通过在磷腈和腈官能团之间发生不寻常的氮杂-维蒂希反应并提供吡咯衍生的亚氨基磷腈,进行了α-EWG取代(吸电子基团,EWG)γ-叠氮基丁腈的转化。发现α-EWGs控制化学选择性,并取决于其性质,在氮杂-Wittig反应中充当CN基团活化剂(例如,酯,酰胺或腈)或竞争剂(例如,酮)。为了证明所得亚氨基磷腈作为N,N-双亲核试剂的合成效用,将其转化为吡咯稠合体系,即吡咯并[1,2- a ]咪唑和吡咯并[1,2- a ] [1,3]二氮杂s。执行。
Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
作者:Xianghua Yang、Thomas Fox、Heinz Berke
DOI:10.1039/c1ob06381b
日期:——
spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concertedtransitionstate. The very reactive intermediate
极化烯烃的无金属转移氢化(RR'C CEE':R,R'= H或有机基,E,E'= CN或 CO 2我)使用胺硼烷加合物 RR'NH–BH 3(R = R'= H,AB ; R = Me,R'= H,人与生物圈; R = t Bu,R'= H,tBAB; R = R′=我,DMAB通过原位NMR光谱研究作为氢供体的H 2O。氘 动力学同位素效应和所追踪的硼氢化中间体表明,双H转移过程在两个步骤中都发生了区域特异性反应 氢化物质子转移前的特征。对取代基效应和Hammett相关性的研究表明,^ h ñ转移与一致的过渡状态相一致。由AB生成的非常活泼的中间体[NH 2 BH 2 ]通过添加二甲醚被捕集环己烯 进入反应混合物形成 Cy 2 BNH 2。最终产品硼嗪假定(BHNH)3是通过[NH 2 BH 2 ]或其溶剂稳定的衍生物[NH 2 BH 2 ]-(溶剂)脱氢偶联形成的,而不是通过环三硼烷[NH
trans-Selective hydrocyanation of ynoates, ynones and ynoic acids catalyzed by nucleophilic phosphines
the presence of TMSCN and an alcohol additive are catalyzed by nucleophilicphosphines. The trisubstituted E-olefin products of anti-addition of hydrogen cyanide to the alkyne are produced with high regio- and stereoselectivity. The alcohol additive reacts with TMSCN to produce hydrogen cyanide in situ. Ynoic acids undergo the phosphine catalyzed hydrocyanation in the presence of TMSCN under aprotic
Abstract Knoevenagelcondensation of various aromatic and heteroaromatic aldehydes with active methylene compounds like methyl and ethyl cyanoacetate, malononitrile, and cyanoacetamide proceeds smoothly with stirring in water in the presence of 4 mol% of diammonium hydrogen phosphate. The reactions were carried out at room temperature in short periods with very simple workup procedure and good to high
t-butoxide catalyses the title reaction between aromatic aldehydes and malononitrile or alkyl cyanoacetates. At ambient temperatures, this procedure specifically gives high yields of E olefinic Knoevenagel products.
Asymmetric1,4-addition of arylboronicacids to (E)-methyl 2-cyano-3-arylpropenoates proceeded in the presence of a rhodium catalyst (3 mol %) coordinated with a chiral diene ligand, (R,R)-Ph-bod*, to give high yields of the corresponding methyl 3,3-diaryl-2-cyanopropanoates with high enantioselectivity (up to 99% ee). This catalytic asymmetric transformation was applied to the asymmetric synthesis
在具有手性二烯配体(R,R)-Ph- bod *,以高对映选择性(至多99%ee)得到高产率的相应的3,3-二芳基-2-氰基丙酸甲酯。该催化不对称转化应用于(R)-托特罗定的不对称合成。