Reductive methylation decacyclene

DECACYCLENE CHEMISTRY. Unlike perylene, which consumes 2 mol of K per mole of perylene, decacyclene consumes between 2.2 and 3.0 mol of K per mole of decacyclene. As with perylene, we wanted to determine if reductive methylation could yield a product with a methyl group on a quaternary carbon, as in the C-3/C-q dimethyldihydrodecacyclene isomer depicted in Scheme III. 

Scheme III. The reductive methylation of decacyclene illustrated for hypothetical C-3/C-q dimethyldihydrodecacyclene product.

Inspection of the reductively methylated, hexylated, and octylated de-cacylenes shows evidence only for the broad Debye peaks no hydrocarbon material in the product gave Bragg peaks (e.g., as found in the initial decacyclene). The reductively methylated decacyclene showed a peak at 5.9 A of full width at half maximum of 3.3°20 on top of a much broader peak. The reductively hexylated material showed peaks at 4.0 A (major) and 5.3 A (minor). 

The reduction of three polynuclear aromatic compounds, namely, perylene, decacyclene, and dibenzothiophene, with potassium metal in tetrahydrofuran at 25 °C, followed by quenching with alkyl iodides, was investigated. With perylene, a dianion was obtained, which on reaction with methyl iodide added two methyl groups the main re-gioisomer had one methyl group on C-l and one methyl group on the adjacent nonprotonated carbon, C-14. The reductive alkylation of decacyclene also led to alkyl groups on quaternary carbon atoms. The reduction of dibenzothiophene led to a loss of sulfur and proton uptake from solvent to yield biphenyl as the product after 24 h of reduction. 

LIQUID-STATE 13C NMR OF OTHER MATERIALS. We report results of 13C NMR of a di[2H3]methyldihydroperylene product for comparison with work on reductively alkylated decacyclene reported later. The two rehybridized carbons, namely, C-l and C-q, appeared at 8 38.6 and 41.7 respectively. The two methyl carbons, which are split by C-D coupling of 19.5 Hz, appeared at 8 14.6 and 33.0. Several aromatic resonances spanned the range from 8 119.0 to 141.6 (13C NMR data at an observation frequency of 100.4 MHz). 

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