that the reversibility of the dimerization reaction may be a factor in determining the regiochemistry and stereochemistry of the photodimers. A bisdehydro product prepared from the dimers of the dihydropyrone has been shown to undergo photocleavage to 2,6-dimethyl-4-pyrone, and it is proposed that reversibility may also be a factor affecting the course of the photodimerization of this pyrone.
                                    水溶液中 2,3-二氢-
2,6-二甲基-4-吡喃酮的紫外线照射导致
环丁烷类型的三个顺-反-顺光二聚体的区域特异性和立体选择性形成,即八氢-2, 7-8a,8b-tetramethylcyclobuta[1,2-b:4,3-b']dipyran-4,5-diones,其结构已通过
化学和光谱方法确定,包括对质子磁中核 Overhauser 效应的研究其中之一的频谱。二聚体经历光互变,并且有人提出该过程涉及到单体的光回复并且二聚反应的可逆性可能是决定光二聚体的区域
化学和立体
化学的一个因素。由二氢
吡喃酮的二聚体制备的双脱氢产物已被证明会发生光裂解为 
2,6-二甲基-4-吡喃酮,