K. Abbaspour Tehrani et al. / Tetrahedron 56 (2000) 6541±6548
6545
as a light yellow oil in 81% yield; bp 70±748C/15 Torr. 1H
NMR (270 MHz, CDCl3): d 0.99 (3H, t, J7.3 Hz,
SCH2CH3); 1.21 (3H, t, J7.4 Hz, CH3CH2); 1.68 (1H,
d£q, J7.3, 22.0 Hz, CH3C(H)H); 1.83 (1H, d£q, J7.4,
22.0 Hz, CH3C(H)H); 2.27 (3H, s, CH3CO); 2.35±2.51 (2H,
m, SCH2); 3.13 (1H, t, J7.6 Hz, CH). 13C NMR (68 MHz,
CDCl3): d 12.00 (SCH2CH3); 14.47 (CH3CH2); 23.38
(CH3CO); 24.24; 25.71; 55.78 (CH); 205.22 (CvO). IR
(NaCl, cm21): n1702 (CvO). MS (70 eV) m/z (%):
146(M1; 27); 105(5); 103(100); 86(6); 75(26); 73(3);
71(4); 61(19); 59 (3); 47(9); 45(6); 43(22); 41(25). Anal.
Calcd for C7H14OS: C 57.49%; H 9.65%. Found: C 57.63%;
H 9.76%.
134(85); 133(5); 115(2); 105(86); 89(100); 77(52); 61(22);
59(4); 55(4); 51(13); 45(2).
General procedure for the synthesis of a-chloro-a-
sulfenylated ketones 3a±d,f
To an ice cooled solution of a-sulfenylated ketones 2
(0.10 mol) in 100 mL of carbon tetrachloride was added
N-chlorosuccinimide (14.69 g, 0.11 mol). The resulting
suspension is stirred for 1 h, ®ltered and evaporated to
give pure a-chloro-a-sulfenylated sul®des in quantitative
yield. a-Chloro-a-sulfenylated ketones 3 were used as
such in the next step.
2-(Ethylthio)-3-pentanone 2c. Compound 2c was obtained
as a light yellow oil in 79% yield; bp 59±628C/12 Torr. Lit.
bp 72±738C/11 Torr.20a 1H NMR (60 MHz, CDCl3): d 1.03
(3H, t, J6.9 Hz, COCH2CH3); 1.17 (3H, t, J7.5 Hz,
CH3CH2S); 1.34 (3H, d, J6.9 Hz, CHCH3); 2.22±2.82
(4H, m, SCH2 and CH2CH3); 3.32 (1H, q, J6.9 Hz, CH).
IR (NaCl, cm21): n1705 (CvO).
3-Chloro-3-(ethylthio)-2-butanone 3a. Compound 3a was
obtained as a yellow oil in quantitative yield. H NMR
1
(270 MHz, C6D6): d 0.97 (3H, t, J7.6 Hz, SCH2CH3);
1.79 (3H, s, CH3CSEt); 2.17 (3H, s, CH3CO); 2.42 (2H,
,q, J7.6 Hz, SCH2CH3). 13C NMR (68 MHz, C6D6): d
13.46 (SCH2CH3); 23.63; 25.44 and 28.30 (CH3CO and
CH3CSCH2); 79.69 (CCl); 197.46 (CvO). IR (NaCl,
cm21): n1720 (CvO). The lability of this compound
did not allow the obtention of correct mass spectra1 data
or elementary analyses. Upon GC-MS analysis hydrogen
chloride was eliminated yielding the corresponding vinyl
sul®de.
3-(Ethylthio)-2-heptanone 2d. Compound 2d was obtained
as a yellow oil in 71% yield; bp 87±888C/12 Torr. 1H NMR
(270 MHz, CDCl3): d 0.90 (3H, t, J6.9 Hz, CH2CH3); 1.21
(3H, t, J7.4 Hz, CH3CH2S); 1.38±1.48 (4H, m); 1.52±1.70
(1H, m,); 1.72±1.88 (1H, m,), 2.26 (3H, s, CH3CO); 2.38±
2.51 (2H, m, SCH2); 3.19 (1H, t, J7.6 Hz, CH). 13C NMR
(68 MHz, CDCl3): d 13.71 (CH3); 14.29 (CH3); 22.28
(CH3CO); 24.24 (CH); 25.43; 29.44; 29.71 (CH2) 53.96
(CH); 205.43 (CvO). IR (NaCl, cm21): n1705 (CvO).
MS (70 eV) m/z (%): 174(M1; 26); 133(5); 131(97);
114(11); 89(9); 77(5); 75(100); 73(3); 71(7); 69(65);
67(3); 61(8); 60(5); 59(5); 55(6); 47(5); 43(30); 41(19).
