Table 6.
Calculated [M06-2X/6-31+G(d,p)] relative ZPE-corrected energy (kcal/mol) of the supramolecular complexes (SCs), TSs and adducts (ADs) located on the potential surfaces for the Diels–Alder reactions of the dienes 8b, 8c, 8g, 8j, 16a and 18a, and dienophiles 7b,c.a
 | |||||
| cycloaddends | SCb | TSb | ADb | diffc | 9/10 or 11b/20 (%)d (%)e (%)f |
| 8b/7c-endo | 0.00 (0.00) | 26.92 (29.72) | −9.76 (−6.47) | 0.00 (0.00) | 9f (99.4) (79.9) (76) |
| 8b/7c-exo | 0.76 (0.65) | 29.99 (30.53) | −7.94 (−7.31) | 3.07 (0.82) | 10f (0.6) (20.1) (24) |
| 8c/7b-endo | 0.00 (0.00) | 24.10 (26.21) | −12.99 (−10.79) | 0.00 (0.00) | 9g (99.9) (88.8) (99) |
| 8c/7b-exo | 2.96 (0.94) | 28.32 (27.44) | −10.44 (−11.12) | 4.22 (1.23) | 10g (0.1) (11.2) (1) |
| 8c/7c-endo | 0.00 (0.00) | 23.97 (26.20) | −10.31 (−7.66) | 0.00 (0.00) | 9h (100) (99.9) (99) |
| 8c/7c-exo | 5.40 (3.80) | 32.39 (31.58) | −5.38 (−6.62) | 8.42 (5.40) | 10h (0) (0.01) (1) |
| 8g/7c-endo | 0.00 (0.00) | 24.50 (26.83) | −9.60 (−6.55) | 0.00 (0.00) | 9m (100) (99.9) (91) |
| 8g/7c-exo | 4.25 (2.25) | 30.93 (30.81) | −6.41 (−6.98) | 6.43 (3.98) | 10m (0) (0.1) (9) |
| 8j/7c-endo | 0.00 (0.00) | 23.18 (25.49) | −11.22 (−9.62) | 0.00 (0.00) | 9p (99:9) (99.6) (99) |
| 8j/7c-exo | 3.11 (0.58) | 28.96 (28.82) | −9.02 (−9.28) | 5.77 (3.33) | 10p (0.1) (0.4) (1) |
| 16a/7c-endo | 0.00 (0.00) | 25.10 (26.70) | −7.72 (−6.22) | 0.00 (0.00) | 9c (100) (99.9) (94) |
| 16a/7c-exo | 3.70 (1.95) | 30.31 (31.05) | −6.90 (−6.22) | 5.21 (4.35) | 10c (0) (0.1) (6) |
| 18a/7c-endo | 0.00 (0.00) | 24.42 (26.68) | −6.25 (−5.24) | 0.00 (0.00) | 11b (100) (100) (91)g |
| 18a/7c-exo | 2.40 (2.07) | 34.14 (34.34) | −4.39 (−4.11) | 9.72 (7.66) | 20 (0) (0) (9)g |
aThe endo/exo TSs for each pair of cycloaddends lead to a mixture of adducts 9/10 or 11b/20, whose ratios are indicated in both rows of the pairs 8/7, 16a/7c or 18a/7c. bNumbers in parentheses correspond to relative Gibbs energy (kcal/mol). cEnergy differences for the TSs, relative to the most stable endo approach of the pairs 8/7, 16a/7c or 18a/7c. dPercentage ratio of the pairs 9/10 or 11b/20, calculated from the Boltzmann distribution (at 298 K) from the TSs obtained from the relative zero-point corrected energy. ePercentage ratio of the pairs 9/10 or 11b/20, calculated from the Boltzmann distribution (at 298 K) of the TSs obtained from the relative Gibbs energies. fPercentage ratio of the pairs 9/10 or 11b/20, determined from the experimental Diels–Alder cycloadditions (Table 2). gFor the ratio of 11b/20, see Scheme 6.