Total Synthesis and Stereochemical Assignment of Delavatine A: Rh-Catalyzed Asymmetric Hydrogenation of Indene-Type Tetrasubstituted Olefins and Kinetic Resolution through Pd-Catalyzed Triflamide-Directed C–H Olefination
Delavatine A (1) is a structurally unusual isoquinoline alkaloid isolated from Incarvillea delavayi. The first and gram-scale total synthesis of 1 was accomplished in 13 steps (the longest linear sequence) from commercially available starting materials. We exploited an isoquinoline construction strategy and developed two reactions, namely Rh-catalyzed asymmetric hydrogenation of indene-type tetrasubstituted
Intramolecular [4 + 3] cycloadditions – Stereochemical issues in the cycloaddition reactions of cyclopentenyl cations – A synthesis of (+)-dactylol
作者:Michael Harmata、Paitoon Rashatasakhon、Charles L Barnes
DOI:10.1139/v06-122
日期:2006.10.1
Five cyclopentanones were prepared for the purpose of examining the effects of stereogenic centers on the course of the intramolecular [4 + 3] cycloaddition reactions of cyclopentenyl cations. One substrate reacted with very high levels of diastereoselectivity and was converted to (+)-dactylol. The cyclopentenone without stereogenic centers on the tether or the five-membered ring gave two cycloadducts
scaffold of this sesterterpenoid. An unprecedented reductive radical 1,6‐addition, mediated by SmI2, forged the cyclobutane motif. Last, a strategic oxidation/reduction step provided not only the decisive solution for the remarkably challenging late‐stage transformations, but also a highly valuable unravelling of the notorious issue of trans‐hydrindane synthesis. Importantly, the synthesis of astellatol
作者:David A. Siler、Jeffrey D. Mighion、Erik J. Sorensen
DOI:10.1002/anie.201402335
日期:2014.5.19
A Robinson annulation, van Leusen homologation, and a desymmetrizing CH oxidation enabled an enantiospecific synthesis of the neurotrophic natural product jiadifenolide. From a pulegone‐derived building block, a key propellane intermediate was constructed through the use of simple reagents in a highly diastereoselective fashion. A short series of oxidations of this tricylic framework allowed progression
Robinson 环化、van Leusen 同源性和去对称 C H 氧化使神经营养性天然产物 jiadifenolide 的对映特异性合成成为可能。通过使用简单的试剂以高度非对映选择性的方式,从胡薄荷酮衍生的构建块中构建了一个关键的推进烷中间体。这种三环骨架的短系列氧化允许发展为天然产物。
Formal Total Synthesis of (−)-Jiadifenolide and Synthetic Studies toward <i>seco</i>-Prezizaane-Type Sesquiterpenes
which culminated in a formal total synthesis of the neurotrophic agent (−)-jiadifenolide. For the construction of the tricyclic core structure, an unusual intramolecular and diastereoselective Nozaki–Hiyama–Kishi reaction involving a ketone as electrophilic coupling partner was developed. In addition, synthetic approaches toward the related natural product (2R)-hydroxy-norneomajucin, featuring a Mn-mediated