Chemical modification of plant alkaloids. I. Aminomethylation of barbituric acid derivatives by cytisine
摘要:
Reaction of cytisine with 1-mono- and 1,3-disubstituted 5-arylmethylbarbituric acids in the presence of formaldehyde results in aminomethylation of C-5 to form the corresponding 5-cytisylmethylbarbituric acids. The structures of the products are found using PMR spectroscopy mid mass spectrometry. 1-Phenyl-5-(2,4-dimethoxybenzyl)-5-cytisylmethylbarbituric acid is obtained as a mixture of two steroisomers in an approximately 2:1 ratio.
diastereoselective synthesis of perfluoroalkylated cis-spiropyrido[2,1-a]isoquinoline-1,5’-pyrimidine derivatives in good to excellent yields under mild conditions. The reaction mechanism was proposed to illustrate the formation of the diastereoisomers and proton-promoted transformation of trans-spiropyrido[2,1-a]isoquinoline-1,5’-pyrimidines to the more thermodynamically stable cis-isomers. The DFT calculation demonstrated
衍生自异喹啉和全氟烷基-2-炔酸甲酯的1,4-偶极易于与亚芳基取代的N,N-二甲基巴比妥酸反应,导致全氟烷基化的顺式-吡咯并[2,1- a ]异喹啉-1的第一个非对映选择性合成, 5'-嘧啶衍生物在温和条件下的产率高至优异。提出了反应机理以说明非对映异构体的形成和反式-吡咯并[ 2,1- a ]异喹啉-1,5'-嘧啶质子促进的转化为热力学更稳定的顺式异构体。DFT计算证明了反应的非对映选择性。
Synthesis of spirobarbiturate-pyrrolidinones <i>via</i> a domino aza-Michael/S<sub>N</sub>2 cyclization of barbiturate-derived alkenes with <i>N</i>-alkoxy α-haloamides
A highly efficient domino aza-MIRC (Michael Induced RingClosure) reaction between barbiturate-derived alkenes and N-alkoxy α-haloamides has been achieved in moderate to excellent yields. This reaction proceeds smoothly under mild conditions via a domino aza-Michael addition/intramolecular SN2 sequence, providing a practical tool in the synthesis of bioactive molecules spirobarbiturate-3-pyrrolidinones
The phosphine-catalyzed [3 + 2] annulation reaction of ynones and barbiturate-derived alkenes has been developed with the assistance of a weak acid, giving functionalized spirobarbiturate-cyclopentanones in moderate to excellent yields with excellent E/Z stereoselectivity. An unprecedented [4 + 2] annulation of ynones with barbiturate-derived alkenes was also achieved in the presence of a phosphine
A domino knoevenagel-phospha-michael reaction: One-pot synthesis of novel organophosphonates in the presence of multi-walled carbon nanotube‒CO‒NH(CH<sub>2</sub>)<sub>2</sub>NH-SO<sub>3</sub>H as catalyst
作者:Fatemeh Homayoun、Soheila Ghassamipour
DOI:10.1080/10426507.2018.1452230
日期:2018.7.3
one-pot method for the synthesis of various substituted 1,3-dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl phosphonate derivatives via phosphorus-carbon bondformation through domino Knoevenagel–phospha–Michael reaction. Multi-walled carbon nanotube‒CO‒NH(CH2)2NH-SO3H was used as an acidic heterogeneous catalyst. The catalyst could be used four times without losing its catalytic activity. The structures
Organocatalytic [3+2] Cycloadditions of Barbiturate-Based Olefins with 3-Isothiocyanato Oxindoles: Highly Diastereoselective and Enantioselective Synthesis of Dispirobarbiturates
Catalyzed by a Cinchona‐based thiourea, the [3+2] cycloadditions of barbiturate‐based olefins with 3‐isothiocyanatooxindoles proceeded readily, and furnished dispirobarbiturates in excellent chemical yields with excellent diastereo‐ and enantioselectivities. The absolute configuration of dispirobarbiturates was firmly confirmed by an X‐ray single crystal structure analysis. A reaction mechanism was