Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108011876/su3020sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270108011876/su3020Isup2.hkl |
CCDC reference: 638788
(1S,2S)-trans-N,N'-Bis[1-(S)-phenylethyl]-1,2-diaminocyclohexane, (S,S,S,S)-(1) (18 mg, 2.2 mol%) (Anaya de Parrodi et al., 1998), diethylaniline (13 ml, 32 mol%), CDCl3 (0.5 ml) and PCl3 (4.6 M solution in CH2Cl2, 12 µl, 2.3 mol%) were placed with vigorous stirring in a NMR tube and the reaction was followed by 31P NMR. After 5 min, the chlorodiazaphospholidine was formed in situ. Immediately after phenol or naphthol were added to the reaction mixture with vigorous stirring, 31P NMR spectra were recorded, showing that the chiral phosphoramidites ligands (S,S,S,S)-(2a) or (S,S,S,S)-(2b) were produced. Phosphoramidites (S,S,S,S)-(2a) or (S,S,S,S)-(2b) were added direct from the NMR tube, without purification, to a solution of Cu(OAc)2 (7.7 mg, 1.7 mol%) in toluene (3 ml). The solution was stirred under N2 at 298 K for 30 min and then cooled to 273 K. Et2Zn (1.0 M solution in hexane, 3.8 ml, 3.8 mmol, 1.5 equivalents) and 2-cyclohexen-1-one, (3) (0.24 ml, 2.5 mmol, 1 equivalent), were added to the reaction mixture. After 5 h at 273 K, the reaction was quenched with aqueous NH4Cl and the mixture was extracted with CH2Cl2 (2 × 20 ml). The organic phases were combined, dried over Na2SO4, filtered and concentrated. The crude product was purified by column chromatography on deactivated silica gel (Et3N/SiO2, 2.5% v/v) with hexane as eluent, affording rac-3-ethylcyclohexanone, (4) (47 mg, 15%), a mixture of non-isolated oligomers, and rac-(I) as colourless crystals (48 mg, 6%), which were recrystallized from hexane–CH2Cl2 (10:1 v/v). Analytical data for rac-(I) are available in the archived CIF.
Hydroxyl H atom H3 was located in a difference Fourier map and refined freely, with O—H = 0.82 (2) Å. The remaining H atoms were included in calculated positions and treated as riding atoms, with C—H = 0.96–0.98 Å, and with Uiso(H) = 1.2 or 1.5Ueq(C).
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 2008); program(s) used to refine structure: SHELXTL-Plus (Sheldrick, 2008); molecular graphics: SHELXTL-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXTL-Plus (Sheldrick, 2008).
C20H30O3 | Z = 2 |
Mr = 318.44 | F(000) = 348 |
Triclinic, P1 | Dx = 1.232 Mg m−3 |
Hall symbol: -P 1 | Melting point = 457–459 K |
a = 8.6898 (10) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.2312 (12) Å | Cell parameters from 60 reflections |
c = 12.3633 (14) Å | θ = 4.7–15.2° |
α = 72.377 (11)° | µ = 0.08 mm−1 |
β = 73.574 (10)° | T = 298 K |
