.
Angewandte
Communications
(m, 4H), 7.34–7.43 (m, 3H), 7.69–7.73 ppm (m, 2H); 13C NMR: d =
21.5, 50.3, 72.4, 85.0, 124.2, 126.9, 129.2, 129.9, 136.5, 138.1, 143.9,
154.2 ppm; HRMS (ESI+): Calcd for C17H18NO5S, [M+H]+ 348.0900,
found m/z 348.0892. Elemental analysis calcd for C17H18NO5S: C,
58.78; H, 4.93; N, 4.03; O, 23.03; S, 9.23; found: C, 58.71; H, 4.96; N,
3.89; O, 22.84; S, 9.32; IR (ATR): 3261, 1773, 1435, 1319, 1045 cmÀ1
.
Received: August 1, 2012
Published online: November 6, 2012
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Keywords: C H activation · carbon dioxide · photochemistry ·
photosynthesis · strained molecules
.
[1] N. Armaroli, V. Balzani, Energy for a Sustainable World, From
the Oil Age to a Sun-Powered Future, Wiley-VCH, Weinheim,
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Pampaloni, Chem. Rev. 2003, 103, 3857; b) T. Sakakura, J.-C.
Chemical Feedstock (Ed.: M. Aresta), Wiley-VCH, Weinheim,
C. Bruckmeier, B. Rieger, W. A. Herrmann, F. E. Kꢁhn, Angew.
Scheme 5. Scope of solar-driven CO2 incorporation into a-amino
ketone 1. Overall yields of isolated products are given. Reactions were
conducted on a 0.2 mmol scale with the following reagents and
conditions: 1 (0.20 mmol), DMA (1.0 mL), solar light, ambient temper-
ature, CO2 (1 atm); then Cs2CO3 (0.80 mmol), 608C. See the Support-
ing Information for full experimental details.
[4] For selected examples of carbonate formation using CO2, see:
a) P. Dimroth, H. Pasedach, Ger. 1098953, 1961; b) T. Fujinami,
[6] K. B. Winberg, Angew. Chem. 1986, 98, 312; Angew. Chem. Int.
Ed. Engl. 1986, 25, 312.
[7] a) Activation of Unreactive Bonds and Organic Synthesis (Ed.: S.
Murai), Springer, Berlin, 1999; b) Handbook of C-H Trans-
formations (Ed.: G. Dyker), Wiley-VCH, Weinheim, 2005;
energy during the former reaction, assist in the fixation of
CO2, which is intrinsically low in energy. Photosynthesis as
a whole reduces CO2 into carbohydrates. Although the
present consecutive process does not involve CO2 reduction,
its mechanistic profile of energy resembles that of photosyn-
thesis and presents a simple model of the chemical utilization
of solar energy for CO2 incorporation.
Experimental Section
A typical procedure for the one-pot reaction of a-amino ketone 1a
with carbon dioxide: a-Amino ketone 1a (30.3 mg, 0.10 mmol) was
placed in a Pyrex tube. The vessel was subsequently filled with CO2
(1 atm) by vacuum–refill cycles (three times), and N,N-dimethylacet-
amide (1.0 mL) was added therein. The mixture was exposed to solar
light outside for eight hours. After completion of the photochemical
reaction, Cs2CO3 (130 mg, 0.40 mmol) was added to the reaction
mixture, which was then stirred at 608C in a fume hood. After ten
hours, the reaction mixture was treated with HCl aq. (2.0m) and the
aqueous layer was extracted with Et2O (three times). The combined
organic layer was washed with water (three times) and brine (once),
dried over MgSO4, and concentrated. The residue was purified by
preparative thin-layer chromatography on silica gel (hexane/ethyl
acetate = 3:1) to afford the analytically pure carbonate 3a (28.8 mg,
0.083 mmol, 83% yield). 1H NMR: d = 2.40 (s, 3H), 3.30 (dd, J = 14.4,
5.6 Hz, 1H), 3.40 (dd, J = 14.4, 8.8 Hz, 1H), 4.54 (d, J = 8.4 Hz, 1H),
5.08 (d, J = 8.4 Hz, 1H), 5.70 (dd, J = 8.4 Hz, 5.6 Hz, 1H), 7.26–7.32
À
c) For a special issue on selective functionalization of C H
bonds, see: Chem. Rev. 2010, 110, 575 (Ed: R. H. Crabtree).
[10] P. J. Wagner, J. H. Seldon, A. Gudmundsdottir, J. Am. Chem.
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 11750 –11752