受铑催化羧酸经济向丙二烯中添加羧酸的机理研究的启发,已开发出铑催化的不同亲核试剂与消旋烯丙基碳酸酯的动态动力学不对称烯丙基化反应。在中性条件下可以获得很高的区域选择性和对映选择性,此外,化学选择性可以通过不同的二膦配体来控制。(R,R)-QuinoxP *导致酚的选择性O-烯丙基化,而当嵌入(S,S)-DIOP作为配体时,2-萘酚首次以高对映选择性被邻-C-烯丙基化。为此,羟基吡啶可以通过Rh I /(S)-DTBM-Segphos的中间体与先前报道的对丙二烯的原子经济加成反应相同。
Selective Cross-Coupling of Organic Halides with Allylic Acetates
摘要:
A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates.
Chemo- and regioselective reductive transposition of allylic alcohol derivatives <i>via</i> iridium or rhodium catalysis
作者:Rylan J. Lundgren、Bryce N. Thomas
DOI:10.1039/c5cc07993d
日期:——
The selective, catalytic deoxygenation of alcohols remains a persistent challenge in organic synthesis. Pd-catalyzed formate reduction and diazene-mediated reductivetransposition are both valuable strategies for the selective deoxygenation of allylic...
Regioselective and enantiospecific rhodium-catalyzed allylic amination with thymine: synthesis of a new conformationally rigid nucleoside
作者:P. Andrew Evans、Kwong Wah Lai、Hai-Ren Zhang、John C. Huffman
DOI:10.1039/b513083b
日期:——
The regioselective and enantiospecific rhodium-catalyzed allylic amination of secondary allylic carbonates with N3-benzoyl thymine in conjunction with a stereoselective free radical cyclization provides a convenient method for the construction of a new conformationally rigid nucleoside.
Co‐catalyzedallylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co‐catalyzedallylicalkylation using an in situ catalyst activation by organophotoredox catalysis. This noble‐metal‐free catalytic system exhibits unprecedentedly high reactivities
Rhodium‐Catalyzed Chemodivergent Regio‐ and Enantioselective Allylic Alkylation of Indoles
作者:Minghe Sun、Min Liu、Changkun Li
DOI:10.1002/chem.202004613
日期:2021.2.15
C3/N1 chemoselectivity in indole alkylation with the same electrophiles is still challenging. An Rh/bisoxazolinephosphane‐catalyzed chemodivergent regio‐ and enantioselectiveallylicalkylation of indoles was developed. Chiral C3‐ and N1‐allylindoles can be selectively obtained with high branched/linear ratio and up to 99 % ee by changing the counteranion of Rh, the allylic carbonate, the reaction temperature
Rh(I)/Bisoxazolinephosphine-Catalyzed Regio- and Enantioselective Allylic Substitutions
作者:Wen-Bin Xu、Samir Ghorai、Wenyu Huang、Changkun Li
DOI:10.1021/acscatal.0c00712
日期:2020.4.17
Rhodium(I)/bisoxazolinephosphine combination has been developed as a general catalyst to achieve the dynamic kinetic asymmetric allylation of a variety of nitrogen, carbon, oxygen, and sulfur pronucleophiles from branched racemic allylic carbonates. Exclusive branch-selectivity and up to 99% enantiomeric excess could be obtained under neutral conditions. Linear allylic substrates (both Z and E) could