Total Synthesis of (±)-Cephanolides B and C via a Palladium-Catalyzed Cascade Cyclization and Late-Stage sp3 C–H Bond Oxidation

2018 ◽  
Vol 140 (16) ◽  
pp. 5653-5658 ◽  
Author(s):  
Lun Xu ◽  
Chao Wang ◽  
Ziwei Gao ◽  
Yu-Ming Zhao

2019 ◽  
Vol 17 (14) ◽  
pp. 3552-3566 ◽  
Author(s):  
Ranjan Kumar Acharyya ◽  
Pratik Pal ◽  
Shrestha Chatterjee ◽  
Samik Nanda

An efficient asymmetric total synthesis of naturally occurring γ-Z-butenolide cryptoconcatone I was achieved by employing substrate-directed reductive epoxide ring opening and late-stage “Pd–Cu” catalyzed cascade cyclization.



2021 ◽  
Author(s):  
Kristen Flynn ◽  
Kolby White ◽  
Mohammad Movassaghi

We describe a palladium catalyzed C7-acetoxylation of indolines with a range of amide directing groups. While a variety of substituents are tolerated on the indoline-core and the N1-acyl group, the acetoxylation is most sensitive to the C2- and C6-indoline substituents. The practicality of this indoline C7-acetoxylation is demonstrated using a cinnamamide substrate on mmol-scale. Several N1-acyl groups, including those present in natural alkaloids, guide C7-acetoxylation of indoline substrates over a competitive C5-oxidation. The application of this chemistry allowed for the first synthesis of N-benzoylcylindrocarine by late-stage C17-acetoxylation of N-benzoylfendleridine.



2019 ◽  
Author(s):  
Timothy Newhouse ◽  
Aneta Turlik ◽  
Yifeng Chen ◽  
Anthony Scruse

<div> <p>The total synthesis of principinol D, a rearranged kaurane diterpenoid, is reported. This grayanane natural product is constructed via a convergent fragment coupling approach, wherein the central 7-membered ring is synthesized at a late stage. The bicyclo[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction. Strategic reductions include a diastereoselective SmI<sub>2</sub>-mediated ketone reduction with PhSH and a new protocol for selective ester reduction in the presence of ketones. The convergent strategy reported herein may be an entry point to the larger class of kaurane diterpenoids.</p> </div>



2019 ◽  
Author(s):  
Nicolas Duchemin ◽  
Roberto Buccafusca ◽  
Marc Daumas ◽  
Vincent Ferey ◽  
Stellios Arseniyadis

We report here a general method that allows a highly straightforward access to tertiary difluoromethylated compounds. The strategy relies on a two-step sequence featuring a C-selective electrophilic difluoromethylation and an unprecedented palladium-catalyzed decarboxylative protonation. Considering the generality of the method and the attractive properties offered by the difluoromethyl group, this approach provides a valuable tool for late-stage functionalization and drug development.<br>



2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>



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