Zum photochemischen Verhalten von Sydnonen und 1,3,4‐Oxadiazolin‐2‐onen. 56. Mitteilung über Photoreaktionen

Abstract

On the Photochemistry of Sydnones and 1,3,4-0xadiazolin-2-ones SummaryThe photochemical behaviour of several 3,bdisubstituted sydnones (cf: Scheme 5) in dioxane solution was investigated. The pure sydnones give, as was already reported

Oxadiazoles

“…Alkenes and other trapping agents have been used to capture the dipolar nitrilimine [70][71][72]. When 1,3-butadiene was used as a dipolarophile, 1,3-diphenyl-5-vinylpyrazole (64) was obtained, so confirming that 60 is the trapped fragment (Scheme 13.22) [73].…”

3-(Phenylseleno)-2-propenal as a versatile unit for oxetane ring formation

“…This is in keeping with the thought that a two-step process involving multiple bond fissions to the same carbon (for example, loss of water followed by loss of HCO, or vice versa) would not dominate these spectra to the extent that it totally suppresses other well-known facile reactions (loss of acetic acid, loss of water, loss of butadiene). While the earlier workers8,10 noted that the loss of 47 mass units was characteristic of the 7,17-dione system, they did not refer to the evidence from the metastable ions which they recorded nor did they note the (5) Joaka, J.; Fajkos, J.; Sorm, F. Collect. Czech Chem.…”

1,3,4-Thiadiazoles of pharmacological interest: Recent trends in their synthesis via tandem 1,3-dipolar cycloaddition: Review

“…Several convenient methods have been reported for the generation of nitrilimines [25–39] . These include (i) thermolysis of either 2,5-disubstituted tetrazoles 1 , 1,3,4-oxadiazol-5-ones 2 or 1,2,3,4-oxathiadiazol-2-oxides 3 (ii) base treatment of either hydrazonoyl halides 4 , α-nitroaldehyde hydrazones 5 or N-hydrazonoyl pyridinium salts 6 (iii) oxidation of aldehyde hydrazones 7 with lead tetracetate or ferric chloride and (iv) treatment of acid hydrazides 8 with triphenylphosphine in acetonitrile ( Chart 1 ).…”