Total Synthesis of Leiodermatolide A via Transfer Hydrogenative Allylation, Crotylation, and Propargylation: Polyketide Construction beyond Discrete Allyl- or Allenylmetal Reagents
作者:Yuk-Ming Siu、James Roane、Michael J. Krische
DOI:10.1021/jacs.1c06062
日期:2021.7.21
The totalsynthesis of leiodermatolide A was accomplished in 13 steps (LLS). Transfer hydrogenative variants of three carbonyl additions that traditionally rely on premetalated reagents (allylation, crotylation, and propargylation) are deployed together in one totalsynthesis.
leiodermatolide A 的全合成分 13 个步骤 (LLS) 完成。传统上依赖于预金属化试剂(烯丙基化、巴豆酰化和炔丙基化)的三种羰基加成的转移氢化变体在一个全合成中一起部署。
Stereoselective synthesis of polyketide fragments using a novel intramolecular Claisen-like condensation/reduction sequence
Claisen-type cleavage of the Evans-oxazolidinone with an acetateenolate followed by reduction of the resulting ketone using a borane–amine complex yielded β-hydroxy-δ-lactones as fully functionalized polyketide precursors stereoselectively. Consequently, this reaction sequence constitutes a highlypractical alternative to an acetate–aldol reaction.
Subtle but distinctive: The stereostructure of the biologically highly promising antimitoticagentleiodermatolide was uncertain. A short, efficient, and flexible totalsynthesis based on ring‐closing alkyne metathesis as the key step has now solved the puzzle. Subtle differences in the 1H NMR spectra of the structure shown and the conceivable isomer proved invaluable for the assignment.
微妙但与众不同:生物学上很有前途的抗有丝分裂剂leiodermatolide的立体结构尚不确定。以开环炔烃复分解为关键步骤的短而有效且灵活的全合成方法现已解决了这个难题。所示结构和可能的异构体在1 H NMR光谱中的细微差异证明对于该赋值是无价的。