Asymmetric Tandem Additions
to Chiral 2,3-Dihydronaphthyloxazolines: Synthesis of the Triptoquinone/Triptinin
A Ring System
作者:A. Meyers、Laura Basil、Hiroto Nakano、Rogelio Frutos、Michael Kopach
DOI:10.1055/s-2002-34373
日期:——
A study to reach the diterpenoid (+)-triptoquinone A (3) or its analog (+)-triptinin A (4) via an asymmetric tandem addition to naphthyloxazolines is described. The tandem addition to the chiral dihydronophthalene 6 resulted in a 70% yield of a single diastereomer 10. Further manipulation gave the natural products’ tricyclic ring system, compounds 20 and 29 via ring-closing metathesis in 90% yield, using the Schrock catalyst. Final assault to the target compounds 3 or 4 fell short due to the failure to either reduce a neopentyl hydroxymethyl group to a methyl or to install the conjugated carboxylic acid present in 3 or 4.
描述了一项研究,旨在通过不对称串联加成反应合成二萜类化合物(+)-triptoquinone A(3)或其类似物(+)-triptinin A(4),该反应以萘基苯并噁唑啉为基础。对手性二氢萘烷6的串联加成反应获得了70%产率的单一非对映异构体10。进一步操作通过环闭合插值反应,将天然产物的三环结构合成到化合物20和29,产率达到90%,使用的是Schrock催化剂。然而,最终合成目标化合物3或4未能成功,原因在于无法将新戊基羟甲基基团还原为甲基,或者无法引入存在于3或4中的共轭羧酸。