3-Pyridinesulfonyl Azide: A Useful Reagent
UPDATES
moval of unchanged Bu6Sn2 and other apolar tin derivatives.
Elution with hexane/Et2O or hexane/EtOAc gave a crude
product that was purified by FC (hexane/Et2O or hexane/
EtOAc).
1104 cmÀ1. MS(EI, 70 eV): m/z (%)¼185 (MHþ, 5), 184
(Mþ, 35), 142 (80), 78 (93), 65 (48), 51 (100), 38 (78); anal. calcd.
for C5H4N4O2S(184.18): C 32.61, H 2.19, N 30.42; found: C
32.46, H 2.30, N 30.49.
General Procedure for Method B
DTBHN (15 mg, 0.09 mmol) was added to a mixture of radical
precursor (1.0 mmol), olefin (2.0 mmol), azidating agent
(3.0 mmol) and Bu6Sn2 (0.76 mL, 1.5 mmol) in dry C6H6
(2.0 mL) under N2. The reaction mixture was heated under re-
flux for 90 min. The solvent was removed under reduced pres-
sure and the crude product was filtered through silica gel. Elu-
tion with hexane allowed the removal of unchanged Bu6Sn2
and other apolar tin derivatives. Elution with hexane/Et2O or
hexane/EtOAc gave a crude product that was purified by FC
(hexane/Et2O or hexane/EtOAc).
Ethyl 4-Azidodecanoate (1)
(a) Prepared according to General Procedure A from ethyl 2-
iodoacetate (214 mg, 1.0 mmol), 1-octene (0.31 mL,
2.0 mmol), 3-PySO2N3 (553 mg, 3.0 mmol), Bu6Sn2 (0.76 mL,
1.5 mmol) and DTBHN (16 mg, 0.09 mmol). Filtration (hex-
ane then hexane/EtOAc, 90:10) and FC (hexane/EtOAc,
95:5) gave 1 as a colorless oil; yield: 194 mg (80%). Physical
and spectral data were in accordance to literature data.[4]
1H NMR (360 MHz, CDCl3): d¼4.15 (q, J¼7.3 Hz, 2H),
3.35 3.27 (m, 1H), 2.50 2.31 (m, 2H), 1.95 1.81 (m, 1H),
1.80 1.64 (m, 1H), 1.62 1.21 (m, 10H), 1.26 (t, J¼7.3 Hz,
3H), 0.89 (t, J¼6.8 Hz, 3H); 13C NMR (90 MHz, CDCl3): d¼
173.0, 62.2, 60.5, 34.4, 31.6, 30.9, 29.5, 29.0, 26.0, 22.5, 14.2, 14.0.
(b) Prepared according to General Procedure B from ethyl
2-iodoacetate (214 mg, 1.0 mmol), 1-octene (0.31 mL,
2.0 mmol), 3-PySO2N3 (553 mg, 3.0 mmol), Bu6Sn2 (0.76 mL,
1.5 mmol) and DTBHN (16 mg, 0.09 mmol). Filtration (hex-
ane then hexane/EtOAc, 90:10) and FC (hexane/EtOAc,
95:5) gave 1; yield: 197 mg (82%).
General Procedure for Method C
A 2 M solution of Et3B in dry EtOH was added at room tem-
perature over 1 h by using a syringe pump to an open-air, vig-
orously stirred mixture of radical precursor, olefin and azidat-
ing agent (3.0 mmol) in solvent (2.0 mL) (important: the nee-
dle should be immersed into the reaction mixture in order to
avoid a direct contact of Et3B drops with air). The reaction
was stirred for 15 min more and hexane (5 mL) was added. Af-
ter separation, the aqueous layer was extracted with Et2O and
the combined organic phases were washed with brine and dried
over Na2SO4. The crude product was purified by FC (hexane/
EtOAc).
(c) Prepared according to General Procedure C from ethyl
2-iodoacetate (214 mg, 1.0 mmol), 1-octene (0.31 mL,
2.0 mmol), 3-PySO2N3 (553 mg, 3.0 mmol) and Et3B
(1.50 mL, 3.0 mmol) in water (2.0 mL). FC (hexane/EtOAc,
95:5) gave 1; yield: 196 mg (81%).
