Efficient palladium-mediated synthesis of a spirocyclic model for fredericamycin A.

Efficient Synthesis of Optically Active Atropisomeric Anilides through Catalytic Asymmetric N-Arylation Reaction

“…Melting points were uncorrected. 1 H and 13 C NMR spectra were recorded on a 300 MHz spectrometer. In 1 H and 13 C NMR spectra, chemical shifts were expressed in δ (ppm) downfield from CHCl 3 (7.26 ppm) and CDCl 3 (77.0 ppm), respectively.…”

Synthetic Approaches to the Anticancer Agent Fredericamycin A

“…Recently in 2019, Kotha and co‐workers designed the ABCD ring system of fredericamycin A by adopting a double‐Claisen rearrangement and ring‐closing metathesis (RCM) as key steps [7i] . This strategy is somewhat unique since the quaternary spirocyclic centre is created by allylation and RCM protocol for the first time.…”

“… Claisen rearrangement and ring‐closing metathesis approach to the ABCD core of fredericamycin A 1 (Kotha and co‐workers) [7i] …”

Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

“…The aldehyde underwent tandem addition of the anion of simple phthalide (a model for 20 ; prepared from the parent compound by deprotonation with LDA) and dehydration via mesylate 26 to provide 27 , which upon reaction with EtOLi (EtOH + BuLi) in THF rearranged to diketone 28 . Experiments involving 28 , as well as simpler model systems [ 38 ], revealed that the few techniques of enolate arylation then known were completely ineffective for the desired transformation. Remarkably, however, heating a DMF solution of the preformed sodium enolate of 28 (NaH) in the presence of Pd(PPh 3 ) 4 triggered cyclization to 29 in a very satisfactory 76% yield [ 39 ].…”