SN1 Solvolysis Reactions
FULL PAPER
1H), 1.89–1.86 (m, 1H), 1.81 (m, 3H), 1.75 (s, 3H), 1.64–1.60 ppm (m,
1H); 13C NMR (CDCl3, 100 MHz): d=149.2, 134.3, 125.3, 109.0, 68.5,
36.7, 35.2, 31.0, 20.9, 20.8 ppm.
Acknowledgements
This work was financially supported by The National Natural Science
Foundation of China (20772065 and 21072098) and Program for New
Century Excellent Talents in University. We thank Prof. Xiao-Qing Zhu,
Prof. Chi Zhang, and Dr. Yan-Liang Liang at Nankai University for help-
ful discussions.
(S)-(À)-2-Methyl-5-(propan-2-ylidene)cyclohex-2-enol 5:[35] colorless oil.
GC analysis: Beta DEX 120 column (30 mꢁ0.25 mmꢁ0.25 mm film thick-
ness), flow rate 20 cmsecÀ1, T=808C for 1 min, 1 degminÀ1 to 2208C,
tR =51.2 min; [a]2D0 =À79.4 (c=1, CHCl3); 1H NMR (CDCl3, 400 MHz):
d=5.50 (s, 1H), 4.00 (s, 1H), 2.88 (m, 1H), 2.67 (m, 2H), 2.34 (m, 1H),
1.78 (s, 3H), 1.75 (s, 3H), 1.43 ppm (brs, 3H); 13C NMR (CDCl3,
100 MHz): d=135.9, 125.8, 124.3, 123.2, 70.4, 35.9, 29.8, 20.4, 20.2,
19.9 ppm.
[1] For reviews and books, see: a) M.-O. Simon, C.-J. Li, Chem. Soc.
301; d) I. T. Horvꢃth, Green Chem. 2008, 10, 1024; e) I. T. Horvꢃth,
P. T. Anastas, Chem. Rev. 2007, 107, 2167; f) A. S. Matlack, Introduc-
tion to Green Chemistry, Marcel Dekker, New York, 2001; g) P. T.
Anastas, L. G. Heine, (Eds. T. C. Williamson) Green Chemical Syn-
theses and Processes, American Chemical Society, Washington, DC,
2000; h) P. T. Anastas, T. C. Williamson, Green Chemistry: Frontiers
in Benign Chemical Syntheses and Processes, Oxford University
Press, Oxford, 1998.
[2] For reviews and books, see: a) M. J. Climent, A. Corma, S. Iborra,
U. M. Lindstrçm), Blackwell, Oxford, UK, 2007; g) L. Chen, C.-J.
3095; i) P. A. Grieco, Organic Synthesis in Water, Blackie Academic
and Professional, London, 1998; j) C.-J. Li, T.-H. Chan, Organic Re-
actions in aqueous media, Wiley, New York, 1997.
[3] For selected examples, see: a) E. Coutouli-Argyropoulou, P. Sarridis,
drophilic Groups in Aqueous Organic Reactions, The Chemical
Record, 2002, 2, 213; g) A. Meijer, S. Otto, J. B. F. N. Engberts, J.
Ben-Naim, Hydrophobic Interactions, Plenum Press, New York,
1980; m) C. Tanford, The Hydrophobic Effect, 2nd ed.; Wiley, New
(1S,5R)-5-(2-hydroxypropan-2-yl)-2-methylcyclohex-2-enol (trans-(À)-so-
brerol) 3:[41] white solid; m.p. 151–1538C; [a]2D0 =À150.1 (c=1.0, ethanol),
literature data:[42] [a]D20 =À150; 1H NMR (CDCl3, 600 MHz): d=5.56 (d,
J=4.8 Hz, 1H), 4.03 (m, 1H), 2.34 (brs, 2H), 2.11–2.09 (m, 1H), 2.04 (d,
J=12.6 Hz, 1H), 1.79 (s, 3H), 1.76–1.72 (m, 2H), 1.41–1.37 (m, 1H), 1.21
(s, 3H), 1.15 ppm (s, 3H); 13C NMR (CDCl3, 75 MHz): d=134.5, 125.2,
72.2, 68.6, 38.9, 32.6, 27.8, 27.3, 26.0, 20.8 ppm.
