Long-lived 9-cyano-9,10-dimethylphenanthrenyl cation. Migration of cyano group in carbocations

Abstract

Long-lived 9-cyano-9,10-dimethylphenanthrenyl cation was generated in superacidic medium, and its structure was determined by 1 H and 13 C NMR spectroscopy. The energy barrier to 1,2-shift of the cyano group in 9-cyano-9,10-dimethylphenanthrenyl cation was estimated by NMR and DFT calculations.

Reaction of 10,10-dimethyl-9-trimethylsiloxy-9,10-dihydrophenanthrene-9-carbonitrile with acids

“…1 [2]. 13 C NMR spectrum (150.95 MHz), δ C , ppm: 28.8 (CH 3 ), 47.8 (C 9 ), 121.8 (C 10a ), 126.3 (C 4 ), 126.4 (C 4b , C 5 ), 127.3 (C 8 ), 129.8 (C 6 ), 131.0 (C 2 ), 132.5 (C 1 ), 133.8 (C 7 ), 142.6 (C 8a ), 148.2 (C 3 ), 149.0 (C 4a ), 216.9 (C 10 ).…”

“…9,9-Dimethyl-9,10-dihydrophenanthren-9-one (IV) in CF 3 COOH-CD 2 Cl 2 (4 : 1). 1 Nitrile I in CF 3 COOH-CD 2 Cl 2 (4 : 1). The 1 H and 13 C NMR spectra were identical to the corresponding spectra of a solution of ketone IV in CF 3 COOH-CD 2 Cl 2 (4 : 1) with the difference that signals from HCN {δ 4.32, δ C 108.0 ppm ( 1 J CH = 273 Hz); cf.…”

“…The temperature in the NMR probes was calibrated against melting point of pentane (-130°C) and using standard methanol sample (above -90°C); linear interpolation was applied for intermediate temperatures. Signals in the NMR spectra were assigned using two-dimensional 1 The synthesis of 10,10-dimethyl-9-trimethylsiloxy-9,10-dihydrophenanthrene-9-carbonitrile (I) was described in [1]. Ketone IV was prepared as reported in [10].…”

“…We found [1] that 10,10-dimethyl-9-trimethylsilyloxy-9,10-dihydrophenanthrene-9-carbonitrile (I) in superacid media undergoes ionization with formation of long-lived 9-cyano-9,10-dimethylphenanthrenyl cation (II) (Scheme 1). Apart from signals belonging to cation II, the NMR spectra contained a number of additional signals indicating other schemes of reactions of nitrile I with superacids.…”

“…Formamide, 0.02 g (0.4 mmol), was dissolved in 0.4 ml (4.5 mmol) of trifluoromethanesulfonic acid at room temperature, 0.1 ml of CD 2 Cl 2 was added, and NMR spectra of the solution were recorded at 32°C. 1 This study was performed under financial support by the Russian Foundation for Basic Research (project no. 09-03-00 116-a) and by the Chemistry and Materials Science Department of the Russian Academy of Sciences (proiect no.…”