Carbon Radical Attack on a Pyrimidine Nitrogen. An Unusual Entry into Polycyclic Aminopyrimidones
摘要:
Unprecedented examples of a synthetically useful radical ring closure onto a pyrimidine nitrogen leading to novel, highly functionalized bi- and tricyclic pyrimidone structures are reported. An unexpected hydrogen atom translocation prior to the cyclization step was observed in some cases.
S-Succinimidomethyl- and S-phthalimidomethyl xanthates are added efficiently to various alkenes resulting in an overall aminomethylation process. In contrast, under similar conditions, S-pyrrolidonyl xanthate gives rise mostly to oligomers. This unexpected difference in reactivity is attributed to the more important allylic character of the intermediate radical in the case of the imide derivative as compared to the lactam.
Xanthate-mediated intermolecular alkylation of pyrazines
作者:Qi Huang、Ling Qin、Samir Z. Zard
DOI:10.1016/j.tet.2018.08.040
日期:2018.10
An expedient approach for the intermolecular C-H functionalization of pyrazines and other heteroarenes by the radical chemistry of xanthates is reported. Incorporation of a multitude of functional alkyl groups onto these heteroarenes proceeds in good yield and good to excellent regioselectivity, leading to highly functionalized heteroaromatics.
Tri- and Tetrasubstituted Functionalized Vinyl Sulfides by Radical Allylation
作者:Laurent Debien、Marie-Gabrielle Braun、Béatrice Quiclet-Sire、Samir Z. Zard
DOI:10.1021/ol403103u
日期:2013.12.20
2-Fluoropyridinyl-6-oxy- precursors derived from phenyl vinyl sulfide react with radicals generated from xanthates via an addition–elimination process to furnish the corresponding vinyl sulfides in good yields. This convergent method is operationally simple and enables a straightforward synthesis of the difficult to access tetrasubstituted vinyl sulfides. Vinyl sulfides were used as more robust enol ether surrogates
Degenerative xanthate transfer to olefins under visible-light photocatalysis
作者:Atsushi Kaga、Xiangyang Wu、Joel Yi Jie Lim、Hirohito Hayashi、Yunpeng Lu、Edwin K L Yeow、Shunsuke Chiba
DOI:10.3762/bjoc.14.283
日期:——
The degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [IrdF(CF3)ppy}2(dtbbpy)](PF6) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and photophysical studies revealed that the process operates under a radical chain mechanism, which is initiated through triplet-sensitization of xanthates by the long-lived triplet state
Radical <i>ipso</i>-Substitution of a Carbon–Fluorine Bond Leading to Fluoro-7-azaindolines and Fluoro-7-azaindoles
作者:Zhibo Liu、Ling Qin、Samir Z. Zard
DOI:10.1021/ol500985f
日期:2014.5.16
Rare examples of a synthetically useful radical ipso-substitution of a carbon–fluorine bond are reported, leading to highly functionalized 5,6-difluoro-7-azaindolines. An unexpected hydrogen atom translocation and fragmentation with loss of molecular nitrogen and formation of a nitrile were observed in the case of an N-benzyl-tetrazole derivative.
Radical Instability in Aid of Efficiency: A Powerful Route to Highly Functional MIDA Boronates
作者:Béatrice Quiclet-Sire、Samir Z. Zard
DOI:10.1021/jacs.5b03893
日期:2015.6.3
The inability of the sp(3) boron in MIDA boronates to stabilize an adjacent radical makes possible the efficient addition of a wide array Of xanthates to vinyl MIDA boronate, leading to highly functionalized and diverse aliphatic organoboron structures. The lack of radical Stabilization also allows the exchange Of the Xanthate in the adducts with a bromine. In one case, the bromine was substituted to generate a cyclopropyl MIDA derivative.