Convenient Access to Functionalized Vinylcyclopentenols from Alkynyloxiranes
摘要:
beta,gamma-Alkynyl aldehydes, generated in situ by treatment of alkynyloxiranes with a catalytic amount of Sc(OTf)(3) or BF3 center dot OEt2, are effectively trapped by a variety of allyl nucleophiles to afford homopropargylic homoallylic alcohols in good yield and selectivity. Such products are used as substrates for the synthesis of functionalized vinylcyclopentenols via enyne metathesis.
Preparation of Chiral Allenes through Pd-Catalyzed Intermolecular Hydroamination of Conjugated Enynes: Enantioselective Synthesis Enabled by Catalyst Design
作者:Nathan J. Adamson、Haleh Jeddi、Steven J. Malcolmson
DOI:10.1021/jacs.9b02637
日期:2019.5.29
surrogate to afford primary amines in a two-step/one-pot process. Examination of chiral catalysts revealed a high degree of reversibility in the C-N bond formation that negatively impacted enantioselectivity. Consequently, an electron-poor ferrocenyl-PHOX ligand was developed to enable efficient and enantioselective enyne hydroamination.
Cu/Pd-catalyzed enantioselectivesynthesis of multisubstituted allenes is established. By employing chiral sulfoxide phosphine (SOP)/Cu and PdCl2 (dppf) complexes as catalysts, the 1,4-arylboration of 1,3-enynes provides an efficient approach to trisubstituted chiralallenes with up to 92 % yield and 97:3 er. Furthermore, by using 2-substituted 1,3-enynes as substrates, the tetrasubstitutedchiralallenes were
建立了铜/钯催化的多取代烯的对映选择性合成。通过使用手性亚砜膦(SOP)/ Cu和PdCl2(dppf)配合物作为催化剂,1,3-烯炔的1,4-芳基硼化提供了一种高效的三取代手性异戊烯的方法,收率高达92%和97:3 er 。此外,通过使用2-取代的1,3-烯炔作为底物,使用该策略成功地产生了四取代的手性烯丙基。最后,理论计算表明,烯丙基铜物种的金属转移是该转变的限速步骤。
Enantio‐ and Diastereoselective Synthesis of Homopropargyl Amines by Copper‐Catalyzed Coupling of Imines, 1,3‐Enynes, and Diborons
作者:Srimanta Manna、Quentin Dherbassy、Gregory J. P. Perry、David J. Procter
DOI:10.1002/anie.201915191
日期:2020.3.16
An efficient, enantio- and diastereoselective, copper-catalyzed coupling of imines, 1,3-enynes, and diborons is reported. The process shows broad substrate scope and delivers complex, chiral homopropargyl amines; useful building blocks on the way to biologically-relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single
Alkynylcyclopropanes have been used for the first time as coupling partners in transition-metal-catalyzed C–H functionalization. Specifically, a Cp*RhIII-catalyzed regioselective annulation of alkynylcyclopropanes with N-aryloxyamides via redox-neutral C–H/C–Cactivation has been developed, which affords highly functionalized 2,3-dihydrobenzofurans bearing an (E)-exocyclic carbon–carbon double bond
Catalytic, Enantioselective Synthesis of Allenyl Boronates
作者:De-Wei Gao、Yiyang Xiao、Mingyu Liu、Zhen Liu、Malkanthi K. Karunananda、Jason S. Chen、Keary M. Engle
DOI:10.1021/acscatal.8b00626
日期:2018.4.6
to achieve enantioselective 1,4-hydroboration of terminal and internal enynes to access allenyl boronates under CuH catalysis is described. The reaction typically proceeds in a highly stereoselective manner and tolerates an array of synthetically useful functional groups. The utility of the enantioenriched allenyl boronate products is demonstrated through several representative downstream derivatizations