Comparative photolysis of tetramethylcyclobutane-1,3-dione and 2,2,4-trimethyl-3-hydroxy-3-pentenoic acid, β-lactone in methanole

Photochemistry of dimethylthioketene dimers

“…In the case of 1,3-diketone 1 (S = 0) and the corresponding /3-lactone 2 (S = 0), no evidence for the formation of a carbene intermediate is reported. 7 In summary, we have established the occurrence of Norrish type I -cleavage in thiocarbonyl compounds.8,9 A detailed understanding of the mechanism of the above reactions and a study of related thiocarbonyl systems await our further investigation.…”

“…Interestingly, the photochemical behavior of 1 and 2 is different from that of the corresponding carbonyl compounds. 7 The diradical derived from analogous oxygenated compounds either eliminates carbon monoxide or cleaves to give dimethylketene, whereas evidence for like products are not to be seen in 1 and 2. In the case of 1,3-diketone 1 (S = 0) and the corresponding /3-lactone 2 (S = 0), no evidence for the formation of a carbene intermediate is reported.…”

Photolysis of Saturated Four‐Membered Rings with Two Exocyclic Double Bonds: A Photoextrusion Route to (Hetero)Methylenecyclopropanes

“…11). They can be interpreted in terms of [ 32 as the primary photo processes/":" Thus, in striking contrast to monocyclic 1,3cyclobutanediones, the bisspiro-I,3-cyclobutanediones 25b and 25d provided the first examples for the aoxacarbene rearrangement in this series." Release of strain is probably the driving force for the ring-opening of 25a to the 13 -ketoester 37a by solvolysis in methanol via a dark reaction."…”