English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A stereogenic center, placed at an exocyclic location next to a chiral carbon in a ring to which it is attached, is a ubiquitous structural motif seen in many bioactive natural products, including di- and triterpenes and steroids. Installation of these centers has been a long-standing problem in organic chemistry. Few classes of compounds illustrate this problem better than serrulatanes and amphilectanes, which carry multiple methyl-bearing exocyclic chiral centers. Nickel-catalyzed asymmetric hydrovinylation (AHV) of vinylarenes and 1,3-dienes such as 1-vinylcycloalkenes provides an exceptionally facile way of introducing these chiral centers. This Article documents our efforts to demonstrate the generality of AHV to access not only the natural products but also their various diastereoisomeric derivatives. Key to success here is the availability of highly tunable phosphoramidite Ni(II) complexes useful for overcoming the inherent selectivity of the chiral intermediates. The yields for hydrovinylation (HV) reactions are excellent, and selectivities are in the range of 92-99% for the desired isomers. Discovery of novel, configurationally fluxional, yet sterically less demanding 2,2'-biphenol-derived phosphoramidite Ni complexes (fully characterized by X-ray) turned out to be critical for success in several HV reactions. We also report a less spectacular yet equally important role of solvents in a metal-ammonia reduction for the installation of a key benzylic chiral center. Starting with simple oxygenated styrene derivatives, we iteratively install the various exocyclic chiral centers present in typical serrulatane [e.g., a (+)- p-benzoquinone natural product, elisabethadione, nor-elisabethadione, helioporin D, a known advanced intermediate for the synthesis of colombiasin and elisapterosin] and amphilectane [e.g., A-F, G-J, and K,L pseudopterosins] derivatives. A concise table showing various synthetic approaches to these molecules is included in the Supporting Information. Our attempts to synthesize a hitherto elusive target, elisabethin A, led to a stereoselective, biomimetic route to pseudopterosin A-F aglycones.

journal of the american chemical society

Broadly Applicable Stereoselective Syntheses of Serrulatane, Amphilectane Diterpenes, and Their Diastereoisomeric Congeners Using Asymmetric Hydrovinylation for Absolute Stereochemical Control