Cis Selective RCM Study to the 14-Membered Cyclic Subunit of Bielschowskysin

Abstract

A concise, (Z)-selective ring-closing metathesis (RCM) route to the 14-membered carbocycle of bielschowskysin is detailed using naturally occurring chiral starting materials. Unproductive RCM substrates were attributed to alkyne chelation of the ruthenium catalyst and steric disadvantages within the cembranoid precursors, which was eventually circumvented by using cyclic diol benzylidene protection involving a C8-quaternary carbinol center.

[2 + 2]-Cycloaddition-derived cyclobutane natural products: structural diversity, sources, bioactivities, and biomimetic syntheses

“…Natural Product Reports summarized the strategies of synthesizing the cyclobutane ring of 284 and reported a concise, (Z)-selective ring-closing metathesis route to the 14-membered carbocycle of bielschowskysin. 287 For these examples, the biomimetic syntheses of [2 + 2] photocycloaddition demonstrated the corresponding biogenetic hypotheses. Alternatively, the [2 + 2] photocycloaddition was used in an attempt to reproduce the biogenetic key steps in the laboratory and to verify biogenetic pathways.…”

“…In 2021, Lear's group summarized the strategies of synthesizing the cyclobutane ring of 284 and reported a concise, ( Z )-selective ring-closing metathesis route to the 14-membered carbocycle of bielschowskysin. 287…”