480 Letters in Organic Chemistry, 2009, Vol. 6, No. 6
Hassannia et al.
solvent peaks. The CI/MS spectra were recorded on a Varian
4000 GC/MS, using methanol as the ionization gas.
Lactones 10 and 11 were separated by chromatography
on silica gel using Et2O as eluent. 4-Tosyl-1,4-oxazepan-2-
one (10): Isolated as an oil. H-NMR (CDCl3, 500 MHz) ꢀ:
1
Compound 5 was graciously provided by Dr. J. M.
Bobbitt (University of Connecticut). Compound 6, 3-[(2-
hydroxyethyl)thio]-propan-1-ol was prepared according to
M. H. Goodrow et al. procedure [15a]. Compound 9 was
commercially available from Aldrich (rare chemicals
library).
7.63 (m, 2H), 7.34 (m, 2H), 4.35 (m, 2H), 3.46 (m, 2H), 3.32
(m, 2H), 2.92 (m, 2H), 2.44 (s, 3H) ppm; 13C-NMR (CDCl3,
125 MHz) ꢀ: 173.1, 144.6, 133.7, 130.3, 127.6, 68.2, 49.8,
43.4, 36.5, 21.8 ppm; MS: (CI) m/z (rel. intensity) 270
[M-H]+ (100), 228 (47). 4-Tosyl-1,4-oxazepan-7-one (11):
º
1
Isolated as a solid, mp. 154-156 C (dec). H-NMR (CDCl3,
500 MHz) ꢀ: 7.63 (m, 2H), 7.26 (m, 2H), 4.22, (m, 2H), 4.09
(s, 2H), 3.48 (m, 2H), 2.40 (s, 3H), 1.91 (m, 2H) ppm; 13C-
NMR (CDCl3, 125 MHz) ꢀ: 169.5, 144.5, 135.7, 130.3,
127.5, 68.1, 51.1, 49.1, 29.6, 21.8 ppm; MS: (CI) m/z (rel.
intensity) 270 [M-H]+ (0.3), 242 (100), 198 (17).
Synthesis of Diol 3
Tosylation of commercial 2-benzyloxyethanol, followed
by its reaction with 1,3-propanediol under basic conditions
(KOH, reflux in xylenes), afforded 3-[2-(benzyloxy)ethoxy]-
1-propanol [18]. The resulting benzyl ether was carefully
chromatographed on silica gel using EtOAc/Hexanes : 2/1 as
eluent (Rf = 0.35), to afford a high grade material, which
was directly debenzylated using H2/Pd/C (1atm) in an
EtOH/EtOAc 1:1 solution, in quantitative yield. The
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1
resulting diol 3 did not require any further purification. H-
NMR (CDCl3, 500 MHz) ꢀ = 3.75 (t, J = 5.5 Hz, 2H), 3.71
(m, 2H), 3.65 (t, J = 5.5 Hz, 2H), 3.55 (m, 2H), 3.05 (broad
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General Oxidation Procedure [9d]
To a mixture of the diol (1.0 mmol) and 4-acetylamino-
2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoro-
borate (5) (4.4 mmol) in CH2Cl2 (20 mL), 2,4,6-collidine
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1,4-Dioxepan-2-one (1) [1]: 1H-NMR (CDCl3, 500 MHz)
ꢀ: 4.41 (m, 2H), 4.34 (s, 2H), 3.91 (m, 2H), 2.12 (quintet, J =
5.5 Hz, 2H) ppm; 13C-NMR (CDCl3, 125 MHz) ꢀ: 172.8,
72.3, 71.3, 68.1, 31.2 ppm; MS: (CI) m/z 117 [M+H]+. 1,5-
Dioxepan-2-one (2) [1]: 1H-NMR (CDCl3, 500 MHz) ꢀ: 4.33
(m, 2H), 3.93 (m, 2H), 3.86 (m, 2H), 2.93 (m, 2H) ppm. 13C-
NMR (CDCl3, 125 MHz) ꢀ: 174.3, 71.0, 70.6, 65.0, 39.6
ppm; MS: (CI) m/z 117 [M+H]+.
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