我们使用羟基二烯28而不是2-(5-羟基-3-亚甲基戊基)-1,3-恶唑啉26或(5-羟基-3-亚甲基戊基)-取代的原酸酯27,因为其更易于制备(参见方案7)。羟基二烯28的双重臭氧分解提供了所需的6-羟基-4-酮酸酯12本身(方案8)。该化合物的CO键减少顺式-选择性(DS = 100:0)通过的Et连续加入2 B(OME)和NaBH 4和抗-选择性(DS = 80:20)通过加入NaBH(OAc)3(方案9)。在上述syn中形成的二羟基酯syn