L. Marzorati et al. / Tetrahedron: Asymmetry 23 (2012) 748–753
753
H = 5.35%, and N = 3.54%. Found C = 79.00%; H = 5.31%, and
N = 3.45%; 1H NMR (d; CDCl3) 4.99 (s; 1H; H-C-SPh), 6.94-7.18
(m; 5H; Harom), 7.24–7.37 (m; 15H; Harom).
4.6 mm i.d. ꢁ 25 cm length; 0.3 mL minꢀ1 using hexane/EtOH 9:1
as eluent).
Acknowledgement
4.1.5. 2-Phenylsulfanyl-N,N-diethylphenylacetamide 2a
Compound 2a was obtained in 63% yield by the same procedure
described above, after crystallization of the crude product. Mp 93-
94 °C from cyclohexane; Elemental analysis calculated for
We acknowledge FAPESP and CNPq for financial support.
References
C
18H21NOS, C = 72.20%; H = 7.07%, and N = 4.68%. Found
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4.1.7. Enantioenriched (S)-2b
(S)-(+)-Mandelic acid was treated with thionyl chloride in THF/
DMF24a to yield enantioenriched (R)-(ꢀ)-2-chlorophenylacetic acid;
½
a 2D5
ꢂ
¼ ꢀ99 (c 4.0, acetone); Lit.24b
½
a 2D5
ꢂ
¼ ꢀ191 (c 3.35, benzene).
This compound was exposed to K2CO3 and benzenethiol, in dioxane,
furnishing the enantioenriched (S)-(+)-2-phenylsulfanylphenylace-
tic acid {½a 2D5
ꢂ
¼ þ99 (c 4, acetone); Lit.25
½
a 2D5
ꢂ
¼ þ200 (1:1 CHCl3/
EtOH) with 93% ee for the (S)-(+) isomer. The assigned (S)-configura-
tion for the prepared compound was also confirmed via reduction of
the acid with lithium aluminum hydride in ether, to yield
enantioenriched (S)-(+)-2-phenylsulfanyl-2-phenylethanol. Lit.26
½
a 2D5
ꢂ
¼ þ206 (c 1.12, EtOH) for the (S)-isomer. Enantioenriched (S)-
(+)-2-phenylsulfanylphenylacetic acid (6.1 mmol) was treated with
thionyl chloride (12 mmol) at room temperature for 12 h. The crude
(S)-acid chloride, upon reaction with N,N-diphenylamine (12 mmol)
dissolved in CCl4 (10 mL), afforded enantioenriched (S)-2b
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71, 3479–3480.
(2.5 mmol; 41%; ½a D25
¼ þ12 (c 3.9, acetone) after dry flash chroma-
ꢂ
tography using hexane:ethyl acetate (20:1) as eluent). An ee of
approximately 30% was determined by HPLC (Sumichiral OA-2000