Asymmetric cyanation of nitroalkenes catalyzed by a salen–titanium catalyst
作者:Li Lin、Wen Yin、Xu Fu、Jinlong Zhang、Xiaojuan Ma、Rui Wang
DOI:10.1039/c1ob05899a
日期:——
The salenâTi complex catalyzed cyanation of nitroolefins was accomplished via the silyl nitronate intermediate for the synthesis of chiral β-nitronitriles with e.r. up to 92â:â8 and high yields (up to 90%). The catalyst also kept a high turnover frequency at room temperature. The yield and enantioselectivity of the protocol were slightly affected even in a 10 mmol scale.
Organocatalytic Asymmetric Cyanosilylation of Nitroalkenes
作者:Pablo Bernal、Rosario Fernández、José M. Lassaletta
DOI:10.1002/chem.201001107
日期:——
New catalyst, new reaction: The unprecedented cyanosilylation of nitroalkenes can be efficiently catalyzed by a bifunctional quinine derivative with tetraalkylammonium cyanide and thiourea moieties. The activation of the nitroalkene by hydrogen bonding to the thiourea, together with the presence of an “active” cyanide, provides a new mode of activation that leads to products in high yields and good
Synthesis of enantioenriched azo compounds: organocatalytic Michael addition of formaldehyde N-tert-butyl hydrazone to nitroalkenes
作者:David Monge、Silvia Daza、Pablo Bernal、Rosario Fernández、José M. Lassaletta
DOI:10.1039/c2ob26963e
日期:——
moderate enantioselectivities, up to 84 : 16 er; additional transformation of diazenes into their tautomeric hydrazones proved to be operationally simple and high-yielding, affording bifunctional compounds which represent useful intermediates for the synthesis of enantioenriched β-nitro-nitriles and derivatives thereof.
Asymmetric Hydrocyanation of Nitroolefins Catalyzed by an Aluminum(III) Salen Complex
作者:Ajay Jakhar、Arghya Sadhukhan、Noor-ul H. Khan、S. Saravanan、Rukhsana I. Kureshy、Sayed H. R. Abdi、Hari C. Bajaj
DOI:10.1002/cctc.201402373
日期:2014.9
Chiral AlIII salen complexes were synthesized and used as catalysts for the asymmetric hydrocyanation of nitroolefins using 4‐phenylpyridine N‐oxide as an additive and trimethylsilyl cyanide (TMSCN) as a source of cyanide. An excellent yield of β‐nitronitrile (87 %) and enantioselectivity (90 %) were achieved if (2‐nitrovinyl)cyclohexane was used as a substrate at −15 °C in 16 h. To understand the
合成了手性Al III salen配合物,并使用4-苯基吡啶N-氧化物作为添加剂和三甲基甲硅烷基氰化物(TMSCN)作为氰化物来源,将其用作硝基烯烃不对称氢氰化的催化剂。如果将(2-硝基乙烯基)环己烷用作底物,在-15°C下16小时,可获得良好的β-腈(87%)和对映选择性(90%)。为了了解Al III salen络合物与添加剂的相互作用,NMR和IR光谱研究表明4-苯基吡啶N-氧化物既充当轴向配体,又有助于激活氰化物源TMSCN,从而提高了反应活性。基于光谱学研究提出了催化循环。
Asymmetric Addition of Cyanide to β‐Nitroalkenes Catalysed by Chiral Salen Complexes of Titanium(IV) and Vanadium(V)
作者:Michael North、James M. Watson
DOI:10.1002/cctc.201300215
日期:2013.8
Structurally well-defined bimetallic titanium(IV) (salen) and monometallic vanadium(V) (salen) complexes have been used as catalysts for the asymmetricaddition of trimethylsilyl cyanide to beta-nitroalkenes to produce chiral nitronitriles with ee values in the range of 79-89 % and conversions up to 100 % at 0 degrees C. The reaction conditions (solvent, temperature, time and vanadium complex counter-ion)