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1 Electronic Supplementary Material (ESI) for ChemComm. This journal is The Royal Society of Chemistry 2016 Synthesis of cyclic carbonates from diols and C 2 catalyzed by carbenes Felix D. Bobbink,* Weronika Gruszka,* Martin Hulla, Shoubhik Das and Paul J. Dyson * the authors contributed equally to this work Institut des sciences et ingénierie chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland) paul.dyson@epfl.ch Supporting Information Table of contents: I) General remarks II) Catalytic procedure III) Yield comparison with recently reported studies..3 IV) Mechanistic study....4 V) Characterization of isolated compounds and spectra....6 VI) References..9 1

2 I) General remarks All reagents and solvents were purchased from commercial sources and used as received without further purification. Dry solvents from Acros were used throughout the experiments. In order to avoid water contamination all chemicals were stored in a dry glovebox. The reaction is very water sensitive and yields decrease if lower quality solvents or bench-stored Cs 2 C 3 are used. The GC-MS/FID were recorded on a Gas Chromatograph Agilent 7890B equipped with an Agilent 7000C MS triple quad detector and a capillary column from Agilent (l x d x f: 25 m x 0.25 mm x 0.25 μm) using N 2 as carrier gas. 1 H and 13 C NMR spectra were recorded on a Bruker 400 MHz instrument. II) Catalytic procedure Typical procedure for the synthesis of cyclic carbonates: In a dry glovebox, a three-neck flask was charged with the starting material (0.5 mmol), base ( mmol) and the imidazolium/thiazolium salt (0.1 mmol). The flask was then removed from the glovebox and connected to a Schlenk line and a C 2 -filled balloon. Three vacuum and C 2 -purge cycles were performed, and then alkyl halide ( mmol) and solvent (4 ml) were added to the system. The reaction was heated in an oil bath at the desired temperature and the reaction mixture stirred for the appropriate time. After reaction, the mixture was diluted with EtAc (5-10 ml) and the crude mixture was analysed by GC-MS using decane as an internal standard. Yields were determined by GC-FID. For the isolated yields, an aqueous work-up was performed and the product was obtained by column chromatography using pentane:etac as an eluent (100:0 to 70:30). 2

3 III) Yield comparison with recently reported studies Table S1. Yield comparison in several recent publications. Substrate Methodology Yield of cyclic carbonate (%) This work SG SG SG SG (0.5 mmol), DBU (1 mmol), [Bmim][PF 6 ] (0.1 ml), CH 2 Br 2 (0.5 M), 70 C, C 2 (10 bars), 18 h SG (2.5 mmol), C 4 H 9 Br (24 mmol), DBU (20 mmol), DCE (1 ml), 25 C, C 2 (1 atm.), 24 h SG SG (10 mmol), Ce 2 (2 mmol), C 6 H 4 N 2 (100 mmol), 180 C, C 2 (50 bars), 1 h This work (0.5 mmol), DBU (1 mmol), [Bmim][PF 6 ] (0.1 ml), CH 2 Br 2 (0.5 M), 70 C, C 2 (10 bars), 18 h (2.5 mmol), C 4 H 9 Br (24 mmol), DBU (20 mmol), DCE (1 ml), 25 C, C 2 (1 atm.), 24 h (10 mmol), Ce 2 (2 mmol), C 6 H 4 N 2 (100 mmol), 180 C, C 2 (50 bars), 1 h (60 mmol), Zn(Tf) 2 (3 mmol), MeCN (10 ml), 135 C, C 2 (40 bars), 16 h (100 mmol), K 2 C 3 (5 mmol), PhCN (100 mmol), 175 C, C 2 (100 bars), 18 h H H H H 1-phenyl-1,2-ethanediol (SG) propylene glycol () 3

4 IV) Mechanistic study Table S2. Control experiments. Entry Cat. Bu-Br (2 eq or 5 eq) Cs 2 C 3 (3.2 eq) C 2 (1 bar) Yield (%) [b] 1 Yes Yes Yes Yes 81 2 Yes Yes Yes No 25 3 No Yes Yes Yes 53 4 Yes No Yes Yes 0 5 Yes Yes No Yes 0 6 a Yes Yes Yes Yes 0 Conditions: diol (0.5 mmol), cat (20 mol%), n Bu-Br (1-2.5 mmol), Cs 2 C 3 (3.2 eq), DMF (4 ml), C 2 (1 bar). 90 C, 24 h. a : 5 mmol H 2 is added to the reaction. obs. by GC-MS a) Br Cs Cs + Bu Bu b) obs. by GC-MS R Bu -BuH R obs by GC-MS Scheme S1. bserved intermediates from the non-catalytic pathway. The first step (a) can be promoted by the solvent (see Y. R. Jorapur, D. Y. Chi, J. rg. Chem. 2005, 70, ). The second step (b) represents step 4 in Scheme 2. 4

5 Fig S1. Comparison between 13 C NMR of unlabelled and labelled styrene carbonate. 5

6 V) Characterization of isolated compounds and spectra 4-phenyl-1,3-dioxolan-2-one: 1 H NMR (400 MHz, Chloroform-d) δ (m, 3H), (m, 2H), 5.70 (t, J = 8.0 Hz, 1H), 4.82 (t, J = 8.4 Hz, 1H), (m, 1H); 13 C NMR (101 MHz, CDCl 3 ) δ 154.8, 136.2, 129.7, 129.2, 125.8, 78.0, ,5-diphenyl-1,3-dioxolan-2-one: 1 H NMR (400 MHz, Chloroform-d) δ (m, 6H), (m, 4H), 5.46 (s, 2H); 13 C NMR (101 MHz, CDCl 3 ) δ 154.0, 134.9, 129.8, 129.2, 126.1,

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9 VI) References 1 Y. N. Lim, C. Lee and H. Y. Jang, Eur. J. rg. Chem., 2014, 2014, T. Kitamura, Y. Inoue, T. Maeda and J. yamada, Synth. Commun., 2016, 46, M. Honda, M. Tamura, K. Nakao, K. Suzuki, Y. Nakagawa and K. Tomishige, ACS Catal., 2014, 4, J. W. Comerford, S. J. Hart, M. North, A. C. Whitwood, Catal. Sci. Technol. 2016, 6, E. Da Silva, W. Dayoub, G. Mignani, Y. Raoul, M. Lemaire, Catal. Commun. 2012, 29,