Ultra-violet irradiation of 2,4-dichloro-1,3-diazaanthracene 2 or 2,4-dimethoxy-1,3-diazaanthracene 3 with cyclopentadiene yields single [4π+4π] cycloadducts, which can be transformed into the fused uracil and related pyrimidines by chemical modification of the chlorine or methoxy substituents; [4π+4π] head to head anti-dimers 17 and head to tail anti-dimers 19 are the exclusive products from solution
用
环戊二烯紫外线照射2,4-二
氯-1,3-二氮杂
蒽2或2,4-二甲氧基-1,3-二氮杂
蒽3产生单个[ 4π + 4π ]环加合物,可以将其转变为稠合的通过
化学修饰
氯或甲氧基取代基的尿
嘧啶和相关的
嘧啶;[ 4π + 4π ]头对头反二聚体17和头对尾反二聚体19是溶液辐照2或3的唯一产物,而只有反二聚体19 以固态形成。