On irradiation (λ = 350 nm) in neat hex-1-yne, naphthalene-1,2-dione monoacetals 1 afford mixtures of pentacyclic photodimers and up to 25% (isolated yield) of mixed photocycloadducts 2. Careful acidic hydrolysis of the acetal function of 2 gives the title compounds 3, the overall sequence representing a first approach to a (formal) [2 + 2] photocycloadduct of a 1,2-naphthoquinone to an alkyne.
在纯正的己-1-炔中照射(λ = 350 nm),1,2-
萘二酮单
缩醛1生成五环光二聚体混合物和多达25%(分离收率)的混合光环加成物2。对2的
缩醛功能进行仔细的酸性
水解可得到标题化合物3,整个序列代表了对
1,2-萘醌与炔之间的(正式的)[2 + 2]光环加成物的第一次尝试。