γ = 67.681 (9)° | Prism, colourless |
V = 858.41 (18) Å3 | 0.60 × 0.44 × 0.18 mm |
Bruker P4 diffractometer | Rint = 0.019 |
Radiation source: fine-focus sealed tube | θmax = 27.5°, θmin = 2.5° |
Graphite monochromator | h = −10→3 |
2θ/ω scans | k = −11→11 |
6729 measured reflections | l = −16→16 |
3878 independent reflections | 3 standard reflections every 97 reflections |
2728 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.042 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0445P)2 + 0.1781P] where P = (Fo2 + 2Fc2)/3 |
3878 reflections | (Δ/σ)max = 0.001 |
213 parameters | Δρmax = 0.21 e Å−3 |
0 restraints | Δρmin = −0.16 e Å−3 |
0 constraints |
C20H30O3 | γ = 67.681 (9)° |
Mr = 318.44 | V = 858.41 (18) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.6898 (10) Å | Mo Kα radiation |
b = 9.2312 (12) Å | µ = 0.08 mm−1 |
c = 12.3633 (14) Å | T = 298 K |
α = 72.377 (11)° | 0.60 × 0.44 × 0.18 mm |
β = 73.574 (10)° |
Bruker P4 diffractometer | Rint = 0.019 |
6729 measured reflections | 3 standard reflections every 97 reflections |
3878 independent reflections | intensity decay: 1% |
2728 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.042 | 0 restraints |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.21 e Å−3 |
3878 reflections | Δρmin = −0.16 e Å−3 |
213 parameters |
Experimental. Analytical data: m.p. 457–459 K; 1H NMR (200 MHz, CDCl3, δ, p.p.m.): 0.92 (t, 3H, 3J = 7 Hz), 1.25–1.44 (m, 5H), 1.60–2.00 (m, 11H), 2.04–2.38 (m, 8H), 2.45 (d, 1H, 3J = 6 Hz), 2.67–2.73 (m, 1H), 4.02 (d, 1H, 3J = 3 Hz); 13C NMR (50 MHz, CDCl3, δ, p.p.m.): 14.3 (CH3), 17.4 (CH2), 22.9 (CH2), 25.1 (CH2), 27.9 (CH2), 28.4 (CH2), 28.5 (CH2), 32.3 (CH2), 33.3 (CH2), 36.7 (CH), 37.4 (CH), 43.6 (CH2), 43.7 (CH2), 47.1 (CH), 47.6 (CH), 53.9 (CH), 61.2 (CH) 73.1 (C), 211.5 (CO), 215.7 (CO); IR (Film, cm-1) 3491.1, 2918.7, 2862.2, 1687.9; HRMS-FAB+ m/z found: 319.2275 [(MH)+; calculated 319.2273 for C20H31O3]. |
x | y | z | Uiso*/Ueq | ||
C1a | 0.24345 (17) | −0.02153 (16) | 0.86487 (11) | 0.0369 (3) | |
H1aA | 0.1628 | −0.0804 | 0.8839 | 0.044* | |
C1 | 0.31055 (18) | −0.05948 (17) | 0.97485 (11) | 0.0410 (3) | |
C2 | 0.4083 (2) | −0.23276 (18) | 1.01700 (14) | 0.0524 (4) | |
H2A | 0.3311 | −0.2950 | 1.0456 | 0.063* | |
H2B | 0.4581 | −0.2418 | 1.0808 | 0.063* | |
C3 | 0.5478 (2) | −0.30162 (18) | 0.92217 (15) | 0.0545 (4) | |
H3B | 0.6352 | −0.2518 | 0.9023 | 0.065* | |
H3C | 0.5987 | −0.4161 | 0.9499 | 0.065* | |
C4 | 0.4770 (2) | −0.27226 (17) | 0.81575 (14) | 0.0535 (4) | |
H4A | 0.3973 | −0.3307 | 0.8346 | 0.064* | |
H4B | 0.5687 | −0.3139 | 0.7556 | 0.064* | |