3-Chloro-3-(ethylthio)-2-pentanone 3b. Compound 3b
was obtained as a yellow oil in quantitative yield. 1H
NMR (270 MHz, CDCl3): d 1.09 and 1.23 (2£3H, 2£t,
J7.3 Hz and 7.6 Hz, CH2CH3 and SCH2CH3); 2.1±2.3
(2H, m, CH2CH3); 2.41 (3H, s, CH3CO); 2.5±2.7 (2H, m,
SCH2CH3). 13C NMR (68 MHz, CDCl3): d 9.38 and 13.37
(CH2CH3 and SCH2CH3); 24.22 (CH3CO); 24.83 and 32.67
(CH2CH3 and SCH2CH3); 85.01 (CCl); 197.98 (CvO). IR
(NaCl, cm21): n1715 (CvO). The lability of this
compound did not allow the obtention of correct mass
spectral data or elementary analyses. Upon GC-MS analysis
hydrogen chloride was eliminated yielding the correspond-
ing vinyl sul®de.
2-(Ethylthio)-1-phenyl-1-propanone 2e. Compound 2e
was obtained as a yellow oil in 85% yield. This compound
has been synthesized before, however, no spectra have been
published.21 For the sake of completeness spectroscopic
1
data are reported here; bp 146±1508C/15 Torr. H NMR
(270 MHz, CDCl3): d 1.17 (3H, t, J7.4 Hz, SCH2CH3);
1.57 (3H, d, J6.9 Hz, CH3CH); 2.41 (1H, d£q, J12.1,
7.4 Hz, SC(H)HCH3); 2.56 (1H, d£q, J12.1, 7.4 Hz,
SC(H)HCH3); 4.34 (1H, q, J6.9 Hz, CH); 7.4±7.6 (3H,
m, vCHmeta,para); 7.99±8.02 (2H, m, vCHortho). 13C NMR
(68 MHz, CDCl3): d 14.32 (SCH2CH3); 16.44 (CH3CH);
22.80 (SCH2); 41.51 (CH3CH); 128.53 and 128.57
(2£HCv); 132.94 (vCHpara); 135.70 (Cquat); 196.17
(CvO). IR (NaCl, cm21): n1678 (CvO). MS (70 eV)
m/z (%): 194(M1; 7); 134(85); 133(5); 115(2); 105(86);
89(100); 77(52); 61(22); 59(4); 55(4); 51(13); 45(2).
2-Chloro-2-(ethylthio)-3-pentanone 3c. Compound 3c
was obtained as a yellow oil in quantitative yield. 1H
NMR (270 MHz, CDCl3): d 1.14 and 1.25 (each 3H, each
t, J7.26 and 7.56 Hz, CH2CH3 and SCH2CH3); 1.98 (3H, s,
CH3CCl); 2.6±2.7 and 2.7±3.0 (4H, each m, CH2CH3 and
SCH2CH3). 13C NMR (68 MHz, CDCl3): d 8.77 and 13.46
(CH2CH3 and SCH2CH3); 25.18, 28.21 and 28.93 (SCH2,
CH3CCl and COCH2); 78.85 (CCl); 200.70 (CvO).). IR
(NaCl, cm21): n1715 (CvO). MS (70 eV) m/z (%):
180/182(M1; 7); 145(15); 144(8); 123/125(13); 95/7(10);
87(100); 85(10); 83(9); 61(15); 60(90); 59(28); 57(100);
55(20); 45(15); 44(20).
1-Phenyl-2-(phenylthio)-1-propanone 2f. Compound 2f
was obtained as a yellow oil in 83% yield. The spectro-
metric data of compound 2f (bp 126±1358C/0.01 Torr) are
in accordance with the literature data.22 1H NMR (270 MHz,
CDCl3): d 1.53 (3H, d, J6.9 Hz, CH3); 4.62 (1H, q,
J6.9 Hz, CH); 7.2±7.6 (8H, m, SC6H5 and vCHmeta,para);
7.9±8.0 (2H, m, vCHortho). 13C NMR (68 MHz, CDCl3): d
17.00 (CH3); 46.13 (CH); 127.42 (Cq); 128.52; 128.59 and
128.88 (3£HCv); 129.02 (Cq); 132.99 (vCHpara); 134.48
(vCH); 135.65 (Cquat); 196.13 (CvO). IR (NaCl, cm21):
n1680 (CvO). MS (70 eV) m/z (%): 194(M1; 7);
3-Chloro-3-(ethylthio)-2-heptanone 3d. Compound 3d
was obtained as a yellow oil in quantitative yield. 1H
NMR (270 MHz, C6D6): d 0.79 and 0.96 (2£3H, 2£t,
J7.25 Hz and 7.59 Hz, (CH2)3CH3 and SCH2CH3); 1.1±
1.5 and 1.5±1.7 (4H, 2£m, CH2(CH2)2CH3); 2.0±2.2 (2H,
m, CClCH2), 2.17 (3H, s, CH3CO); 2.3±2.5 (2H, m,
SCH2CH3). 13C NMR (68 MHz, C6D6): d 13.42 and 13.91
(SCH2CH3 and (CH2)3CH3); 22.68; 24.22; 25.16; 27.48 and
39.62 (CH3CO, SCH2 and (CH2)3); 84.82 (CCl); 197.28