Enantioselective Desymmetrization of Cyclobutanones Enabled by Synergistic Palladium/Enamine Catalysis

Abstract

The enantioselective intramolecular α-arylation of cyclobutanones has been established by combining palladium and enamine catalyst systems. Two different enantioselective control strategies have been developed for cyclobutanone substrates bearing O- or N-tethered aryl bromides. Further synthetic applications are also reported.

Enantioselective Cross‐Exchange between C−I and C−C σ Bonds

“…Then two sequential reductive eliminations of C(sp 2 )−C(sp 2 ) and C(sp 3 )−I bonds could form the indanones 2 bearing an alkyl iodide group. In addition, enantioselective desymmetrization of prochiral cyclobutanones has been developed by the groups of Murakami, Cramer, Dong, and Lu . We expect that one of the two C(sp 2 )−C(sp 3 ) bonds 1 could be selectively cleaved using a chiral ligand (step A to B ), thus providing chiral 2 bearing an all‐carbon quaternary stereocenter .…”

Photoinduced C—C Bond Cleavage and Oxidation of Cycloketoxime Esters

“…The substrate 1ba displayed Ep 0/−1 ＝-0.91 V vs SCE and afforded the product 2aa in a similar yield (entry 5). [24] Further transformations of the synthesized chiral cyclobutanones 11a-11b had also shown the versatility of our method. Although the reduction profile of oxime 1ea (Ep 0/−1 ＝-0.88 V vs SCE) was matched with the photocatalyst, we detected the desired product 2aa in 40% yield along with (E)-5-phenylpent-4-enenitrile as a byproduct (entry 8).…”

Enantioselektive Desymmetrisierung von Cyclobutanonen: Eine Schnellstraße zu molekularer Komplexität

“…Basierend auf den Arbeiten von Jia et al [16] und Britton et al [17] hat die Gruppe um Lu eine Arbeit zur Desymmetrisierung von Cyclobutanonen durch a-Arylierung verçffentlicht. [18] vilegiert Cyclobutanone füre ine Reihe von Ringerweiterungen.…”