C4a | 0.38682 (18) | −0.09280 (16) | 0.76924 (12) | 0.0401 (3) | |
H4aA | 0.3340 | −0.0855 | 0.7066 | 0.048* | |
C5a | 0.50498 (17) | 0.00984 (15) | 0.71971 (11) | 0.0355 (3) | |
H5aA | 0.5614 | −0.0001 | 0.7812 | 0.043* | |
C5 | 0.64169 (18) | −0.04443 (17) | 0.61816 (12) | 0.0432 (3) | |
C6 | 0.7674 (2) | 0.0458 (2) | 0.57005 (14) | 0.0554 (4) | |
H6A | 0.8462 | 0.0068 | 0.5039 | 0.067* | |
H6B | 0.8314 | 0.0283 | 0.6282 | 0.067* | |
C7 | 0.6740 (2) | 0.22420 (19) | 0.53362 (13) | 0.0517 (4) | |
H7A | 0.7538 | 0.2833 | 0.5098 | 0.062* | |
H7B | 0.6232 | 0.2429 | 0.4681 | 0.062* | |
C8 | 0.5367 (2) | 0.28454 (18) | 0.63266 (13) | 0.0482 (4) | |
H8A | 0.4770 | 0.3975 | 0.6066 | 0.058* | |
H8B | 0.5890 | 0.2739 | 0.6955 | 0.058* | |
C8a | 0.40885 (16) | 0.19169 (15) | 0.67741 (10) | 0.0345 (3) | |
H8aA | 0.3600 | 0.2019 | 0.6120 | 0.041* | |
C9a | 0.26086 (16) | 0.26114 (15) | 0.77206 (10) | 0.0329 (3) | |
H9aA | 0.3112 | 0.2573 | 0.8349 | 0.039* | |
C9 | 0.16102 (18) | 0.43964 (16) | 0.72735 (11) | 0.0394 (3) | |
H9A | 0.2465 | 0.4902 | 0.6807 | 0.047* | |
C10 | 0.0514 (2) | 0.45491 (19) | 0.64449 (13) | 0.0497 (4) | |
H10A | −0.0165 | 0.5665 | 0.6231 | 0.060* | |
H10B | 0.1245 | 0.4225 | 0.5746 | 0.060* | |
C11 | −0.0654 (2) | 0.3530 (2) | 0.69696 (14) | 0.0543 (4) | |
H11A | −0.1274 | 0.3620 | 0.6398 | 0.065* | |
H11B | −0.1470 | 0.3926 | 0.7620 | 0.065* | |
C12 | 0.03526 (19) | 0.17706 (18) | 0.73761 (13) | 0.0472 (4) | |
H12A | 0.1087 | 0.1348 | 0.6713 | 0.057* | |
H12B | −0.0425 | 0.1159 | 0.7738 | 0.057* | |
C12a | 0.14246 (16) | 0.15644 (15) | 0.82361 (10) | 0.0355 (3) | |
C13 | 0.0632 (2) | 0.53367 (18) | 0.82315 (13) | 0.0511 (4) | |
H13A | −0.0401 | 0.5071 | 0.8595 | 0.061* | |
H13B | 0.1316 | 0.5006 | 0.8817 | 0.061* | |
C14 | 0.0184 (3) | 0.71386 (19) | 0.77799 (17) | 0.0670 (5) | |
H14A | −0.0418 | 0.7667 | 0.8408 | 0.101* | |
H14B | −0.0518 | 0.7477 | 0.7215 | 0.101* | |
H14C | 0.1202 | 0.7412 | 0.7431 | 0.101* | |
O1 | 0.28530 (15) | 0.04040 (13) | 1.02878 (9) | 0.0538 (3) | |
O2 | 0.64498 (15) | −0.14713 (14) | 0.57434 (9) | 0.0596 (3) | |
O3 | 0.01867 (13) | 0.21168 (12) | 0.92094 (9) | 0.0449 (3) | |
H3 | 0.075 (3) | 0.194 (3) | 0.9697 (18) | 0.082 (7)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1a | 0.0333 (7) | 0.0390 (7) | 0.0383 (7) | −0.0191 (6) | 0.0014 (6) | −0.0063 (5) |
C1 | 0.0353 (7) | 0.0462 (8) | 0.0365 (7) | −0.0174 (6) | 0.0009 (6) | −0.0039 (6) |
C2 | 0.0508 (9) | 0.0482 (8) | 0.0505 (8) | −0.0156 (7) | −0.0112 (7) | 0.0008 (7) |
C3 | 0.0444 (9) | 0.0376 (8) | 0.0682 (10) | −0.0110 (7) | −0.0043 (8) | −0.0022 (7) |
C4 | 0.0565 (10) | 0.0378 (7) | 0.0623 (10) | −0.0186 (7) | 0.0031 (8) | −0.0145 (7) |
