E
H. K. Moon et al.
Letter
Synlett
The reaction method described in this work permits ef-
ficient, convenient, and ecofriendly preparation of symmet-
ric and asymmetric carbonates. This method takes advan-
tage of alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6H)-
carboxylates, which are readily synthesized and derived
from quantitatively isolable and recyclable 4,5-dichloropyr-
idazin-3(2H)-one.4a,d,e,7 We believe that the method report-
ed here8 will find a broad range of applications for alkoxy-
and aryloxycarbonyl sources in flow and ecofriendly syn-
thetic chemistry.
Org. Chem. 2004, 8, 1463. (f) Kim, J.-J.; Park, Y.-D.; Cho, S.-D.;
Kim, H.-K.; Kang, Y.-J.; Lee, S.-G.; Falck, J. R.; Shiro, M.; Yoon, Y.-J.
Bull. Korean Chem. Soc. 2004, 25, 1273.
(5) (a) Shieh, W.-C.; Dell, S.; Repič, O. J. Org. Chem. 2002, 67, 2188.
(b) Douglas, J. E.; Campbell, G.; Wigfield, D. C. Can. J. Chem. 1993,
71, 1841.
(7) Ryu, K. E.; Kim, B. R.; Sung, G. H.; Yoon, H. J.; Yoon, Y.-J. Synlett
2015, 26, 1985.
(8) Symmetric Carbonates 2a–e; General Procedure Using Potas-
sium Carbonate
K2CO3 (1.0 mmol) was added to a solution of the appropriate
pyridazine 1 (1.0 mmol) in THF (20 mL), and the mixture was
allowed to reflux until pyridazine 1 was consumed (TLC). The
solvent was evaporated under reduced pressure, and the sym-
metric carbonates 2a–e were isolated by column chromatogra-
phy [silica gel (2.5 × 3 cm), CH2Cl2]. Once the desired product
had been isolated, the column was eluted with EtOAc to isolate
4,5-dichloropyridazin-3(2H)-one, which was obtained quanti-
tatively and reused.
Acknowledgment
This research was supported by the Basic Science Research Program
through the NRF of Korea funded by the Ministry of Science, ICT, &
Future Planning (NRF-2014R1A1A1002938) and the Ministry of Edu-
cation (NRF20100020209).
Diphenyl Carbonate (2)
White solid; yield: 193 mg (80%); mp 75–76 °C. IR (KBr): 3058,
1773, 1592, 1490, 1255, 1233, 1182, 1071, 1016, 996, 751, 685,
501 cm–1. 1H NMR (300 MHz, DMSO-d6): δ = 7.30–7.35 (m, 2 H),
7.40–7.51 (m, 8 H). 13C NMR (75 MHz, DMSO-d6): δ = 121.2,
126.4, 129.7, 150.7, 151.7. HRMS (EI): m/z [M+] calcd for
Supporting Information
Supporting information for this article is available online at
S
u
p
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ortioInfgrmoaitn
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13H10O3: 214.0630; found: 214.0634.
References and Notes
Symmetric (2) or Asymmetric (4 and 6) Carbonates; General
Procedure Using Potassium tert-Butoxide
(1) These authors contributed equally to this work.
Alcohol 3 or 5 (0.84 mmol) was added to a solution of the
appropriate pyridazine 1 (0.7 mmol) and t-BuOK (0.84 mmol) in
toluene (10 mL), and the mixture was stirred at r.t. until pyri-
dazine 1 was consumed (TLC). 10% aq NaOH (50 mL) and CH2Cl2
(30 mL) were added to the mixture with stirring. The organic
layer was separated, washed with H2O (50 mL), dried (MgSO4),
and concentrated under reduced pressure. The residue was
transferred to an open-bed column of silica gel (2.5 × 4 cm),
which was eluted with hexane–EtOAc (3:1) to give the symmet-
ric carbonates 2, or the asymmetric carbonates 4 or 6, and then
eluted with EtOAc to isolate 4,5-dichloropyridazin-3(2H)-one
quantitatively for reuse.
(2) (a) Gymer, G. E.; Narayanaswami, S. In Comprehensive Organic
Functional Group Transformations; Vol. 6, Part 4; Katritzky, A.
R.; Meth-Cohn, O.; Rees, C. W., Eds.; Chap. 6.14; Pergamon:
Oxford, 1995, 407. (b) Hua, R.; Shimada, S.; Tanaka, M. J. Am.
Chem. Soc. 1998, 120, 12365.
(3) (a) Kreutzberger, C. B. In Kirk-Othmer Encyclopedia of Chemical
Technology; Wiley: New York, 2001,
;
DOI: 10.1002/
0471238961.0301180204011312.a01.pub2. (b) Sammet, B.
Synlett 2009, 3050. (c) Cotarca, L.; Eckert, H. Phosgenations: A
Handbook; Wiley-VCH: Weinheim, 2003.
(4) (a) Lee, H.-G.; Kim, M.-J.; Park, S.-E.; Kim, J.-J.; Lee, S.-G.; Yoon,
Y.-J. Synlett 2009, 2809. (b) Kim, S.-K.; Kweon, D.-H.; Cho, S.-D.;
Kang, Y.-J.; Park, K.-H.; Lee, S.-G.; Yoon, Y.-J. J. Heterocycl. Chem.
2005, 42, 353. (c) Kim, J. J.; Park, Y. D.; Kim, H. K.; Cho, S. D.;
Kim, J. K.; Lee, S. G.; Yoon, Y. J. Synth. Commun. 2006, 35, 731.
(d) Kim, B. R.; Sung, G. H.; Ryu, K. E.; Yoon, H. J.; Lee, S.-G.; Yoon,
Y.-J. Synlett 2014, 25, 1909. (e) Lee, S.-G.; Kim, J.-J.; Kim, H.-K.;
Kweon, D.-H.; Kang, Y.-J.; Cho, S.-D.; Kim, S.-K.; Yoon, Y.-J. Curr.
Phenyl 2-Phenylethyl Carbonate (4)
White solid; yield: 148 mg (87%); mp 83–85 °C. IR (KBr): 3109,
3081, 3058, 3033, 2969, 2938, 2895, 2868, 1753, 1492, 1260,
.
1210, 1077, 967, 778, 753, 699, 499 cm–1 1H NMR (300 MHz,
CDCl3): δ = 3.00 (t, J = 7.0 Hz, 2 H), 4.38–4.43 (m, 2 H), 7.10–7.35
(m, 10 H). 13C NMR (75 MHz, CDCl3): δ = 35.1, 69.1, 121.0, 121.2,
126.1, 126.4, 126.9, 128.7, 129.1, 129.6, 129.7, 137.1, 151.1,
151.2, 153.7. HRMS (EI): m/z [M+] calcd for C15H14O3: 242.0943;
found: 242.0941.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E