N. Guttenberger et al.
dissolving 999.2 mg of 9 (3.53 mmol) in 70 cm3 MeOH
and transferred into a 150 cm3 beaker. For the reduction
itself a continuous-flow hydrogenation reactor (H-cubeÒ)
with a 10% Pd/C catalyst cartridge was used with the
following conditions: 1.0 cm3 min-1, rt, atmospheric
pressure, full H2. The reaction was stopped after multiple
runs (ca. 6 times, 8 h). The product solution was
transferred into a 250 cm3 round-bottom flask and the
solvent was removed in vacuo and 995 mg (99%) of 14
was isolated as colorless solid. Rf = 0.73 (cyclohexane/
EtOAc = 2/3, KMnO4); m.p.: 113–115 °C; 1H NMR
(300 MHz, CDCl3): d = 4.72 (m, 2H), 4.25 (d,
J = 4.9 Hz, 1H), 4.18 (q, J = 7.1 Hz, 2H), 2.15 (d,
J = 4.7 Hz, 1H), 1.92–1.75 (m, 2H), 1.75–1.47 (m, 3H),
1.43 (s, 9H), 1.26 (t, J = 7.1 Hz, 3H) ppm; 13C NMR
(76 MHz, CDCl3): d = 172.2, 155.6, 79.8, 78.5, 77.4,
61.3, 56.2, 55.2, 30.2, 28.4, 22.5, 14.3 ppm (2 peaks are
missing).
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Acknowledgements Open access funding provided by Graz
University of Technology. We are indebted to Prof. Wulf Blanken-
feldt (Helmholtz-Centre for Infection Research, Braunschweig) for
our longstanding and fruitful collaboration in the Chemical Biology
of phenazine biosynthesis. We thank the Austrian Science Fund
(FWF, Project I-668) for financial support, Karin Bartl, Robert Saf,
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˚
and Pal William Wallace for HRMS measurements, Carina Ill-
aszewicz-Trattner and Jorg Weber for assistance in NMR
¨
measurements, and Nikolaus Turrini for helpful discussions.
123