C4a | 0.0412 (8) | 0.0401 (7) | 0.0411 (7) | −0.0174 (6) | −0.0016 (6) | −0.0122 (6) |
C5a | 0.0337 (7) | 0.0395 (7) | 0.0324 (6) | −0.0130 (6) | −0.0007 (5) | −0.0101 (5) |
C5 | 0.0360 (8) | 0.0478 (8) | 0.0387 (7) | −0.0075 (6) | −0.0031 (6) | −0.0110 (6) |
C6 | 0.0363 (8) | 0.0673 (10) | 0.0527 (9) | −0.0161 (7) | 0.0091 (7) | −0.0162 (8) |
C7 | 0.0434 (8) | 0.0646 (10) | 0.0423 (8) | −0.0272 (8) | 0.0074 (7) | −0.0071 (7) |
C8 | 0.0451 (8) | 0.0481 (8) | 0.0478 (8) | −0.0238 (7) | 0.0072 (7) | −0.0091 (6) |
C8a | 0.0334 (7) | 0.0392 (7) | 0.0297 (6) | −0.0154 (6) | 0.0007 (5) | −0.0074 (5) |
C9a | 0.0326 (7) | 0.0368 (6) | 0.0288 (6) | −0.0141 (5) | −0.0009 (5) | −0.0072 (5) |
C9 | 0.0387 (7) | 0.0381 (7) | 0.0366 (7) | −0.0138 (6) | −0.0005 (6) | −0.0058 (5) |
C10 | 0.0515 (9) | 0.0488 (8) | 0.0423 (8) | −0.0127 (7) | −0.0122 (7) | −0.0022 (6) |
C11 | 0.0458 (9) | 0.0629 (10) | 0.0545 (9) | −0.0165 (8) | −0.0197 (7) | −0.0050 (7) |
C12 | 0.0409 (8) | 0.0542 (9) | 0.0510 (8) | −0.0220 (7) | −0.0098 (7) | −0.0081 (7) |
C12a | 0.0299 (7) | 0.0415 (7) | 0.0317 (6) | −0.0141 (6) | 0.0018 (5) | −0.0072 (5) |
C13 | 0.0514 (9) | 0.0460 (8) | 0.0485 (8) | −0.0094 (7) | −0.0021 (7) | −0.0152 (7) |
C14 | 0.0693 (12) | 0.0490 (9) | 0.0761 (12) | −0.0119 (9) | −0.0037 (10) | −0.0229 (8) |
O1 | 0.0608 (7) | 0.0562 (6) | 0.0421 (6) | −0.0144 (5) | −0.0102 (5) | −0.0131 (5) |
O2 | 0.0622 (7) | 0.0631 (7) | 0.0526 (6) | −0.0159 (6) | 0.0028 (5) | −0.0299 (5) |
O3 | 0.0342 (5) | 0.0514 (6) | 0.0390 (5) | −0.0135 (5) | 0.0055 (4) | −0.0077 (4) |
C1a—C1 | 1.5220 (19) | C8—C8a | 1.5371 (19) |
C1a—C12a | 1.5427 (18) | C8—H8A | 0.9700 |
C1a—C4a | 1.5486 (18) | C8—H8B | 0.9700 |
C1a—H1aA | 0.9800 | C8a—C9a | 1.5527 (17) |
C1—O1 | 1.2160 (17) | C8a—H8aA | 0.9800 |
C1—C2 | 1.505 (2) | C9a—C9 | 1.5516 (17) |
C2—C3 | 1.520 (2) | C9a—C12a | 1.5526 (17) |
C2—H2A | 0.9700 | C9a—H9aA | 0.9800 |
C2—H2B | 0.9700 | C9—C10 | 1.529 (2) |
C3—C4 | 1.516 (2) | C9—C13 | 1.5399 (19) |
C3—H3B | 0.9700 | C9—H9A | 0.9800 |
C3—H3C | 0.9700 | C10—C11 | 1.523 (2) |
C4—H4A | 0.9700 | C10—H10A | 0.9700 |
C4—H4B | 0.9700 | C10—H10B | 0.9700 |
C4a—C5a | 1.5359 (18) | C11—C12 | 1.527 (2) |
C4a—C4 | 1.543 (2) | C11—H11A | 0.9700 |
C4a—H4aA | 0.9800 | C11—H11B | 0.9700 |
C5a—C5 | 1.5244 (18) | C12—C12a | 1.529 (2) |
C5a—C8a | 1.5620 (18) | C12—H12A | 0.9700 |
C5a—H5aA | 0.9800 | C12—H12B | 0.9700 |
C5—O2 | 1.2143 (17) | C12a—O3 | 1.4450 (15) |
C5—C6 | 1.505 (2) | C13—C14 | 1.516 (2) |
C6—C7 | 1.522 (2) | C13—H13A | 0.9700 |
C6—H6A | 0.9700 | C13—H13B | 0.9700 |
C6—H6B | 0.9700 | C14—H14A | 0.9600 |