Hydrolysis of (À)-a-pinene oxide in H218O at 208C: A solution of (À)-a-
pinene oxide (15 mg, 0.1 mmol) in H218O (1 g, 97 atom% 18O) was added
to a 5 mL round-bottom flask equipped with a condenser. The reaction
mixture was stirred at 208C for 14 h. Then, the mixture was extracted
with EtOAc, washed with brine, dried over anhydrous Mg2SO4 and then
concentrated in vacuo. The residue was purified by silica gel chromatog-
raphy (50% EtOAc in P.E.) to give 8-18O-trans-(À)-sobrerol as the prod-
uct. The enantiomeric purity of trans-(À)-sobrerol was measured by GC
analysis.
Racemization of trans-(À)-sobrerol in mixed solvent of water and 1,4-di-
oxane at different concentrations of aq. HCl: A solution of trans-(À)-so-
brerol (51 mg, 0.3 mmol) in aq. HCl (30 mL, 100 mm) and 1,4-dioxane
(1.5 mL) was added to a 25 mL round-bottom flask at 208C. The reaction
mixture was stirred at 208C and was monitored by GC at 15, 30, 45, 60,
and 75 min intervals, respectively. The enantiomeric purity of trans-(À)-
sobrerol was measured by GC analysis.
Racemization of trans-(À)-sobrerol 3 in mixed solvent of water and 1,4-
dioxane heated at reflux (entry 6, Table 4) : A solution of trans-(À)-so-
brerol 3 (17 mg, 0.1 mmol) in distilled H2O (8 mL) and 1,4-dioxane
(4 mL) was added to a 25 mL round-bottom flask equipped with a con-
denser. The reaction mixture was heated to reflux and was monitored by
GC at 2, 6, 12, and 24 h, respectively. The enantiomeric purity of trans-
(À)-sobrerol and the ratio of trans-sobrerol to cis-sobrerol were mea-
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
column (30 mꢁ0.25 mmꢁ0.25 mm film thickness), flow rate 20 cmsecÀ1
,
T=1008C for 1 min, 5 degminÀ1 to 2208C, tR =21.0 min (trans-(À)-so-
brerol), 21.2 min (trans-(+)-sobrerol).
A
[4] For selected examples, see: a) K. J. Padiya, S. Gavade, B. Kardile,
M. Tiwari, S. Bajare, M. Mane, V. Gaware, S. Varghese, D. Harel, S.
8, 3259; f) G. K. van der Wel, J. W. Wijnen, J. B. F. N. Engberts, J.
,
T=1008C for 1 min, 5 degminÀ1 to 2208C, tR =21.9 min (cis-(+)-sobrer-
ol), 22.0 min (cis-(À)-sobrerol); 1H NMR (CDCl3, 400 MHz): d=5.48 (t,
J=1.4 Hz, 1H), 4.17 (brs, 1H), 2.24–2.19 (m, 1H), 2.08–2.02 (m, 2H),
1.92–1.84 (m, 1H), 1.75 (s, 3H), 1.70–1.62 (m, 2H), 1.38–1.28 (m, 1H),
1.21 (s, 3H), 1.19 ppm (s, 3H); 13C NMR (CDCl3, 100 MHz): d=136.4,
123.7, 72.3, 70.9, 43.9, 34.3, 27.4, 27.0, 26.4, 18.8 ppm.
[5] For selected examples, see: a) C. Santi, B. Battistelli, L. Testaferri,
Martꢄn-Zamora, R. Fernꢃndez, J. M. Lassaletta, Chem. Asian J.
2011, 6, 2287; c) X.-P. Fu, L. Liu, D. Wang, Y.-J. Chen, C.-J. Li,
2006, 45, 8103; j) S. Narayan, J. Muldoon, M. G. Finn, V. V. Fokin,
Racemization of chiral allylic alcohols in mixed solvent of water and 1,4-
dioxane heated at reflux: A solution of (S)-1-phenylethanol (0.1 mmol,
12 mg) in distilled H2O (10 mL) and 1,4-dioxane (2 mL) was added to a
25 mL round-bottom flask equipped with a condenser. The reaction mix-
ture was heated to reflux and was monitored by GC. The enantiomeric
purity of (S)-1-phenylethanol was reported by GC analysis.
Chem. Eur. J. 2013, 19, 314 – 323
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
321