10.1002/cssc.201900406
ChemSusChem
FULL PAPER
order to remove the last traces of solvent and to obtain pure 4-
(ARBOREF), UAntwerpen (IOF, BOF), the Hercules foundation, and the
BIO-HArT project which is established by a contribution of the European
Interreg V Flanders-The Netherlands program that stimulates innovation,
sustainable energy, a healthy environment and the labor market by
means of cross-border projects. We thank Prof. Christophe Vande Velde
(University of Antwerp) for thermogravimetric analysis.
propylbenzene-1,2-diol (2) as an off-white solid (29.6 g, 97%).
Synthesis of 4-propylcatechol carbonate (3a)
A 500 mL 3-necked roundbottom flask equipped with a stirring bar, an
adaptor with side arm bearing 4 Å molecular sieves (8-12 mesh) and a
reflux condensor is charged with 4-propylbenzene-1,2-diol (2) (25.0 g,
164.0 mmol, 1 equiv,), sodium methoxide (0.293 g, 5.42 mmol, 0.033
equiv) and dimethyl carbonate (518 g, 484 mL, 5749.0 mmol, 35 equiv).
The mixture is stirred under argon atmosphere and heated to reflux (oil
bath) for 28 h. Afterwards, the crude reaction mixture is cooled to room
temperature, and diluted with 200 mL MTBE. The resulting mixture is
filtered over a plug of celite. The filtrate is washed with 200 mL aqueous
HCl (1M), and the organic phase dried over anhydrous MgSO4, filtered
and evaporated to dryness. The residue was purified using automated
flash chromatography (SiO2, 80 g cartridge, 100% heptane to 98%
heptane/2% EtOAc over 60 min, 30 mL/min) to give the title compound
(3a) as a colorless liquid (25.2 g, 86%).
Keywords: C1 reactant • catechol carbonate • renewable •
carbamate • Zn catalysis
[1] Road Map Document for a Sustainable Chemical Industry, Energ-Ice,
2013.
[2] O. Kreye, H. Mutlu, M. A. R. Meier, Green Chem. 2013, 15, 1431-1455.
[3] J. H. Clark, Nature Chem. 2009, 1, 12-13.
[4] L. Cotarca, H. Eckert in Phosgenations: A Handbook, John Wiley & Sons,
2006.
[5] OPCW. (2019). Chemical Weapons Convention. [online] Available at:
2019].
5 Feb.
[6] S. B. Damle, Chem. Eng. News 1993, 71, 4-5.
[7] A. K. Gosh, M. Brindisi, J. Med. Chem. 2015, 58, 2895-2940.
[8] P. G. M. Wuyts in Greene's Protective Groups in Organic Synthesis, 5th
Ed., John Wiley & Sons, 2014.
Synthesis of alkyl 2-hydroxy-5-propylphenyl carbonate and alkyl 2-
hydroxy-4-propylphenyl carbonate (5)
[9] J. lzdebski, D. Pawlak, Synthesis 1989, 21, 423-425.
[10] D. Pereira, T. ThatHai, D. Nelson, Synth. Commun. 1998, 28, 4019-4024.
[11] K. Sunggak, I. L. Jae, K. K. Young, Tetrahedron Lett. 1984, 25, 4943-
4946.
A 10 mL vial, equipped with a stirring bar, was charged with 4-
propylcatechol carbonate (3a) (1 equiv), alcohol (3 equiv) and
Zn(OAc)2·2H2O (1 mol%). In case of solid alcohol 2-MeTHF was added
(1M). The vial was sealed with an aluminum crimp cap with septum. The
reaction mixture was then stirred at 50 °C for 16 h (primary alcohols) or
80 °C for 16 h (secondary alcohols). Afterwards the mixture was cooled
to room temperature, dissolved in a small amount of toluene and
transferred directly to a silica cartridge via a syringe for purification.
[12] M. Peña-López, H. Neumann, M. Beller, ChemSusChem 2016, 9, 2233-
2238.
[13] Q. Zhang, H.-Y. Yuan, N. Fukaya, H. Yasuda, J.-C. Choi,
ChemSusChem 2017, 10, 1501-1508.
[14] a) P. Tundo, M. Musolino, F. Aricò, Green Chem. 2018, 20, 28-85; b) G.
Fiorani, A. Perosa, M. Selva, Green Chem. 2018, 20, 288-322.
