Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
作者:Daniel Meyer、Philippe Renaud
DOI:10.1002/anie.201703340
日期:2017.8.28
A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides
Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
作者:Moshood O. Ganiu、Alexander H. Cleveland、Jarrod L. Paul、Rendy Kartika
DOI:10.1021/acs.orglett.9b01959
日期:2019.7.19
The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the
A stereoselectivehypervalent iodine-promoted oxidative rearrangement of 1,1-disubstituted alkenes has been developed. This practically simple protocol provides access to enantioenriched α-arylated ketones without the use of transition metals from readily accessible alkenes.
Allenoates in Enantioselective [2+2] Cycloadditions: From a Mechanistic Curiosity to a Stereospecific Transformation
作者:Johannes. M. Wahl、Michael L. Conner、M. Kevin Brown
DOI:10.1021/jacs.8b10008
日期:2018.11.21
selectivity, a detailed mechanistic investigation was conducted. Herein, two competing reaction pathways are proposed, which operate simultaneously and funnel the alkenes to the same axially chiral cyclobutanes. In agreement with the Woodward-Hoffmannrules, this mechanistic curiosity can be rationalized through a unique symmetry operation that was elucidated by deuteration experiments. In the case of 1,1-diarylalkenes
Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
作者:T. V. RajanBabu、Nobuyoshi Nomura、Jian Jin、Malay Nandi、Haengsoon Park、Xiufeng Sun
DOI:10.1021/jo035171b
日期:2003.10.1
counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1
通过对配体和抗衡离子作用的系统检查,发现了用于乙烯和各种功能化乙烯基芳烃的近定量和高度选择性共聚的新方案。在典型的反应中,在-56℃下,在[CH2Cl2]中,在[CH3Cl2]中分别存在0.0035当量的[(烯丙基)NiBr] 2,三苯膦和AgOTf,4-溴苯乙烯和乙烯进行共二聚,得到3-(4-溴苯基)-1 -丁烯的收率和选择性均> 98%。与[(烯丙基)PdX] 2的相应反应效率低下且选择性低,在鉴定出可行的系统之前可能需要进一步优化。产生可比的产率和选择性的另一有用方案涉及使用由2-二苯基膦基苯甲酸烯丙酯,Ni(COD)2和(C 6 F 5)3 B制备的单组分催化剂。识别手性半不稳定配体(例如,(R)-2-甲氧基-2'-二苯基膦基-1,1'-联萘基,MOP)与高度离解的抗衡阴离子(BARF或SbF6)之间的协同关系Ni催化的反应的发展提出了开发合成3-芳基丁烯的实用路线的前景。可以从这