Wavelength-dependent photochemistry of Diazo Meldrum's acid and its spirocyclic isomer, Diazirino Meldrum's acid: Wolff rearrangement versus isomerization.
Photoreaction of diazo Meldrum's acid (1) shows a unique wavelength selectivity. At 254 nm it results in efficient (phi(254) = 0.34) Wolff rearrangement, while irradiation with 355 nm light leads to a completely different process, isomerization into corresponding cyclic alpha,alpha"-dicarbonyl diazirine 2 (phi(350) = 0.024). UV photolysis of diazirine 2 is accompanied by two competing processes: loss of nitrogen followed by the Wolff rearrangement and isomerization into diazo compound 1. Thermal decomposition of 1 leads to clean Wolff rearrangement, while heating of 2 causes quantitative conversion into diazo isomer 1.
Bogdanova
Aneta
A
Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
Popik
Vladimir V
VV
D001391:Azo Compounds / Q000737:chemistry*; D003978:Diazomethane / Q000737:chemistry; D004146:Dioxanes / Q000737:chemistry*; D007536:Isomerism; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet
D001391:Azo Compounds; D004146:Dioxanes; D003978:Diazomethane; C076489:Meldrum's acid