2-Dihydromethylpiperazinediium-M<sup>II</sup>(M<sup>II</sup>= Cu<sup>II</sup>, Fe<sup>II</sup>, Co<sup>II</sup>, Zn<sup>II</sup>) double sulfates and their catalytic activity in diastereoselective nitroaldol (Henry) reaction
作者:Houcine Naïli、Fadhel Hajlaoui、Tahar Mhiri、Tatiana C. O. Mac Leod、Maximilian N. Kopylovich、Kamran T. Mahmudov、Armando J. L. Pombeiro
DOI:10.1039/c2dt31300f
日期:——
A series of double dihydromethylpiperazinediium metallic sulfates 1–7 [H2mpz]MII(SO4)2·nH2O (mpz = 2-methylpiperazine, C5H12N2) are prepared by slow evaporation using a racemic (R/S)-mpz (for 1, 2) or enantiopure R-mpz (for 3), S-mpz (for 4–7) and sulfates of CuII (for 5), FeII (for 1, 4), CoII (for 7) and ZnII (for 2, 3, 6), and characterized by infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. The [MII(H2O)6]2+, [(R/S)-H2mpz]2+, [(R)-H2mpz]2+ or [(S)-H2mpz]2+ cations and 2SO42− anions are linked together via two types of hydrogen bonds, Ow–Hw⋯O and N–H⋯O, leading to supramolecular arrangements. The use of the racemic 2-mpz provides alternatives in crystallization: a centrosymmetric structure where the enantiomers are related by an appropriate crystallographic symmetry operation or one where the enantiomers occupy the same crystallographic position, generating disorder. Compounds 1–7 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The diastereoselectivity can be regulated from exclusive threo to exclusive erythro isomer preparation with typical yields of 50–99%, depending on the catalyst and the substrate used.
一系列双二氢甲基哌嗪二铵金属硫酸盐1–7 [H2mpz]MII(SO4)2·nH2O(mpz = 2-甲基哌嗪,C5H12N2)通过缓慢蒸发法制备,使用了外消旋(R/S)-mpz(用于1、2)或对映体纯的R-mpz(用于3)、S-mpz(用于4–7)和洛铁(用于1、4)、铜(用于5)、钴(用于7)和锌(用于2、3、6)的硫酸盐,并通过红外光谱、元素分析和单晶X射线衍射进行表征。 [MII(H2O)6]2+、[(R/S)-H2mpz]2+、[(R)-H2mpz]2+或[(S)-H2mpz]2+阳离子与2SO42−阴离子通过两种类型的氢键(Ow–Hw⋯O和N–H⋯O)相互连接,形成超分子结构。使用外消旋的2-mpz提供了结晶方面的选择:一个中心对称结构,其中对映体通过适当的晶体对称操作相关联,或一个对映体占据相同的晶体位置,产生无序。化合物1–7作为氮丙醇(亨利)反应的二叠体选择性催化剂。二叠体选择性可从独占的threo异构体调节到独占的erythro异构体制备,典型产率为50–99%,取决于所使用的催化剂和底物。