Diverse functionalized quinoxalines were synthesized in good yields from arylamines and readily available β-keto oximes through condensation and metal-free N-arylation. The reaction was compatible with various functional groups, such as halides, cyano, and esters. A mechanism was proposed based on the experimental results. These quinoxalines were easily obtained on a gram scale and converted to various useful scaffolds. Compound LASSBio-1022 was prepared in 83% yield in two steps.
A wide variety of novel non‐hygroscopic N‐oxide tetraphenylborate salts were synthesized and evaluated as co‐oxidants in the Ley–Griffith (TPAP) oxidation of benzylic and allylic alcohols under non‐anhydrous conditions. The novel DABCOO·TPB (2:1) salt was herein unearthed as a viable competitor to the first‐generation NMO·TPB (2:1) salt, but more importantly gave increased performance under oxidative competition. X‐ray crystal structure analysis and NMR spectroscopy revealed that depending on the crystallization conditions 1:1, 2:1 or 3:2 N‐oxide–tetraphenylborate salts could be formed.
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