Synthesis of optically active spiro homo- and methanofullerenes

Homo‐ and methano[60]fullerenes with chiral attached moieties – 1H and 13C NMR chemical shift assignments and diastereotopicity effects

“…This difference Figure 2. Experimental (abscissa axis) [26] and calculated in this study (ordinate axis) 13 C NMR chemical shift correlation of the homofullerene 1; maximum absolute deviation = 3.61 ppm, R 2 = 0.97, root mean square = 0.59 and a = 1.00. does not exceed 0.50 ppm for the other carbon atoms. Thus, the greatest substituent influence on a fullerene cage in the compound 1 is observed in the δ-environment relative to the carbon atoms of the substituent addition site (C-3/C-4).…”

“…The [5,6]-opened adduct 1 [26] is generated by the interaction between the (2S,5R)-1-diazo-2-isopropyl-5-methylcyclohexane and C 60 fullerene (Scheme 1).…”

“…[26] The 1 H and 13 C NMR assignments of compound 1 were performed by means of 2D NMR technique and are given in Table 1. Thus, the carbon resonance at δ C = 22.67 ppm correlates with the proton resonances at δ H = 2.16 (m) and 2.40 ppm (m) and the 13 C resonance at δ C = 25.56 ppm with the 1 H signals at δ H = 1.37 ppm (m), whereas the 13 C resonance at δ C = 29.63 ppm correlates with the peaks at δ H = 1.46 and δ H = 1.68 ppm in the HSQC spectrum, which then were assigned to the 3'-, 4'-and 6'-methylene groups of the cyclohexane ring, respectively.…”

“…[26] Forty fullerene signals are observed in the 13 C NMR spectrum of the methanofullerene 2 (Fig. 4) .05 and 151.35 ppm) were assigned to the C-10, C-8, C-5 and C-2, respectively, situated in the a-environment relative to the site addition C-1/C-9 carbon atoms, whereas the lowest frequency chemical shifts (δ C = 136.60, 136.73, 138.02 and 138.09 ppm) were attributed to the C-12, C-7, C-6 and C-11, respectively (Fig.…”

“…The reaction of C 60 fullerene and 1-diazo-2,7,7-trimethylbicyclo [2.2.1]heptane (Scheme 3) produced the [5,6]-opened adduct 3 as sole product [26] in which the 6'-methylene group is located above the fullerene pentagonal ring, and the methyl group at the C-2' atom is positioned above the fullerene hexagonal plane. (δ C = 62.89, 56.57 and 50.47 ppm were assigned to the quaternary carbon atoms C-2', C-1' and C-7', respectively.…”