(d) Prepared according to General Procedure C from 1-oc-
tene (112 mg, 1.0 mmol), ethyl 2-iodoacetate (257 mg,
1.2 mmol), 3-PySO2N3 (553 mg, 3.0 mmol) and Et3B
(1.75 mL, 3.5 mmol) in water (2.0 mL). FC (hexane/EtOAc,
95:5) gave 1; yield: 167 mg (69%).
3-Pyridinesulfonyl Azide
A mixture of 3-pyridinesulfonic acid (10.40 g, 65.0 mmol),
phosphorus pentachloride (16.25 g, 78.0 mmol) and phospho-
rus oxychloride (20.0 mL) was stirred overnight at 1208C un-
der N2. The reaction mixture was cooled to room temperature
and diluted with dry CH2Cl2 (30 mL). The reaction mixture was
further cooled to 58C and saturated with HCl gas. The white
precipitate was collected by filtration, washed with dry
CH2Cl2 and dried under reduced pressure. The 3-pyridinesul-
fonyl chloride hydrochloride was obtained as a white powder
and used immediately; yield: 13.5 g (97%).[9]
Ethyl 4-Azido-8-bromooctanoate (2)
(a) Prepared according to General Procedure A from ethyl 2-
iodoacetate (214 mg, 1.0 mmol), 6-bromo-1-hexene (0.27 mL,
2.0 mmol), 3-PySO2N3 (553 mg, 3.0 mmol), Bu6Sn2 (0.76 mL,
1.5 mmol) and DTBHN (16 mg, 0.09 mmol). Filtration (hex-
ane then hexane/EtOAc, 90:10) and FC (hexane/EtOAc,
95:5) gave 2 as a colorless liquid; yield: 218 mg (75%). Physical
and spectral data were in accordance to literature data.[4]
1H NMR (300 MHz, CDCl3): d¼4.15 (q, J¼7.3 Hz, 2H), 3.42
(t, J¼6.8 Hz, 2H), 3.38 3.29 (m, 1H), 2.52 2.36 (m, 2H),
1.96 1.83 (m, 3H), 1.81 1.69 (m, 1H), 1.66 1.49 (m, 4H),
1.27 (t, J¼7.3 Hz, 3H); 13C NMR (75 MHz, CDCl3): d¼
172.6, 61.8, 60.4, 33.4, 33.1, 32.2, 30.6, 29.3, 24.5, 14.1.
(b) Prepared according to General Procedure B from ethyl
2-iodoacetate (214 mg, 1.0 mmol), 6-bromo-1-hexene
(0.27 mL, 2.0 mmol), 3-PySO2N3 (553 mg, 3.0 mmol), Bu6Sn2
(0.76 mL, 1.5 mmol) and DTBHN (16 mg, 0.09 mmol). Filtra-
tion (hexane then hexane/EtOAc, 90:10) and FC (hexane/
EtOAc, 95:5) gave 2; yield: 234 mg (80%).
A solution of sodium azide (14.3 g, 220 mmol) in water
(40 mL) was added dropwise at 08C to a solution of 3-pyridine-
sulfonyl chloride hydrochloride (22.5 g, 105 mmol) in acetone
(100 mL) and water (20 mL). The mixture was stirred over-
night at room temperature. Acetone was removed under re-
duced pressure and the resulting aqueous phase was extracted
with EtOAc (200 mL), washed with water (2ꢀ100 mL), 5%
Na2CO3 (2ꢀ100 mL), water (2ꢀ100 mL), dried over MgSO4
and concentrated under vacuum. The residue was purified by
precipitation in hexane/Et2O (10:1) at À788C to give 3-
1
PySO2N3 as a colorless liquid; yield: 15.40 g (80%). H NMR
(300 MHz, CDCl3): d¼9.18 (d, J¼2.6 Hz, 1H), 8.95 (dd, J¼
4.8, 1.5 Hz, 1H), 8.24 (ddd, J¼8.1, 2.6, 1.5 Hz, 1H), 7.58 (ddd,
J¼8.1, 4.8, 0.7 Hz, 1H); 13C NMR (75 MHz, CDCl3): d¼
154.9, 147.8, 135.1, 134.9, 124.0; IR (film): n¼3064, 2358,
2340, 2136, 1575, 1469, 1419, 1375, 1328, 1175, 1124,
Adv. Synth. Catal. 2004, 346, 925 928
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¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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