Table 2. 1H NMR Spectra of Compounds 8a-f and 13a-f
Com-
pound
Chemical shifts, , ppm (J, Hz)
8a
8b
8c
4.67 (2H, d, J = 5.3, NCH2); 5.10-5.25 (2H, m, CH=CH2); 5.75-5.95 (1H, m, CH=CH2);
6.95 (1H, d, J = 7.8, H-7'); 7.08 (1H, dd, J = 7.8, J = 7.8, H-6');
7.42 (1H, dd, J = 7.8, J = 7.8, H-5'); 8.79 (1H, d, J = 7.8, H-4'); 11.27 (1H, s, NH)
4.67 (2H, d, J = 5.1, NCH2); 5.21 (2H, dd, J = 5.4, J = 1.1, CH=CH2);
5.75-5.94 (1H, m, CH=CH2); 6.96 (1H, d, J = 8.4, H-7');
7.46 (1H, dd, J = 8.4, J = 2.1, H-6'); 8.50 (1H, d, J = 2.1, H-4'); 11.41 (1H, s, NH)
3.24 (3H, s, NCH3); 5.27 (2H, s, NCH2Fur); 6.35-6.45 (1H, m, H-4 Fur);
6.48 (1H, d, J = 3.3, H-3 Fur); 7.20 (1H, d, J = 8.2, H-7');
7.55-7.67 (2H, m, H-6', H-5 Fur); 8.85 (1H, d, J = 1.7, H-4')
8d
8e
2.33 (3H, s, NCH3); 5.30 (2H, s, NCH2Ph); 7.03 (1H, d, J = 7.5, H-7');
7.20-7.40 (6H, m, H Ph, H-6'); 8.66 (1H, s, H-4')
3.75 (3H, s, OCH3); 5.27 (2H, s, NCH2); 6.86 (1H, d, J = 8.6, H-7');
7.04 (1H, dd, J = 8.6, J = 2.5, H-6'); 7.21-7.43 (5H, m, H Ph); 8.46 (1H, d, J = 2.5, H-4');
11.08 (1H, s, NH)
8f
2.40 (3H, s, 5'-CH3); 3.26 (3H, s, NCH3); 5.36 (2H, s, NCH2Fur);
6.31 (1H, dd, J = 3.2, J = 1.9, H-4 Fur); 6.44 (1H, d, J = 3.2, H-3 Fur);
6.74 (1H, d, J = 7.9, H-7'); 7.20-7.30 (1H, m, H-6'); 7.32-7.37 (1H, m, H-5 Fur);
8.81 (1H, s, H-4')
13a
2.64 (3H, s, NCH3); 3.30 (1H, d, J = 10.4) and 3.69 (1H, d, J = 10.4, 2''-CH2);
3.47 (1H, d, J = 10.9) and 3.91 (1H, d, J = 10.9, 5''-CH2); 4.29-5.71 (2H, m, CH2СН=СН2);
5.10 (2H, dd, J = 17.5, J = 10.3, СН=CH2); 5.48-5.72 (1H, m, СH=СН2);
6.87 (1H, d, J = 7.4, H-7'); 6.93 (1H, dd, J = 7.4, J = 7.4, H-6');
7.15-7.30 (2H, m, H-4',5'); 8.68 (1H, s, NH)
13b
2.63 (3H, s, NCH3); 3.28 (1H, d, J = 10.4) and 3.66 (1H, d, J = 10.4, 2''-CH2);
3.46 (1H, d, J = 10.8) and 3.89 (1H, d, J = 10.8, 5''-CH2);
4.45 (1H, dd, J = 14.5, J = 6.3) and 4.61 (1H, dd, J = 14.5, J = 5.3, CH2СН=СН2);
5.15 (1H, d, J = 17.1) and 5.26 (1H, d, J = 10.1, СН=СH2); 5.54-5.73 (1H, m, СH=СН2);
6.75 (1H, d, J = 8.2, H-7'); 7.32 (1H, d, J = 1.9, H-4');
7.38 (1H, dd, J = 8.2, J = 1.9, H-6'); 7.89 (1H, s, NH)
13c
13d
2.62 (3H, s, 1''-CH3); 3.18 (1H, d, J = 10.4) and 3.70 (1H, d, J = 10.4, 2''-CH2);
3.18 (3H, s, 1'-CH3); 3.48 (1H, d, J = 10.7) and 3.90 (1H, d, J = 10.7, 5''-CH2);
5.05 (1H, d, J = 15.0) and 5.12 (1H, d, J = 15.0, NCH2Fur); 6.20-6.28 (2H, m, H-3,4 Fur );
6.72 (1H, d, J = 8.2, H-7'); 7.20-7.35 (3H, m, H-5 Fur, H-4',6')
2.61 (3H, s, 1''-CH3); 3.17 (1H, d, J = 10.6) and 3.67 (1H, d, J = 10.6, 2''-CH2);
3.19 (3H, s, 1'-CH3); 3.47 (1H, d, J = 10.6) and 3.89 (1H, d, J = 10.6, 5''-CH2);
5.00 (1H, d, J = 14.0) and 5.17 (1H, d, J = 14.0, NCH2Ph);
6.71 (1H, dd, J = 8.4, J = 4.2, H-7'); 6.87 (1H, dd, J = 8.1, J = 2.5, H-4');
6.95 (1H, dd. d, J = 8.4, J = 6.3, J = 2.5, H-6'); 7.12-7.32 (5H, m, Н Ph)
13e
13f
2.63 (3H, s, NCH3); 3.29 (1H, d, J = 10.3) and 3.66 (1H, d, J = 10.3, 2''-CH2);
3.46 (1H, d, J = 10.7) and 3.88 (1H, d, J = 10.7, 5''-CH2); 3.49 (3H, s, OCH3);
5.05 (1H, d, J = 14.4) and 5.12 (1H, d, J = 14.4, NCH2Ph); 6.65-6.80 (3H, m, H-4',6',7');
7.07-7.22 (5H, m, H Ph); 7.87 (1H, s, NH)
2.21 (3H, s, 5'-CH3); 2.63 (3H, s, 1''-CH3); 3.17 (1H, d, J = 10.4) and
3.71 (1H, d, J = 10.4, 2''-CH2); 3.18 (3H, s, 1'-CH3); 3.47 (1H, d, J = 10.7) and
3.92 (1H, d, J = 10.7, 5''-CH2); 5.06 (2H, s, NCH2Fur); 6.15 (1H, d, J = 3.2, H-3 Fur);
6.24 (1H, dd, J = 3.2, J = 1.9, H-4 Fur); 6.68 (1H, d, J = 7.7, H-7');
7.00-7.12 (2H, m, H-4',6'); 7.25-7.28 (1H, m, H-5 Fur)
Two chiral centers are formed as a result of the cycloaddition, so that formally four stereoisomers of
compound 13 may be formed – ((R,R), (R,S), (S,R), and (S,S)). However, since [3+2] cycloaddition is a
concerted process (not ionic), the chiral centers are formed simultaneously, which leads to the formation of only
1
two stereoisomers – the enantiomers (R,S) and (S,R). The absence in the H NMR spectra of signals for even
traces of the other two possible isomers ((R,R) and (S,S)) serves as an experimental confirmation of this.
As a result of the equal probability of addition of the azomethine ylide 12 to the enantiotopic faces of
the dipolarophile 8a (from above or below), a racemic mixture of the isomers (R,S)-13a and (S,R)-13a is
formed, as is also confirmed by the packing of the bis-spirocycle molecules in the unit cell, according to X-ray
crystallographic data.
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