The Diels–Alder reactivity of nitrobenzofuroxans: mono- and di-adducts of isoprene and 2,3-dimethylbutadiene. New convenient precursors to naphtho- and phenanthreno-furoxanic and -furazanic structures
作者:Régis Goumont、Muriel Sebban、Patricia Sépulcri、Jérome Marrot、François Terrier
DOI:10.1016/s0040-4020(02)00236-3
日期:2002.4
The reactions of a series of differently substituted nitrobenzofuroxans with isoprene and 2,3-dimethylbutadiene have been investigated. A variety of mono- and di-adducts resulting from normal electron demand Diels–Alder condensations involving the activated C6C7 and/or C4C5 double bonds of the carbocyclic ring as the dienophile contributors have been identified and structurally characterized. The regioselectivity
研究了一系列不同取代的硝基苯并呋喃与异戊二烯和2,3-二甲基丁二烯的反应。正常电子需求产生的各种单加合物和二加合物已被鉴定并在结构上表征了狄尔斯-阿尔德缩合反应,涉及碳环的活化的C 6 C 7和/或C 4 C 5双键作为亲二烯体的贡献者。发现反应的区域选择性强烈依赖于该环的取代模式。在4-硝基-6-X系列中,如果X是强吸电子取代基(X = NO 2,SO 2),则二烯分子首先加至C 6 C 7双键。CF 3),但如果X是中度活化的取代基(X = CN,CF 3),则连接到硝基活化的C 4 C 5双键上。随后发生第二分子二烯的添加,以在6-氰基,6-三氟甲基和6-硝基系统中产生高度立体选择性的二加合物。与此行为相反,在4-X-6-硝基系列(X = CN,CF 3)中仅获得了对应于二烯加至硝基活化的C 6 C 7双键的单加合物。4,6-二硝基四唑[1,5- a]吡啶与4,6-二硝基苯并呋喃的反