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Streinz, Koutek, Saman:
EXPERIMENTAL
The starting aldehydes or ketones were either distilled or chromatographed on silica gel prior the use.
Commercially available triisopropylsilyl triflate (TIPSOTf) was used as a catalyst for all reactions
included in this paper and both TIPSOTf (24,846-0) and 2-mercaptoethanol (M370-1) were pur-
chased from Aldrich, Czech Republic and used without any purification. For IR (CCl4) and mass
recordings, Perkin–Elmer 580 spectrometer and ZAB EQ instrument (VG, Great Britain; EI 70 eV)
1
were used. Both H and 13C NMR spectra of compound 3e were taken in CDCl3 on a FT NMR spec-
trometer Varian UNITY-500 (499.8 MHz for 1H and 125.8 MHz for 13C, APT technique17, solvent
signal as an internal standard, δ 77.00). All other compounds were characterized using UNITY-200
1
spectrometer (200.04 MHz for H, in deuteriochloroform with tetramethylsilane as an internal standard).
The homo-correlated 2D NMR COSY spectrum18 was obtained using the standard pulse sequence
(designed by the producer) under following parameters: spectral width in both f1 and f2 dimensions
4 100 Hz, number of scans 4, 256 increments, recycle delay 1 s, acquisition time 0.25 s, 90° pulse
14 ms, data matrix for processing 2 048 × 2 048; processing function: sine-bell in both dimensions.
The resulting spectrum was symmetrized around the main diagonal. For uninterchangeable assign-
ment of signals in 13C NMR spectrum, the hetero-correlated 2D NMR spectrum was taken by HMQC
technique19 using the standard pulse sequence (given by the spectrometer producer; following set of
parameters used: spectral width in both f1 and f2 dimensions 4 000 and 25 000 Hz, respectively; num-
1
ber of scans 8, increments of f1 300, recycle delay 1 s, acquisition time 0.2 s, 90° pulse for H 29 ms,
data matrix for processing 2 048 × 2 048, no weighted function). NMR data for all compounds are
given in both ppm (chemical shifts) and Hz (coupling constants) units.
General Procedure for Preparation of 1,3-Oxathiolanes 3a–3k
To the stirred solution of TIPSOTf (3.1 mg, 0.01 mmol) in dioxane (0.5 ml), the mixture of aldehyde
or ketone (1 mmol) and 2-mercaptoethanol (0.105 ml, 1.5 mmol) in dioxane (0.5 ml) was quickly
added at room temperature. Then the reaction vessel was heated on 85 °C and stirring was continued
for additional 0.5 h at this temperature. After being cooled to the room temperature, the reaction
mixture was mixed up with triethylamine (4 µl, 0.03 mmol), diluted with saturated sodium hydrogen-
carbonate solution (2 ml), extracted with the pentane–ether mixture (1 : 1, 3 × 3 ml) and the com-
bined extracts dried over Na2SO4. Simple evaporation (rotatory evaporator), chromatography on
Florisil (10 times, pure pentane as a solvent) and the final evaporation at 1.6 kPa/r.t. for 45 min gave
pure products 3a–3i and 3k. Compound 3j, because of its low boiling point was obtained by remov-
ing pentane using 1.5 × 8 cm Vigreux column and the rest was redistilled by short-path distillation.
The analytical data and the survey of structures prepared are summarized in the Table I.
1,1-Bis(2-hydroxyethylthio)-2-methylpentane (2e)
To the solution of TIPSOTf (4.6 mg, 0.015 mmol) in dioxane (0.7 ml) under the stirring at room
temperature, the mixture of 2-methylpentanal (0.15 g, 1.5 mmol) and 2-mercaptoethanol (158 µl, 2.2 mmol)
in dioxane (1.5 ml) was quickly added. The reaction mixture was then decomposed with saturated
sodium hydrogencarbonate solution (2 ml), extracted with ether (3 × 3 ml) and the solution dried
with Na2SO4. After evaporation of solvents, the residue was chromatographed on silica gel with the
pentane–ether mixture (1 : 1). Evaporation of the solvent (rotatory evaporator), and final evaporation
at 1.6 kPa/r.t. for 45 min gave 0.196 g (55%) of 2e. 1H NMR spectrum, 0.92 t, 3 H, J = 6.4
(CH3CH2); 1.08 d, 3 H, J = 6.8 (CH3CH); 1.20–2.02 m, 4 H (CH2); 2.72–3.01 m, 4 H (SCH2); 3.74–3.85 m,
4 H (CH2O); 3.89 d, 1 H, J = 3.4 (CH(O)(S)). IR spectrum: 3 381, 1 465, 1 377, 1 055 cm–1. Mass
spectrum, m/z (%): 238 (M+, 6), 161 (37), 83 (100), 61 (15), 55 (34), 41 (28).
Collect. Czech. Chem. Commun. (Vol. 62) (1997)