Development of methods for the sp2 C-H transformations of allenes has received much attention, and it presents a powerful tool for the synthesis of complicated allene-containing bioactive molecules. With a copper-catalyzed radical relay, the sp2 allenic C-H arylation and alkynylation were established herein, using various aryl boronic acids and trimethoxysilyl-substituted alkynes as carbon nucleophiles, and using electrophilic N-F reagents as nitrogen-centered radical precursors. These methods featured excellent site-selectivity to deliver fully substituted allenes efficiently. Moreover, with silyl-substituted allenes as substrates, a subsequential dual sp2 C-H functionalization process was established as well, which allowed for the divergent synthesis of multi-functionalized allenes, significantly expanding their chemical spaces. This result is published in JACS. Congratulations Zhongming Cheng.
We establish a remote hydrosulfonamidation (HSA) of alkenes using palladium catalysis, where N-fluoro-N-(fluoro-sulfonyl)-carbamate with a sulfur(VI) fluoride moiety is demonstrated as a good amidation reagent. The anti-Markovnikov HSA reaction of terminal alkenes and the remote HSA of internal alkenes are achieved to efficiently yield primary N-alkyl-N-(fluorosulfonyl)-carbamates. In addition, this protocol enables the high-value utilization of alkane by combining the dehydrogenation process. The generated N-alkyl products exhibit a unique reactivity of sulfur(VI) fluorides, which can be directly transferred to N-alkyl sulfamides or amines via the sulfur(VI) fluoride exchange reaction, thereby streamlining their synthesis. Moreover, a (pyridyl) benzazole-type ligand proved to be vital for the excellent chemo- and regioselectivities. This result is published in JACS. Congratulations Chanqi and Zhenye.
A palladium-catalyzed asymmetric 1,n-remote aminoacetoxylation of cis-alkenes has been developed using PhI(OAc)2 as an oxidant, providing the acetoxylated lactams with excellent enantioselectivities under mild reaction conditions. The sterically hindered pyridine-oxazoline (Pyox) L3 with a tert-butyl group in oxazoline ring and propyl group in C6 position of pyridinyl is vital for the reaction, where the former is good for asymmetric aminopalladation step and the latter for the chain walking process. The enantioenriched lactam products were proven to be good building blocks for the synthesis of azabicycles.This result is published in Angew. Chem. Congratulations Xintuo.