Irradiation of styryl-4-pyrones 1a-1d or 2a-2e (6-9 × 10−3 M, methanol solution) with filtered (RAYONET photochemical reactor, 300 nm) or unfiltered uv-light (high-pressure mercury arc lamp) under aerobic conditions led mainly to dimeric products. Parent 5-hydroxy-substituted compounds 1a-1d yielded exclusively “half-cage” dimers 3a-d characteristic for 4-pyrone dimerization. 5-Methoxy-analogues 2a-2e
用已过滤的(RAYONET光
化学反应器,300 nm)或未过滤的紫外光(高压
汞弧灯)照射
苯乙烯基-4-
吡喃酮1a-1d或2a-2e(6-9×10 -3 M,
甲醇溶液)在有氧条件下主要产生二聚体产物。母体5-羟基取代的化合物1a-1d仅产生4-
吡喃二聚化的“半笼”二聚体3a-d。5-甲氧基类似物2a-2e的行为类似于典型的
二苯乙烯结构,四取代的
环丁烷4和5的混合物与少量的
菲类化合物6是辐照的唯一可分离产物。产物的结构阐明是基于使用COSY,A
PT,HETCOR,HMBC和NOESY技术从MS,IR,1 H NMR和13 C NMR光谱获得的光谱数据。