Linear and macrocyclic ligands containing alternating pyridine and imidazolidin-2-one units 1
作者:Otto Meth-Cohn、Zegui Yan
DOI:10.1039/a707131k
日期:——
Linear oligomers of alternating 2,6-disubstituted pyridine (P) and N,N′-disubstituted imidazolidine-2-one (I) units have been made rapidly and in high yield with up to nine repeating units, terminating in either pyridine or imidazolidin-2-one units, or one of each. Synthetic methods include: (1) the sodium hydride-mediated condensation of N-(tert-butyl)imidazolidin-2-one with 2,6-difluoropyridine (F-P-F) or with higher analogues such as F-PIP-F, to give IPI, IPIPI and IPIPIPI. (The tert-butyl protection is readily and quantitatively removed with acid.) (2) The caesium fluoride catalysed interaction of N,N′-[dimethyl-(1,1,3-trimethylpropyl)]-protected IPI with But-IP-F sequentially leads firstly to IPIPIPI which by the same method reacts with F-P-F to give F-PIPIPIPIP-F. (3) F-P-F also reacts with 1,2-ethylenediamine (E) sequentially to give F-PEP-F, EPEPE and F-PEPEPEP-F while similar reactions starting from F-PIP-F give EPIPE and F-PEPIPEP-F in sequence. Alternative routes examined include: (1) the interaction of F-P-F with imidazole to give 2,6-bis(imidazol-1-yl)pyridine and salts therefrom followed by (unsuccessful) oxidation. (2) The reaction of 2,6-diaminopyridine with 2-chloroethyl isocyanate followed by cyclisation to give IPI. (3) The interaction of 2,6-diaminopyridine with oxalate esters (O) to give OPO or H2N-POP-NH2, the latter of which was reduced to H2N-PEP-NH2.Cyclisation of the linear assemblies was not successful. However macrocyclic systems were made by linking two IPI units with two ethoxyethyl or with two ethoxyethoxyethyl units. Also two F-PIP-F units were similarly reacted to give polyether-linked macrocycles. Mono- and bis-prop-2-ynylated IPI derivatives were made but could not be cyclised. Attempts to cyclise ethylenediamine and oxamide based systems were also unsuccessful. The linear and macrocyclic ligands showed calcium selectivity in a study of their metal complexing abilities.
交替的2,6-二取代吡啶(P)和N,N′-二取代咪唑烷-2-酮(I)单元的线性低聚物已被迅速制备并获得高产率,最多可达九个重复单元,以吡啶或咪唑烷-2-酮单元之一或两者之一结束。合成方法包括:(1)N-(叔丁基)咪唑烷-2-酮与2,6-二氟吡啶(F-P-F)或更高类似物如F-PIP-F的钠氢化物介导的缩合反应,得到IPI、IPIPI和IPIPIPI。(叔丁基保护基可轻松且定量地通过酸去除。)(2)N,N′-[二甲基-(1,1,3-三甲基丙基)]保护的IPI与But-IP-F的氟化铯催化相互作用首先导致IPIPIPI,通过相同方法与F-P-F反应得到F-PIPIPIPIP-F。(3)F-P-F还与1,2-乙二胺(E)连续反应得到F-PEP-F、EPEPE和F-PEPEPEP-F,而从F-PIP-F开始的类似反应依次得到EPIPE和F-PEPIPEP-F。考察的其他路线包括:(1)F-P-F与咪唑相互作用得到2,6-双(咪唑-1-基)吡啶及其盐,随后进行(不成功的)氧化。(2)2,6-二氨基吡啶与2-氯乙基异氰酸酯反应,然后环化得到IPI。(3)2,6-二氨基吡啶与草酸酯(O)相互作用得到OPO或H2N-POP-NH2,后者被还原为H2N-PEP-NH2。线性聚合物的环化未成功。然而,通过两个IPI单元与两个乙氧基乙基或两个乙氧基乙氧基乙基单元的连接制备了大环体系。同样,两个F-PIP-F单元反应得到聚醚连接的大环。制备了单和双-丙-2-炔基化的IPI衍生物,但无法环化。尝试环化乙二胺和草酰胺基系统也不成功。线性和大环配体在金属配位能力研究中显示出对钙的选择性。