通过膦酸三乙酯和(杂)芳族羰基化合物之间的霍纳-沃兹沃斯-埃蒙斯反应,使用质子、无毒且可生物降解的低共熔溶剂开发了一种新的可规模合成( E )-α,β-不饱和酯,包括吸电子基团和给电子基团。在LiOH、K 2 CO 3或DBU作为碱的存在下,在室温和空气下实现二取代或三取代的肉桂酸乙酯衍生物的立体选择性制备。通过 ( E )-3-(4-溴苯基)丙烯酸乙酯的合成证明,相同的低共熔混合物(氯化胆碱/尿素)被证明可在连续三次运行中重复使用。可以进行克级反应(10 mmol)而不会形成副产物,从而确保高原子经济性和EcoScale评分为71。
Highly E-selective solvent-free Horner–Wadsworth–Emmons reaction catalyzed by DBU
作者:Kaori Ando、Kyohei Yamada
DOI:10.1039/c1gc15134g
日期:——
The solvent-free Horner–Wadsworth–Emmons reaction of triethylphosphonoacetate with a variety of aldehydes was catalyzed by DBU in the presence of K2CO3 to give E-α,β-unsaturated esters highly selectively (99:1 for most of the reactions). The reaction with ketones gave trisubstituted olefins with good to high E-selectivity by DBU-Cs2CO3.
这 溶剂无Horner–Wadsworth–Emmons的反应 膦酸三乙酯 与各种 醛类DBU在K 2 CO 3的存在下催化得到E -α,β-不饱和酯类高度选择性(大多数反应为99 :1)。与之反应酮类 给出三取代 烯烃DBU-Cs 2 CO 3具有良好的电子选择性,甚至具有很高的电子选择性。
Catalytic hydrogenation of α,β-unsaturated carboxylic acid derivatives using copper(<scp>i</scp>)/N-heterocyclic carbene complexes
作者:Birte M. Zimmermann、Sarah C. K. Kobosil、Johannes F. Teichert
DOI:10.1039/c8cc09853k
日期:——
air-stable copper(I)/N-heterocyclic carbene complex enables the catalytic hydrogenation of enoates and enamides, hitherto unreactive substrates employing homogeneous copper catalysis and H2 as a terminal reducing agent. This atom economic transformation replaces commonly employed hydrosilanes and can also be carried out in an asymmetric fashion.
Highly Enantioselective Iridium-Catalyzed Hydrogenation of α,β-Unsaturated Esters
作者:Jia-Qi Li、Xu Quan、Pher G. Andersson
DOI:10.1002/chem.201200907
日期:2012.8.20
α,β‐Unsaturated esters have been employed as substrates in iridium‐catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic‐ and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural
The contra-thermodynamic isomerization of α- and β-substituted cinnamate derivatives catalyzed by the Cu(OAc)2/rac-BINAP complex under blue light irradiation is reported. The use of an oxazolidinone template, which favored the complexation of the copper catalyst to the substrate, allowed the E → Z isomerization of the catalytically formed chromophore under simple and robust reaction conditions in good
N-Heterocyclic Carbene-Catalyzed Cyclization of Unsaturated Acyl Chlorides and Ketones
作者:Li-Tao Shen、Pan-Lin Shao、Song Ye
DOI:10.1002/adsc.201100178
日期:2011.8
synthesis of optically active trifluoromethyl dihydropyranones and spirocyclic oxindole-dihydropyranones has been realized by the chiral N-heterocyclic carbenes-catalyzed cyclization of α,β-unsaturated β-methylacyl chlorides with activated trifluoromethyl ketones or isatin derivatives.