C7—C8 | 1.522 (2) | C14—H14B | 0.9600 |
C7—H7A | 0.9700 | C14—H14C | 0.9600 |
C7—H7B | 0.9700 | O3—H3 | 0.82 (2) |
C1—C1a—C12a | 114.97 (11) | C8a—C8—H8B | 109.2 |
C1—C1a—C4a | 110.45 (11) | H8A—C8—H8B | 107.9 |
C12a—C1a—C4a | 113.36 (10) | C8—C8a—C9a | 112.40 (11) |
C1—C1a—H1aA | 105.7 | C8—C8a—C5a | 109.11 (11) |
C12a—C1a—H1aA | 105.7 | C9a—C8a—C5a | 112.35 (10) |
C4a—C1a—H1aA | 105.7 | C8—C8a—H8aA | 107.6 |
O1—C1—C2 | 120.64 (14) | C9a—C8a—H8aA | 107.6 |
O1—C1—C1a | 123.57 (13) | C5a—C8a—H8aA | 107.6 |
C2—C1—C1a | 115.77 (13) | C9—C9a—C12a | 111.77 (11) |
C1—C2—C3 | 112.04 (12) | C9—C9a—C8a | 111.93 (10) |
C1—C2—H2A | 109.2 | C12a—C9a—C8a | 111.41 (10) |
C3—C2—H2A | 109.2 | C9—C9a—H9aA | 107.1 |
C1—C2—H2B | 109.2 | C12a—C9a—H9aA | 107.1 |
C3—C2—H2B | 109.2 | C8a—C9a—H9aA | 107.1 |
H2A—C2—H2B | 107.9 | C10—C9—C13 | 113.33 (12) |
C4—C3—C2 | 110.52 (13) | C10—C9—C9a | 110.94 (11) |
C4—C3—H3B | 109.5 | C13—C9—C9a | 114.29 (11) |
C2—C3—H3B | 109.5 | C10—C9—H9A | 105.8 |
C4—C3—H3C | 109.5 | C13—C9—H9A | 105.8 |
C2—C3—H3C | 109.5 | C9a—C9—H9A | 105.8 |
H3B—C3—H3C | 108.1 | C11—C10—C9 | 112.58 (12) |
C3—C4—C4a | 112.74 (12) | C11—C10—H10A | 109.1 |
C3—C4—H4A | 109.0 | C9—C10—H10A | 109.1 |
C4a—C4—H4A | 109.0 | C11—C10—H10B | 109.1 |
C3—C4—H4B | 109.0 | C9—C10—H10B | 109.1 |
C4a—C4—H4B | 109.0 | H10A—C10—H10B | 107.8 |
H4A—C4—H4B | 107.8 | C10—C11—C12 | 111.00 (13) |
C5a—C4a—C4 | 114.38 (12) | C10—C11—H11A | 109.4 |
C5a—C4a—C1a | 109.54 (10) | C12—C11—H11A | 109.4 |
C4—C4a—C1a | 110.21 (11) | C10—C11—H11B | 109.4 |
C5a—C4a—H4aA | 107.5 | C12—C11—H11B | 109.4 |
C4—C4a—H4aA | 107.5 | H11A—C11—H11B | 108.0 |
C1a—C4a—H4aA | 107.5 | C11—C12—C12a | 111.74 (12) |
C5—C5a—C4a | 112.83 (11) | C11—C12—H12A | 109.3 |
C5—C5a—C8a | 107.06 (10) | C12a—C12—H12A | 109.3 |
C4a—C5a—C8a | 113.03 (11) | C11—C12—H12B | 109.3 |
C5—C5a—H5aA | 107.9 | C12a—C12—H12B | 109.3 |
C4a—C5a—H5aA | 107.9 | H12A—C12—H12B | 107.9 |
C8a—C5a—H5aA | 107.9 | O3—C12a—C12 | 103.79 (11) |
O2—C5—C6 | 121.63 (13) | O3—C12a—C1a | 108.39 (10) |
O2—C5—C5a | 122.93 (14) | C12—C12a—C1a | 111.59 (11) |
C6—C5—C5a | 115.32 (12) | O3—C12a—C9a | 110.31 (10) |
C5—C6—C7 | 109.57 (13) | C12—C12a—C9a | 111.07 (11) |
C5—C6—H6A | 109.8 | C1a—C12a—C9a | 111.38 (10) |
C7—C6—H6A | 109.8 | C14—C13—C9 | 112.72 (13) |
C5—C6—H6B | 109.8 | C14—C13—H13A | 109.0 |
C7—C6—H6B | 109.8 | C9—C13—H13A | 109.0 |
H6A—C6—H6B | 108.2 | C14—C13—H13B | 109.0 |
C8—C7—C6 | 110.78 (12) | C9—C13—H13B | 109.0 |
C8—C7—H7A | 109.5 | H13A—C13—H13B | 107.8 |
C6—C7—H7A | 109.5 | C13—C14—H14A | 109.5 |
C8—C7—H7B | 109.5 | C13—C14—H14B | 109.5 |
C6—C7—H7B | 109.5 | H14A—C14—H14B | 109.5 |
