In Situ Formation of Allyl Ketones via Hiyama−Nozaki Reactions Followed by a Chromium-Mediated Oppenauer Oxidation
作者:Henri S. Schrekker、Martin W. G. de Bolster、Romano V. A. Orru、Ludger A. Wessjohann
DOI:10.1021/jo001750u
日期:2002.4.1
dependent on the substitution pattern of the reaction partners and the reaction conditions. An appropriate choice of these can lead to preferential formation of ketones instead of the alcohols. In addition to its synthetic usefulness, the oxidation-reduction equilibrium is of the utmost importance for the design of enantioselective Hiyama-Nozaki reactions because it is also a potential racemization pathway
An efficient N-centred radical 5-exo cyclization/addition/aromatization cascade by cooperative visible light photoredox and cobalt catalysis is described, giving dihydropyrazole-fused benzosultams in satisfactory yields.
Hydrazone Radical Promoted Vicinal Difunctionalization of Alkenes and Trifunctionalization of Allyls: Synthesis of Pyrazolines and Tetrahydropyridazines
作者:Xiao-Yong Duan、Xiu-Long Yang、Ran Fang、Xie-Xue Peng、Wei Yu、Bing Han
DOI:10.1021/jo4016908
日期:2013.11.1
achieved by using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) or DIAD (diisopropyl azodicarboxylate) as the hydrazone radical initiator as well as the carbon radical scavenger. Consequently, alkenes were difunctionalized to afford pyrazolines and tetrahydropyridazines via C–N forming 5-exo-trig and 6-exo-trig cyclizations, respectively, and allyls were trifunctionalized to afford pyrazolines via C–N forming
The trifluoromethylthiolation and trifluoromethanesulfonylation of β,γ-unsaturated hydrazones was accomplished with silver(I) trifluoromethanethiolate (AgSCF3) as a CF3S source and sodium trifluoromethylsulfinate (CF3SO2Na) as a CF3SO2 source, respectively. These general methods for the preparation of dihydropyrazoles containing CF3S or CF3SO2 groups were characterized by mild reaction conditions and
β,γ-不饱和的三氟甲硫基化和三氟甲磺酰化分别用三氟甲硫醇银(AgSCF 3)作为CF 3 S源和三氟甲亚磺酸钠(CF 3 SO 2 Na)作为CF 3 SO 2源来完成。这些制备含有CF 3 S或CF 3 SO 2基团的二氢吡唑的通用方法的特征在于温和的反应条件和良好的官能团耐受性。