α-Alkylation of tertiary amines by C(sp3)–C(sp3) cross-coupling under redox neutral photocatalysis
摘要:
Direct cc-alkylation of N-phenyl-tetrahydroisoquinoline with alkyl selenides of desired alkyl chain length and functionality is reported by photoredox catalysis. Construction of hexahydro pyrrolo- and pyrido-isoquinoline scaffolds along with indolines and tetrahydroquinolines is also described by intramolecular C(sp(3))-C(sp(3)) cross-couplings. (C) 2016 Elsevier Ltd. All rights reserved.
On the reactivity of indium(III) benzenechalcogenolates (chalcogen = sulfur and selenium) towards organyl halides for the synthesis of organyl phenyl chalcogenides
作者:Clovis Peppe、Liérson Borges de Castro
DOI:10.1139/v09-043
日期:2009.5
was examined. A practical one-pot method to prepare organyl phenyl chalcogenides from indium metal and diphenyl dichalcogenide was found. The coupling is fairly broad in scope and generally works better for organyl halides capable to produce stablecarbocations.
A convenient procedure for phenylselenenylation of alkylhalides, alkenyl sulfonates, and epoxides with phenyl selenide anion was accomplished by electroreduction of diphenyl diselenide in a protic solvent.
Radical intermediates in the Zn-promoted Barbier-type alkylation of diphenyl diselenide in aqueous medium
作者:José Ayron Lira dos Anjos、Lothar Wilhelm Bieber
DOI:10.1016/j.tetlet.2012.09.063
日期:2012.11
The zinc promoted Barbier-type reaction of alkylhalides and diphenyl diselenide in aqueous medium leads to high yields of mixed selenides even in acidic medium. Especially the efficient formation of t-butylphenylselenide cannot be explained by nucleophilicsubstitution and raises the question of an alternative reaction mechanism. Three suitable halide precursors of ‘radical clocks’ of increasing rate
method of unsymmetrical selenides has been developed. When diphenyldiselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl phenyl selenides were formed in moderate to good yields. For the reaction of primary alkyl chlorides and secondary alkyl iodides, the yields of the selenides were low; however,
Evidences of adduct formation between the dirhodium complex Rh2[(R)-MTPA4]
(Rh–Rh; MTPA-H = Mosher acid) and various monovalent ligands L were obtained in solution by using NMR spectroscopy. Strongly binding ligands, e.g. selenoethers or nitriles, prefer L
→
Rh–Rh
←
L adducts whereas weaker ligands, e.g. olefins with low steric hindrance, tend to form oligomers with bridging L molecules: ⋯Rh–Rh⋯L⋯Rh–Rh⋯. Larger steric congestion forces olefins to avoid bridge situations or even prohibits adduct formation at all.
利用核磁共振光谱法获得了二铑配合物 Rh2[(R)-MTPA4](Rh-Rh;MTPA-H = 莫舍酸)与各种单价配体 L 在溶液中形成加合物的证据。结合力强的配体(如硒化物或腈类)倾向于 L → Rh-Rh ← L 加合物,而结合力弱的配体(如立体阻碍小的烯烃)则倾向于与桥接的 L 分子形成低聚物:⋯Rh-Rh⋯L⋯Rh-Rh⋯。较大的立体拥塞会迫使烯烃避免架桥,甚至完全禁止加成物的形成。