D.B.G. Williams, T.E. Netshiozwi / Tetrahedron 65 (2009) 9973–9982
9977
a bulb-to-bulb distillation set-up at 175 ꢁC/80 millitorr to give an oily
substance 0.72 g (48%).
(dd, 4H, JHH¼12.0 Hz, JHP¼6.6 Hz), 7.80–7.60 (m, 6H), 4.25 (dt, 2H,
JHP¼13.4 Hz, JHH¼6.7 Hz), 2.00 (septet, 1H, JHH¼6.7 Hz), 1.82 (q, 2H,
JHH¼6.7 Hz), 1.10 (d, 6H, JHH¼6.6 Hz); 13C NMR (CDCl3, 75.5 MHz):
1H NMR (CDCl3, 300 MHz):
d
7.58–7.50 (m, 4H), 7.39–7.26 (m,
6H), 1.76 (q, 2H, JHH¼7.4 Hz), 1.39 (s, 6H), 0.95 (t, 3H, JHH¼7.4 Hz);
13C NMR (CDCl3, 75.5 MHz):
d
132.0 (d, JCP¼2.6 Hz), 131.5 (d, JCP¼10.0 Hz), 131.5 (d,
d
143.8 (d, JCP¼16.0 Hz), 130.1 (d,
JCP¼136.3 Hz), 128.4 (d, JCP¼13.1 Hz), 63.3 (d, JCP¼6.0 Hz), 39.2 (d,
JCP¼20.1 Hz), 129.8 (d, JCP¼18.5 Hz), 128.6 (s), 128.1 (d, JCP¼6.9 Hz),
79.1 (d, JCP¼11.5 Hz), 35.6 (d, JCP¼6.0 Hz), 27.5 (d, JCP¼9.5 Hz), 27.3
(d, JCP¼9.5 Hz), 8.8 (d, JCP¼14.0 Hz); 31P NMR (CDCl3, 121.5 MHz):
JCP¼6.5 Hz), 24.6 (s), 22.3 (s); 31P NMR (CDCl3, 121.5 MHz):
d 30.1;
EIMS m/z 288 ([M]þ, 0.2%), 245 ([C14H14O2P]þ, 17%), 219
([C12H12O2P]þ, 100%), 201 ([C12H10OP]þ, 25%); CI-HRMS C17H21O2P
calcd 288.1279 found 288.1284; IR (vmax cmꢀ1): 2960 (s, C–H), 1439
(s, P-phenyl), 1223 (s, P]O), 1129 (s, P–O–C).
d
78.3; EIMS m/z 243 ([C15H16OP]þ, 21%), 203 ([C12H13OP]þ, 100%);
CI-HRMS C17H21OP calcd 272.1330 found 272.1344; IR (vmax cmꢀ1):
2971 (s, C–H), 1434 (s, P-phenyl), 939 (s, P–O–C).
3.3.5. 1,1-Dimethyl-1-ethyl diphenylphosphinate (3e). Scale: 0.60 g
3.3. General procedure for the preparation of alkyl
diphenylphosphinates (3)
(2.3 mmol); yield: 0.51 g (80%); mp 107–109 ꢁC; 1H NMR (CDCl3,
300 MHz):
d
7.87 (dd, 4H, JHH¼12.5 Hz, JHP¼1.7 Hz), 7.48–7.32 (m,
6H), 1.59 (s, 9H); 13C NMR (CDCl3, 75.5 MHz):
d
134.6 (d,
A solution of 30% hydrogen peroxide (3.0 mL) was added to the
relevant alkyl diphenylphosphinite in benzene (10.0 mL) and
the resulting reaction mixture was stirred at rt for 1 h. Upon the
completion of the reaction (31P NMR monitored), water (10.0 mL)
was added, followed by extraction with chloroform (3ꢂ10.0 mL).
The combined organic phase was dried over anhydrous MgSO4 and
the solvent was removed on a rotary evaporator. The crude mixture
was purified by column chromatography (silica gel, ethyl acetate/
hexane 2:3) to give the product of as crystalline material.
JCP¼138.6 Hz), 131.4 (JCP¼2.9 Hz), 131.3 (d, JCP¼10.3 Hz), 128.2 (d,
JCP¼13.2 Hz), 83.6 (d, JCP¼8.3 Hz), 30.9 (d, JCP¼3.7 Hz); 31P NMR
(CDCl3, 121.5 MHz):
d
19.4; EIMS m/z 259 ([M-CH3]þ, 1%), 219
([C12H12O2P]þ, 100%), 201 ([C12H10OP]þ, 29%); CI-HRMS C16H19O2P
calcd 274.1123 found 274.1123; IR (vmax cmꢀ1): 2989 (s, C–H),1438 (s,
P-phenyl), 1224 (s, P]O), 1109 (s, P–O–C).