H7A—C7—H7B | 108.1 | C13—C14—H14C | 109.5 |
C7—C8—C8a | 112.19 (12) | H14A—C14—H14C | 109.5 |
C7—C8—H8A | 109.2 | H14B—C14—H14C | 109.5 |
C8a—C8—H8A | 109.2 | C12a—O3—H3 | 104.2 (15) |
C7—C8—H8B | 109.2 | ||
C12a—C1a—C1—O1 | 1.35 (19) | C4a—C5a—C8a—C9a | 53.13 (14) |
C4a—C1a—C1—O1 | 131.18 (14) | C8—C8a—C9a—C9 | 59.13 (15) |
C12a—C1a—C1—C2 | 179.54 (11) | C5a—C8a—C9a—C9 | −177.33 (11) |
C4a—C1a—C1—C2 | −50.62 (15) | C8—C8a—C9a—C12a | −174.89 (11) |
O1—C1—C2—C3 | −130.50 (15) | C5a—C8a—C9a—C12a | −51.36 (14) |
C1a—C1—C2—C3 | 51.24 (18) | C12a—C9a—C9—C10 | −52.52 (14) |
C1—C2—C3—C4 | −52.43 (18) | C8a—C9a—C9—C10 | 73.26 (14) |
C1—C1a—C4a—C5a | −75.14 (13) | C12a—C9a—C9—C13 | 77.12 (15) |
C12a—C1a—C4a—C5a | 55.54 (15) | C8a—C9a—C9—C13 | −157.11 (12) |
C1—C1a—C4a—C4 | 51.54 (15) | C13—C9—C10—C11 | −76.11 (16) |
C12a—C1a—C4a—C4 | −177.78 (12) | C9a—C9—C10—C11 | 54.03 (16) |
C2—C3—C4—C4a | 56.80 (17) | C9—C10—C11—C12 | −55.92 (18) |
C5a—C4a—C4—C3 | 67.15 (16) | C10—C11—C12—C12a | 56.32 (17) |
C1a—C4a—C4—C3 | −56.78 (17) | C11—C12—C12a—O3 | 63.25 (14) |
C4—C4a—C5a—C5 | 60.37 (16) | C11—C12—C12a—C1a | 179.77 (11) |
C1a—C4a—C5a—C5 | −175.35 (11) | C11—C12—C12a—C9a | −55.28 (15) |
C4—C4a—C5a—C8a | −177.98 (11) | C1—C1a—C12a—O3 | −48.79 (14) |
C1a—C4a—C5a—C8a | −53.69 (14) | C4a—C1a—C12a—O3 | −177.18 (11) |
C4a—C5a—C5—O2 | 7.1 (2) | C1—C1a—C12a—C12 | −162.48 (11) |
C8a—C5a—C5—O2 | −117.90 (15) | C4a—C1a—C12a—C12 | 69.13 (14) |
C4a—C5a—C5—C6 | −176.77 (12) | C1—C1a—C12a—C9a | 72.75 (13) |
C8a—C5a—C5—C6 | 58.26 (16) | C4a—C1a—C12a—C9a | −55.64 (15) |
O2—C5—C6—C7 | 119.32 (16) | C9—C9a—C12a—O3 | −61.09 (13) |
C5a—C5—C6—C7 | −56.89 (17) | C8a—C9a—C12a—O3 | 172.85 (10) |
C5—C6—C7—C8 | 53.52 (18) | C9—C9a—C12a—C12 | 53.44 (14) |
C6—C7—C8—C8a | −57.22 (18) | C8a—C9a—C12a—C12 | −72.62 (14) |
C7—C8—C8a—C9a | −175.63 (12) | C9—C9a—C12a—C1a | 178.50 (10) |
C7—C8—C8a—C5a | 59.05 (16) | C8a—C9a—C12a—C1a | 52.44 (14) |
C5—C5a—C8a—C8 | −56.67 (14) | C10—C9—C13—C14 | −71.18 (18) |
C4a—C5a—C8a—C8 | 178.48 (11) | C9a—C9—C13—C14 | 160.39 (14) |
C5—C5a—C8a—C9a | 177.98 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1 | 0.82 (2) | 2.01 (2) | 2.7081 (16) | 143 (2) |
C8a—H8aA···O2i | 0.98 | 2.52 | 3.4381 (18) | 156 |
Symmetry code: (i) −x+1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C20H30O3 |
Mr | 318.44 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 298 |
a, b, c (Å) | 8.6898 (10), 9.2312 (12), 12.3633 (14) |
α, β, γ (°) | 72.377 (11), 73.574 (10), 67.681 (9) |
V (Å3) | 858.41 (18) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.60 × 0.44 × 0.18 |
Data collection | |
