Enantioselective Addition of Pyrazoles to Dienes**
作者:Alexander Y. Jiu、Hannah S. Slocumb、Charles S. Yeung、Xiao‐Hui Yang、Vy M. Dong
DOI:10.1002/anie.202105679
日期:2021.9
We report the first enantioselectiveaddition of pyrazoles to 1,3-dienes. Secondary and tertiary allylic pyrazoles can be generated with excellent regioselectivity. Mechanistic studies support a pathway distinct from previous hydroaminations: a Pd0-catalyzed ligand-to-ligand hydrogen transfer (LLHT). This hydroamination tolerates a range of functional groups and advances the field of diene hydrofunctionalization
5-di(tert-butyl)pyrazole (3d), 3,5-bis(trifluoromethyl)pyrazole (3e)). The synthesis approach thus provides access to uncharged B–N triptycenes bearing (i) functionalisable groups, (ii) electron-donating or -withdrawing substituents and (iii) pyrazole rings of varying steric demand. Treatment of p-R*C6H4BBr2 with the potassiumtris(pyrazol-1-yl)borates K[HBpz3] or K[p-R*C6H4Bpz3] yields cationic pyrazolyl-bridged
在Me 3 SiCl存在下,双硼酸酯Li 2 [ o -C 6 H 4(BH 3)2 ]与2当量适当的吡唑衍生物(Hpz R)之间的反应产生邻苯撑桥连的吡唑HB(μ- pz R)2(μ- o -C 6 H 4)BH(3a-3e ; Hpz R = 4-碘吡唑(3a),4-(三甲基甲硅烷基)吡唑(3b),3,5-二甲基吡唑(3c),3 ,5-二(叔)-丁基)吡唑(3d),3,5-双(三氟甲基)吡唑(3e))。因此,该合成方法可提供带有(i)可官能化基团,(ii)给电子或吸电子取代基和(iii)空间需求变化的吡唑环的不带电荷的B-N三联烯。用三(吡唑-1-基)硼酸钾K [HBpz 3 ]或K [ p- R * C 6 H 4 Bpz 3 ]处理对-R * C 6 H 4 BBr 2产生阳离子吡唑基桥连的吡唑并[ p -BrC 6 H 4 B(μ-pz)3 BH] Br([4a ] Br)和[ p
Platinum and Gold Catalysis: à la Carte Hydroamination of Terminal Activated Allenes with Azoles
作者:José Miguel Alonso、María Paz Muñoz
DOI:10.1021/acs.orglett.9b02949
日期:2019.9.20
methodology to achieve selective addition of azoles to the proximal or distal carbon of activated allenes depending on the catalyst used, unravelling a gold–platinum bimetallic catalysis approach for the 1,3-double addition of azoles to activated allenes to give 1,3-bisazole derivatives, an important scaffold in medicinal and organometallic chemistry.
The unique property of hexafluoroisopropanol (HFIP) enables the regioselective hydroamination of 1,3-dienes with nitrogen heterocycles in a Markovnikov manner in the presence of catalytic Brønsted acid. This transition-metal-free intermolecular hydroamination protocol is achieved under mild reaction conditions. The aggregation by HFIP and Brønsted acid helps to activate the terminal double bond regioselectively
New monomeric N-borylated pyrazole and imidazole derivatives have been synthesized and some of their characteristic features have been explored. The suggested structures are supported by spectroscopic data.