3.3.6. 1,1-Dimethyl-1-propyl diphenylphosphinate (3f). Scale: 0.50 g
(1.8 mmol); yield: 0.43 g (81%); mp 65–66 ꢁC; 1H NMR (CDCl3,
300 MHz):
d
7.76 (dd, 4H, JHH¼12.4 Hz, JHP¼1.6 Hz), 7.45–7.33 (m, 6H),
3.3.1. 2,2-Dimethyl-1-propyl
diphenylphosphinate
(3a). Scale:
1.76 (q, 2H, JHH¼7.4 Hz),1.42 (s, 6H), 0.94 (t, 3H, JHH¼7.4 Hz); 13C NMR
0.30 g (1 mmol), yield: 0.21 g (66%); mp 78–79 ꢁC; 1H NMR (CDCl3,
(CDCl3, 75.5 MHz):
d
134.6 (d, JCP¼139.1 Hz), 131.4 (s), 131.2 (d,
300 MHz):
d
7.89 (dd, 4H, JHH¼12.4 Hz, JHP¼1.6 Hz), 7.52–7.38 (m,
JCP¼10.0 Hz), 128.2 (d, JCP¼13.2 Hz), 86.5 (d, JCP¼9.2 Hz), 36.5 (d,
6H), 3.63 (d, 2H, JHP¼4.9 Hz), 1.05 (s, 9H); 13C NMR (CDCl3,
JCP¼5.2 Hz), 28.0 (d, JCP¼30.6 Hz, 2C), 8.70 (d, JCP¼14.0 Hz); 31P NMR
75.5 MHz):
d
132.0 (d, JCP¼2.6 Hz), 131.6 (d, JCP¼136.4 Hz), 131.6 (d,
(CDCl3, 121.5 MHz): d
19.3; EIMS m/z 273 ([M-CH3]þ, 5%), 259
JCP¼10.0 Hz), 128.5 (d, JCP¼13.1 Hz), 73.8 (d, JCP¼6.6 Hz), 32.2 (d,
([C15H16O2P]þ, 19%), 219 ([C12H12O2P]þ, 100%), 201 ([C12H11OP]þ,
82%); CI-HRMS C17H21O2P calcd 288.1279 found 288.1283; IR (vmax
cmꢀ1): 2978 (s, C–H), 1437 (s, P-phenyl), 1228 (s, P]O), 1124
(s, P–O–C).
JCP¼7.4 Hz), 26.2 (s); 31P NMR (CDCl3, 121.5 MHz):
d 24.3; EIMS m/z
288 ([M]þ, 1%), 273 ([C16H18O2P]þ, 7%), 231 ([C13H12O2P]þ, 6%), 219
([C12H12O2P]þ, 100%), 201 ([C12H10OP]þ, 34%); CI-HRMS C17H21O2P
calcd 288.1279 found 288.1273; IR (vmax cmꢀ1): 2924 (s, C–H), 1439
(s, P-phenyl), 1222 (s, P]O), 1019 (s, P–O–C).
3.4. General procedure for the preparation of alkyl
diphenylphosphinothioates (4)
3.3.2. 1,2-Dimethyl-1-propyl diphenylphosphinate (3b). Scale: 0.40 g
(1.5 mmol), yield: 0.27 g (84%); mp 79–82 ꢁC; 1H NMR (CDCl3,
A mixture of alkyl diphenylphosphinite and 1.1 equiv of ele-
mental sulfur dissolved in toluene was heated at reflux for 2 h. The
progress of the conversion was monitored by 31P NMR analysis.
Upon completion of the reaction, the reaction mixture was cooled
to room temperature. The excess sulfur was filtered off and the
filtrate was concentrated on a rotary evaporator to give a solid
crude product, which was further purified by column chromatog-
raphy (silica gel, ethyl acetate/hexane 1:4).
300 MHz):
d 7.95–7.72 (m, 4H), 7.69–7.40 (m, 6H), 4.43–4.32 (m,
1H), 2.00 (dq, 1H, JHH¼6.9 Hz, JHP¼1.8 Hz), 1.30 (d, 3H, JHH¼6.6 Hz),
1.01 (d, 3H, JHH¼6.9 Hz), 0.98 (d, 3H, JHH¼6.7 Hz); 13C NMR (CDCl3,
75.5 MHz):
d
132.4 (d, JCP¼122.2 Hz), 132.4 (d, JCP¼2.6 Hz), 132.1 (d,
JCP¼123.9 Hz), 131.7 (s), 131.4 (d, JCP¼8.6 Hz), 131.3 (d, JCP¼9.7 Hz),
128.7 (d, JCP¼12.8 Hz), 128.1 (d, JCP¼13.4 Hz), 77.6 (d, JCP¼6.6 Hz),
33.7 (d, JCP¼5.2 Hz), 17.9 (s), 17.7 (s), 17.2 (s); 31P NMR (CDCl3,
121.5 MHz):
d
23.1; EIMS m/z 288 ([M]þ, 0.5%), 245 ([C14H14O2P]þ,
10%), 219 ([C12H12O2P]þ, 100%), 201 ([C12H10OP]þ, 79%); CI-HRMS
C17H21O2P calcd 288.1279 found 288.1291; IR (vmax cmꢀ1): 2966 (s,
C–H), 1438 (s, P-phenyl), 1228 (s, P]O), 1129 (s, P–O–C).
