1 Department of Chemical and Biochemical Engineering, Technical University of Denmark 2 CHEC Research Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark 3 University of Queensland
1-Azidophthalazine 9A is generated in trace amount by mild FVT of tetrazolo[5,1-a]phthalazine 9T and is observable by its absorption at 2121 cm-1 in the Ar matrix IR spectrum. Ar matrix photolysis of 9T/9A at 254 nm causes ring opening to generate two conformers of (o-cyanophenyl) diazomethane 11 (2079 and 2075 cm-1), followed by (o-cyanophenyl)carbene 312, cyanocycloheptatetraene 13, and finally cyano(phenyl)carbene 314 as evaluated by IR spectroscopy. The two carbenes 312 and 314 were observed by ESR spectroscopy (D|hc = 0.5078, E|hc = 0.0236 and D|hc = 0.6488, E|hc = 0.0195 cm-1, respectively). The rearrangement of 12 â., 13 â., 14 constitutes a carbene-carbene rearrangement. 1-Phthalazinylnitrene 310 is observed by means of its UV-vis spectrum in Ar matrix following FVT of 9 above 550 C. Rearrangement to cyanophenylcarbenes also takes place on FVT of 9 as evidenced by observation of the products of ring contraction, viz., fulvenallenes and ethynylcyclopentadienes 16-18. Thus the overall rearrangement 10 → 11 → 12 â., 13 â., 14 can be formulated. © 2013 American Chemical Society.
Journal of Organic Chemistry, 2014, Vol 79, Issue 1, p. 307-313
Organic Chemistry; Diazomethanes; ESR spectroscopy; IR spectrum; Phthalazines; Ring contraction; Ring opening; Trace amounts; UV-Vis spectrum; Absorption spectroscopy; Photolysis; Organic compounds; 1 phthalazinylnitrene; carbenoid; o cyanophenylcarbene; phenylcyanocarbene; phthalazine derivative; tetrazolo[5,1 a]phthalazine; unclassified drug; article; electron spin resonance; infrared spectroscopy; photolysis; reaction analysis; ring opening; ultraviolet spectroscopy
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