Nitrene-Carbene-Carbene Rearrangement. Photolysis and Thermolysis of Tetrazolo[5,1-a]phthalazine with Formation of 1-Phthalazinylnitrene, o-Cyanophenylcarbene, and Phenylcyanocarbene

作者：Hoj Martin; Kvaskoff David; Wentrup Curt^*

来源：Journal of Organic Chemistry, 2014, 79(1): 307-313.

DOI：10.1021/jo402448u

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 (3)12, cyanocycloheptatetraene 13, and finally cyano(phenyl)carbene (3)14 as evaluated by IR spectroscopy. The two carbenes (3)12 and (3)14 were observed by ESR spectroscopy (D vertical bar hc = 0.5078, E vertical bar hc = 0.0236 and D vertical bar hc = 0.6488, E vertical bar hc = 0.0195 cm(-1), respectively). The rearrangement of 12 reversible arrow 13 reversible arrow 14 constitutes a carbene carbene-rearrangement. 1-Phthalazinylnitrene (3)10 is observed by means of its UV-vis spectrum in Ar matrix following FVT of 9 above 550 degrees 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 reversible arrow 13 reversible arrow 14 can be formulated.

• 出版日期2014-1-3