Total Synthesis of Ascospiroketal A Through a Ag
<sup>I</sup>
‐Promoted Cyclization Cascade
作者:Stanley Chang、Soo Hur、Robert Britton
DOI:10.1002/anie.201408905
日期:2015.1.2
The totalsynthesis of four candidate stereostructures for the marine octaketide ascospiroketal A have been achieved. These concise and highly stereocontrolled syntheses feature a unique AgI‐promotedcyclizationcascade involving an oxetanyl ketochlorohydrin to access the entire tricyclic core of the natural product in one step. These syntheses also establish the full stereochemistry for the ascospiroketal
Asymmetric Total Syntheses of <i>ent</i>-Ascospiroketals A and B
作者:Jian Wang、Rongbiao Tong
DOI:10.1021/acs.orglett.6b00796
日期:2016.4.15
A new hypothetic biosynthesis of the tricyclic spiroketal core of ascospiroketals A and B is proposed, which guided the development of a novel synthetic strategy for the asymmetric totalsynthesis of ent-ascospiroketals A and B. The synthesis features an efficient ring contraction rearrangement of the 10-membered lactone to the tricyclic spiroketal cis-fused γ-lactone core, which served as the common
提出了一种新的假生物合成方法,即合成螺帽动物A和螺帽B的三环螺帽动物核心,它指导了新的合成策略,用于合成不对称的对映体螺帽动物A和螺帽B。该合成具有有效的10位环收缩重排的特点。成员内酯形成三环螺旋酮体顺式融合的γ-内酯核,这是最后一步通过Stille偶联反应合成对乙酰氨基酮体A和B的通用中间体。另外,7个非对映体准备决定性确认的结构耳鼻喉科-ascospiroketal B.
Ascospiroketal B was isolated from a marine-derived fungus as a structurally unique polyketide possessing a rare tricyclic core including 5,5-spiroketal-γ-lactone. An asymmetric totalsynthesis of ent-ascospiroketal B was achieved using an original synthetic route. The synthesis included the stereoselective construction of 5,5-spiroketal for ascospiroketal B and stereocontrolled construction of a quaternary