Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters
作者:Zubao Gan、Deyun Cui、Hongyun Zhang、Ying Feng、Liying Huang、Yingying Gui、Lu Gao、Zhenlei Song
DOI:10.3390/molecules27154730
日期:——
(Ph3C)[BPh(F)4]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.
beta-Phenylselanyl alpha-oxoesters 2 were prepared by N-phenylselanyl morpholine treatment of alpha-oxoesters 1, oxidized into beta-unsaturated alpha-oxoesters 5 and subjected to the Wittig-Horner olefination. The diethyl (1-phenylselanylalkyl)maleates 6 have led, after [2,3]sigmatropic rearrangement of the corresponding selenoxides, to the diethyl 3-alkylidene-2-hydroxysuccinates 7. The 2-(t-butoxycarbonylamino)-3-alkylidenesuccinates 8 were prepared in a similar way. The decomposition of halo-adducts derived from compounds 6 has allowed the synthesis of the diethyl 3-alkylidene-2-halosuccinates 9 and 10. (C) 1997 Elsevier Science Ltd.