Syntheses, X-ray structures and conformational studies of tetraoxa[n.n]metacyclophanes
作者:Takuji Ogawa、Tomoaki Kishimoto、Keijiro Kobayashi、Noboru Ono
DOI:10.1039/a705995g
日期:——
New types of macrocyclic ligands with tetraoxa[n.n]metacyclophane molecular skeletons have been synthesized. The structures of 14,28-dibromo-1,8,15,22-tetraoxa[8.8]metacyclophane 2a, 16,32-dibromo-1,10,17,26-tetraoxa[10.10]metacyclophane 2b, 14,28-dibromo-2,7,16,21-tetraoxa[8.8]metacyclophane 3a, 16,32-dibromo-2,9,18,25-tetraoxa[10.10]metacyclophane 3c, 18,36-dibromo-2,11,20,29-tetraoxa[12.12]metacyclophane 3d, 20,40-dibromo-2,13,22,33-tetraoxa[14.14]metacyclophane 3e and 14,28-diiodo- 2,7,16,21-tetraoxa[8.8]metacyclophane 9a have been determined by single-crystal X-ray structure analyses. In compounds 2a and 2b, two bromide atoms face each other within the macrocyclic ring while in compounds 3c, 3d and 3e the bromine atoms face in opposite directions, outwards from the macrocyclic ring. In the smaller ring compounds 3a and 9a the structure was intermediate between these two types.Substitution of the bromine atoms via lithiation has been achieved smoothly with iodine and methyl iodide as the electrophiles to afford disubstituted compounds in good yields, while with trimethylsilyl chloride as the electrophile the mono-substituted compound has been obtained.
新型的具有四氧杂[n.n]甲桥并苯分子骨架的大环配体已被合成。通过单晶X射线结构分析确定了14,28-二溴-1,8,15,22-四氧杂[8.8]甲桥并苯2a、16,32-二溴-1,10,17,26-四氧杂[10.10]甲桥并苯2b、14,28-二溴-2,7,16,21-四氧杂[8.8]甲桥并苯3a、16,32-二溴-2,9,18,25-四氧杂[10.10]甲桥并苯3c、18,36-二溴-2,11,20,29-四氧杂[12.12]甲桥并苯3d、20,40-二溴-2,13,22,33-四氧杂[14.14]甲桥并苯3e和14,28-二碘-2,7,16,21-四氧杂[8.8]甲桥并苯9a的结构。在化合物2a和2b中,两个溴原子相对地位于大环内部,而在化合物3c、3d和3e中,溴原子则相对地向大环外部。在较小环的化合物3a和9a中,结构介于这两种类型之间。通过锂化反应,利用碘和甲基碘作为亲电试剂,顺利地实现了溴原子的取代,得到了产率良好的二取代化合物,而使用三甲基氯硅烷作为亲电试剂时,则得到了单取代的化合物。