Nitrogen Acyclic Gold(I) Carbenes: Excellent and Easily Accessible Catalysts in Reactions of 1,6-Enynes
摘要:
Complexes [AuCl{C(NHR)(NHR')}] and [AuCl{C(NHR)(NEt2)}] (R =Bu-t, p-Tol, Xylyl, p-C6H4-COOH, p-C6H4COOEt, R' = Me, Bu-n, Pr-i, (n)heptyl, p-Tol) have been prepared by reaction of the corresponding isocyanogold complexes [AuCl(CNR)] with either primary amines or diethylamine. All the prepared carbenes are reactive and highly selective catalysts for skeletal rearrangement, methoxycyclization of 1,6-enynes, and other mechanistically related gold-catalyzed transformations. Overall, these easily accessible nitrogen acyclic carbene (NAC) gold complexes were not second to NHC complexes and were advantageous to obtain different products.
Radical Borylation/Cyclization Cascade of 1,6-Enynes for the Synthesis of Boron-Handled Hetero- and Carbocycles
作者:Shi-Chao Ren、Feng-Lian Zhang、Jing Qi、Yun-Shuai Huang、Ai-Qing Xu、Hong-Yi Yan、Yi-Feng Wang
DOI:10.1021/jacs.7b01889
日期:2017.5.3
construct boron-handled cyclic molecules was developed based on a radical borylation/cyclization cascade of 1,6-enynes. The process was initiated by the chemo- and regio-controlled addition of an N-heterocyclic carbene-boryl radical to an alkene or alkyne, followed by ring closure to afford boron-substituted cyclic skeletons. Further molecular transformations of the cyclic products to synthetically
A variety of linear dienynes can deliver complex tetracyclicframeworks in the presence of an IrIII complex and visible light. Product formation involves the generation of four new C−C bonds and six contiguous stereocenters, which decorate two [3.1.0] bicyclic units tethered through their bridging quaternary carbon atoms. The internal alkyne acts as a formal dicarbenoid for the generation of two cyclopropanes
A sequential Rh(i)-catalyzed vinylation/[2 + 1]carbocyclization between enynes and diazo compounds has been developed. This transformation features a wide range of enynes and acceptor/acceptor diazo compounds, providing easy access to versatile vinyl-substituted azabicyclo[3.1.0]hexanes having a broad tolerance to functional groups.
A cascade of styrylynols promoted by MnO2 allows the synthesis of fused tricycles with a naphthalene core. The reaction occurs under ambient conditions, offering a practical synthetic tool because of the inexpensive and abundant manganese species. The method affords products through the sequential oxidation of a propargyl alcohol, stepwise Diels–Alder cyclization, and finally rearomatization. According
Described herein is a visible-light mediated intermolecular radicalcyclization approach to access heterocycles. Heteroatom radicals, such as silicon and phosphorus atom radicals, were generated via direct hydrogen atom abstraction by the photoexcited catalyst species with hydro-silanes and phosphineoxides. The radical addition/cyclization/HAT (hydrogen atom transfer) reaction sequences of 1,6-enynes