Diffractometer | Bruker P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6729, 3878, 2728 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.119, 1.05 |
No. of reflections | 3878 |
No. of parameters | 213 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.21, −0.16 |
Computer programs: XSCANS (Siemens, 1996), SHELXTL-Plus (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1 | 0.82 (2) | 2.01 (2) | 2.7081 (16) | 143 (2) |
C8a—H8aA···O2i | 0.98 | 2.52 | 3.4381 (18) | 156 |
Symmetry code: (i) −x+1, −y, −z+1. |
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Perhydrotriphenylene (C18H36, abbreviated PHTP hereinafter) has a complex stereochemistry. There are six enantiomeric pairs and four meso-forms, as determined by Farina & Audisio (1970a). These authors were able to resolve into antipodes the highly symmetrical isomer belonging to the D3 point group, in which all rings have a chair conformation and all fused-ring junctions have a trans configuration (Farina & Audisio, 1970b). Following Farina's nomenclature, the D3 isomer may be described as anti-trans-anti-trans-anti-trans, shortened ATATAT. Descriptors trans apply to endo C—C bonds of the central ring (bonds shared by two cycles), while anti descriptors are for C—C exo bonds.
Racemic D3-PHTP has been characterized crystallographically (Harlow & Desiraju, 1990). This isomer generally forms inclusion compounds with small organic molecules (König et al., 1997). In most cases, crystallographic studies of PHTP clathrates are severely complicated due to a tendency to disorder, with diffraction patterns including incommensurate satellites (Weber et al., 2001; Bürgi et al., 2005). For these reasons, very few PHTP derivatives have been characterized in the solid state. On the other hand, to the best of our knowledge, the possibility of stabilizing other isomers of PHTP has not been addressed, neither through accurate ab initio calculations nor by crystallizing such isomers.
The matter may be probed, at least partially, through the synthesis of PHTP derivatives, provided that the starting materials do not include fused rings. With the exception of the above-mentioned naked D3-PHTP, only one guest-free PHTP derivative has been characterized crystallographically to date, namely 9-benzyl-12a-hydroxytetradecahydrotriphenylene- 1,5(2H,4bH)dione. This derivative was synthesized (Blake et al., 2007) through an original triple cascade reaction involving two Michael additions followed by an intramolecular aldol reaction. The main difficulty for their X-ray study was due to the very small size of the single crystals available (0.08 × 0.01 × 0.01 mm).
