Synthesis of All‐Carbon Quaternary Centers by Palladium‐Catalyzed Olefin Dicarbofunctionalization
作者:Maximilian Koy、Peter Bellotti、Felix Katzenburg、Constantin G. Daniliuc、Frank Glorius
DOI:10.1002/anie.201911012
日期:2020.2.3
The redox-neutral dicarbofunctionalization of tri- and tetrasubstituted olefins to form a variety of (hetero)cyclic compounds under photoinduced palladium catalysis is described. This cascade reaction process was used to couple styrenes or acryl amides with a broad range of highly decorated olefins tethered to aryl or alkyl bromides (>50 examples). This procedure enables one or two contiguous all-carbon
Treatment of various organic halides with phosphinic acid (hypophosphorous acid) in aqueous ethanol in the presence of a radical initiator and a base gave the corresponding reduced products in high yields. Addition of a base is indispensable for the reduction of halides by phosphinic acid. Allylic ether of o-iodophenol or 2-haloalkanal allylic acetal underwent radical cyclization under the same conditions
A highly modular radical cascade strategy based upon radical cyclisation/allylic substitution sequence between alkyl/aryl bromides, 1,3-dienes and nucleophiles ranging from sulfinates to amines, phenols and 1,3-dicarbonyls is described (>80 examples). Palladium phosphine complexes – which merge properties of photo- and cross coupling-catalysts – allow to forge three bonds with complete 1,4-selectivity
Development of Radical Reactions with Zirconocene Complexes as Electron Transfer Reagents
作者:Kazuya Fujita、Hideki Yorimitsu、Koichiro Oshima
DOI:10.1246/bcsj.77.1727
日期:2004.9
Moreover, the reduction could function by using a catalytic amount of Cp 2 ZrCl 2 . A zirconocene-olefin complex also induced reductive radical cyclization of 2-haloalkyl allyl ethers in THF. This complex served as a single electrontransferreagent to promote the radical cyclization. Furthermore, the cyclization reaction in DME afforded 3-tetrahydrofuranylmethylzirconium efficiently.
Triethylborane-induced radical reduction of organic halides with tri-2-furanylgermane provided the corrresponding reduced compounds in good yields. Radical cyclization of β-haloalkyl allyl ether or 6-halo-1-alkene afforded five-membered products under the same reaction conditions. These reactions proceeded with NaBH4 in the presence of a catalytic amount of germanium hydride.