3.4.1. 2,2-Dimethyl-1-propyl diphenylphosphinothioate (4a). Scale:
0.30 g (1.1 mmol); yield: 0.26 g (78%); mp 88–90 ꢁC; 1H NMR
(CDCl3, 300 MHz):
d
7.90 (dd, 4H, JHH¼12.8 Hz), 7.54–7.34 (m, 6H),
3.53 (d, 2H, JHP¼5.8 Hz), 0.87 (s, 9H); 13C NMR (CDCl3, 75.5 MHz):
3.3.3. 1,2,2-Trimethyl-1-propyl diphenylphosphinate(3c). Scale: 0.35 g
d
134.4 (d, JCP¼110.5 Hz), 131.5 (d, JCP¼2.9 Hz), 130.9 (d,
(1.2 mmol); yield: 0.25 g (68%); mp 63–64 ꢁC; 1H NMR (CDCl3,
JCP¼11.5 Hz), 128.2 (d, JCP¼13.5 Hz), 73.6 (d, JCP¼6.6 Hz), 31.9 (d,
300 MHz):
d
7.96–7.74 (m, 4H), 7.70–7.45 (m, 6H), 4.37 (dq, 1H,
JCP¼8.5 Hz), 26.3 (s); 31P NMR (CDCl3, 121.1 MHz):
d 74.1; EIMS m/z
JHP¼8.0 Hz, JHH¼6.3 Hz), 1.28 (d, 3H, JHH¼6.3 Hz), 1.00 (s, 9H); 13C
304 ([M]þ 40%), 235 ([C12H12OPS]þ, 36%), 218 ([C12H11PS]þ, 100%),
201 ([C12H10OP]þ, 21%); CI-HRMS C17H21OPS calcd 304.1051 found
304.1046; IR (vmax cmꢀ1): 2952 (s, C–H), 1436 (s, P-phenyl), 1111 (s,
P–O–C), 730 (s, P]S).
NMR (CDCl3, 75.5 MHz):
d
131.8 (d, JCP¼2.6 Hz),131.8 (d, JCP¼2.9 Hz),
131.6 (d, JCP¼10.2 Hz),131.5 (d, JCP¼10.3 Hz),129.9 (d, JCP¼134.4 Hz),
129.7 (d, JCP¼135.8 Hz), 128.3 (d, JCP¼13.1 Hz), 80.8 (d, JCP¼7.2 Hz),
35.2 (d, JCP¼6.0 Hz), 25.8 (s), 17.1 (s); 31P NMR (CDCl3, 121.5 MHz):
d
22.7; EIMS m/z 302 ([M]þ, 1%), 245 ([C14H14O2P]þ, 26%), 219
3.4.2. 1,2-Dimethyl-1-propyl diphenylphosphinothioate (4b). Scale:
([C12H12O2P]þ, 100%), 201 ([C12H10OP]þ, 93%); CI-HRMS C18H23OP
calcd 302.1436 found 302.1423; IR (vmax cmꢀ1): 2963 (s, C–H), 1438
(s, P-phenyl), 1223 (s, P]O), 958 (s, P–O–C).
0.60 g (2.0 mmol); yield: 0.52 g (76%); mp 68–70 ꢁC; 1H NMR
(CDCl3, 300 MHz):
d 8.15–7.74 (m, 4H), 7.54–7.38 (m, 6H), 4.68 (dq,
1H, JHH¼6.3 Hz, JHP¼4.7 Hz), 1.88 (dq, 1H, JHH¼6.9 Hz), 1.12 (d, 3H,
JHH¼6.3 Hz), 0.91 (d, 3H, JHH¼6.9 Hz), 0.88 (d, 3H, JHH¼6.8 Hz); 13
C
3.3.4. 3-Methyl-1-butyl diphenylphosphinate (3d). Scale: 0.60 g,
NMR (CDCl3, 75.5 MHz):
d
135.9 (d, JCP¼109.1 Hz), 135.8 (d,
yield: 0.54 g (86%); mp 55–57 ꢁC; 1H NMR (CDCl3, 300 MHz):
d
8.02
JCP¼113.7 Hz), 131.5 (d, JCP¼2.9 Hz), 131.4 (d, JCP¼3.1 Hz), 131.2 (d,