During our work on the copper-catalyzed conjugate addition of Et2Zn to enones in the presence of chiral phosphoramidites (Feringa, 2000), we found that 2-cyclohexen-1-one, (3), behaves as expected, affording 3-ethylcyclohexanone, (4), but a by-product, the title compound, rac-(I), was also produced in a low 6% yield (see Scheme 1 and Experimental). Analytical data indicated that (I) is the 9-ethyl analogue of Blake and co-workers' functionalized PHTP. In fact, these authors also detected (I) in their oligomeric mixture, but were unable to isolate it as a pure crystalline solid. We surmise that the formation of rac-(I) under our conditions occurred by trapping the enolate of 3-ethylcyclohexanone with 2-cyclohexen-1-one, which afforded the enolate of trans-3-ethyl-2-(3-hydroxycyclohex-2-enyl)cyclohexanone. This step was followed by a Michael addition reaction with another equivalent of 2-cyclohexen-1-one, and finally the ring closure proceeded by an aldol reaction, leading to a functionalized-PHTP enolate. Protonation finally afforded the title alcohol, rac-(I).
The molecular strcture of compound (I) is illustrated in Fig. 1. The relative stereochemistry at the six chiral C atoms of the central A ring is 1aRS,4aRS,5aSR,8aRS,9aRS,12aSR. This configuration corresponds to ring junctions trans-cis-cis for A/C, A/B and A/D, respectively (Scheme 2 and Fig. 1). All the exo central C—C bonds are anti. All six-membered rings have chair conformations, with small deviations from ideal geometry, which can be attributed to polycyclic strain [θ puckering parameters (Cremer & Pople, 1975) 177.67 (16), 5.31 (18), 176.33 (17) and 1.36 (17)° for rings A, B, C and D, respectively]. Assuming ideal chair conformations for rings A–D, the PHTP core structure of rac-(I) corresponds to the rac-ATACAC isomer in Farina's nomenclature, and belongs to point group C2.
Interestingly, Blake et al. isolated a third isomer for the core PHTP structure, namely meso-STACAT, which includes a syn C8a—C9a exo bond and a trans C9a—C12a A/D ring junction (Scheme 2). The central A ring has a twist-boat conformation (θ = 89.9° and ϕ = 146.3°) as does ring B (θ = 85.9° and ϕ = 153.6°). The other peripheral rings have distorted chair conformations (ring C, θ = 167.5°; ring D, θ = 169.4°). The PHTP nucleus of this isomer approximates a Cs symmetry, assuming ideal boat and chair conformations. However, considering departures from ideal geometry, the actual symmetry is rather C1 and the molecule is not a true meso form.
As discussed above, a reasonable assumption is that both C2 and Cs isomers are produced following identical routes. The stabilization of different isomers should then be related to the nature of the functional group at C9 rather than to the reaction conditions. If the proposed tandem mechanism is correct, the differentiation takes place during the first Michael addition, forming the C8a—C9a bond. In the case of 3-benzylcyclohexanone enolate addition, a syn–exo C—C bond is formed. The benzyl group is then equatorial, avoiding 1,3-diaxial interactions. With the ethyl analogue, the opposite enolate enantiomer is more favourably added, leading to an axially oriented ethyl group. The second Michael addition, forming the C4a—C5a bond and the final ring closure, is identical regardless of the substituent at C9. In both cases, it seems that the aldol reaction, forming the C1a—C12a bond, is assisted by the formation of a weak intramolecular hydrogen bond involving the hydroxy and carbonyl functional groups at C12a and C1, respectively. Other non-covalent interactions seem to have very little influence on the observed structure. For (I), the crystal packing features centrosymmetric dimers formed through weak C═O···H hydrogen bonds (Table 1). NMR data (COSY and HSQC) are consistent with the configuration observed in the solid state. We thus consider that the stereochemistry of (I) is induced by the Zn catalyst formed in situ, and not by intermolecular interactions in the solid state.
In conclusion, we propose that the MiMiRC tandem reaction (Mi = Michael addition; RC = ring closure) may be extended to libraries of substituted enones, allowing new stereoisomers of PHTP derivatives to be stabilized. By using suitable easily removable functional groups, new pure or racemic PHTP stereoisomers would then be achievable.