[15] For recent examples of transesterifications with DMC, see: a) S. Van
Mileghem, W. M. De Borggraeve, I. R. Baxendale, Chem. Eng. Technol.
2018, 41, 2014-2023; b) Q. Gu, J. Fang, Z. Xu, W. Ni, K. Kong, Z. Hou,
New J. Chem. 2018, 42, 13054-13064; c) S. Ramesh, K. Indukuri, O.
Riant, D. P. Debecker, Org. Process Res. Dev. 2018, 22, 1846-1851.
[16] H.-Z. Tan, Z.-Q. Wang, Z.-N. Xu, J. Sun, Y.-P. Xu, Q.-S. Chen, Y. Chen,
G.-C. Guo, Catal. Today 2018, 316, 2-12.
Purification of
5
was carried out using an automated flash
chromatography system with a solvent system as specified for the
specific compound.
Synthesis of carbamates (8)
[17] a) Y. Hartadi, D. Widmann, R. J. Behm, ChemSusChem 2015, 8, 456-
465; b) J. Kothandaraman, A. Goeppert, M. Czaun, G. A. Olah, G. K.
Prakash, J. Am. Chem. Soc. 2016, 138, 778-781.
A 10 mL vial, equipped with a stirring bar, was charged with the
appropriate carbonate 5 (1 equiv), and 2-MeTHF (1M). Afterwards the
appropriate amine 7 (1.5 equiv) was added. The vial was sealed with an
aluminum crimp. cap with septum. The reaction mixture was then stirred
at 25 °C for 16 h. After reaction, the crude was diluted with (30 mL/mmol
MTBE, washed with 3x9 mL/mmol aqueous NaOH (1M), 2x9 mL/mmol
aqueous HCl (1M), 1x9 mL/mmol saturated NaHCO3 solution, and with
1x9 mL/mmol brine. The organic phase was dried over anhydrous
MgSO4, filtered and evaporated to dryness yielding the desired
carbamate 8. In order to recover 4-propylcatechol (2), the NaOH phase
was acidified with 35 mL/mmol aqueous HCl (1 M) and extracted with
3x10 mL/mmol MTBE. The organic phase was washed with brine, dried
over anhydrous MgSO4, filtered, and evaporated to dryness to give 2.
[18] T. Zhao, X. Hu, D. Wu, R. Li, G. Yang, Y. Wu, ChemSusChem 2017, 10,
2046-2052.
[19] a) P. Tundo, M. Selva, Acc. Chem. Res. 2002, 35, 706-716; b) M.
Litwinowicz, J. Kijeński, Sus. Chem. Proc. 2015, 3, 1-7.
[20] For some examples on the methoxycarbonylation of amines, see: a) M.
Curini, F. Epifano, F. Maltese, O. Rosati, Tetrahedron Lett. 2002, 43,
4895-4897; b) H. Zhou, F. Shi, X. Tian, Q. Zhang, Y. Deng, J. Mol. Catal.
Chem. 2007, 271, 89-92.
[21] J. Gong, X. Ma, S. Wang, Appl. Catal. Gen. 2007, 316, 1-21.
[22] For some examples, see: a) R. H. Yu, R. P. Polniaszek, M. W. Becker, C.
M. Cook, L. H. L. Yu, Org. Proc. Res. Dev. 2007, 1, 972-980; b) I. F.
Sevrioukova, T.L. Poulos, J. Med. Chem. 2013, 56, 3733-3741.
[23] T. Tabanelli, S. Cailotto, J. Strachan, A. F. Masters, T. Maschmeyer, A.
Perosa, F. Cavani, Catal. Sci. Technol. 2018, 8, 1971-1980.
[24] A new procedure for the synthesis of cyclic carbonates using diphenyl
carbonate as C1 reactant was recently published. Applying this
procedure on 2 resulted in 85% of 3a: E. R. Baral, J. H. Lee, J. G. Kim, J.
Org. Chem. 2018, 83, 11768-11776.
Acknowledgements
The authors acknowledge the financial support from the Research
Foundation Flanders (FWO) (Research Project and Excellence of
Science project (BioFact, Grant n°30902231)), VLAIO/Catalisti
[25] S. Zhao, M. M. Abu-Omar, Biomacromolecules 2015, 16, 2025-2031.
This article is protected by copyright. All rights reserved.