Fig. 4: Representative derivatization and a formal synthesis of (±)-alloyohimbane.
From: A facile synthesis of α,β-unsaturated imines via palladium-catalyzed dehydrogenation
Conditions (a) 2 (0.20 mmol), diisobutylalumium hydride (0.30 mmol), THF, −78 °C to rt, 12 h; (b) 2 (0.20 mmol), (phenylethynyl)magnesium bromide (0.60 mmol), Et2O, −20 °C to rt, 12 h; (c) 2 (0.20 mmol), [1,1’-biphenyl]−4-ylmagnesium bromide (0.60 mmol), Et2O, −20 °C to rt, 12 h; (d) 2 (0.20 mmol), dimethyl malonate (0.60 mmol), La(OTf)3 (0.02 mmol), Ph-PyBox (0.02 mmol), 4 Å MS, DCM, 60 °C, 12 h; (e) 2 (0.20 mmol), allylmagnesium chloride (0.60 mmol), Et2O, −20 °C to rt, 12 h; (f) 2 (0.20 mmol), [(trimethylsilyl)methyl]magnesium chloride (0.60 mmol), Et2O, −20 °C to rt, 12 h; (g) 2 (0.20 mmol), benzylmagnesium chloride (0.60 mmol), Et2O, −20 °C to rt, 12 h; (h) 2 (0.20 mmol), ethoxyethene (2.0 mmol), 2,2,2-trifluoroethanol, 50 °C, 24 h; (i) 2 (0.20 mmol), styrene (2.0 mmol), hexafluoroisopropanol, 110 °C, 24 h. TFA, trifluoroacetic acid; Boc, t-Butyloxycarbonyl; Ms, methanesulfonyl.
