Synthesis of Aldehydes from Oxiranes using Silica Gel as Reagent

Gold catalysis: benzanellation versus alkylidenecyclopentenone synthesis

“…11 To a solution of the alcohol 4a (2.00 g, 17.8 mmol) in DCM (100 mL) was added DMP (9.63 g, 19.6 mmol). The raw product of 5a was obtained as a yellow oil ( 12 To a solution of ethynylmagnesium chloride (22.7 mL, 0.6 M solution in THF/toluene, 13.6 mmol) in THF (20 mL) was added a solution of 5a (1.00 g, 9.08 mmol) in THF (20 mL 3.05 (dd, J¼15.0, 6.7 Hz, 1H), 3.11 (dd, J¼15.0, 5.7 Hz, 1H), 4.62-4.70 (m, 1H), 6.21 (ddt, J¼3.2, 0.9, 0.8 Hz, 1H), 6.33 (dd, J¼3.2, 1.9 Hz, 1H), 7.37 (dd, J¼1.9, 0.9 Hz, 1H). 13 13 To a solution of the alcohol 4b (1.45 g, 11.6 mmol) in DCM (80 mL) was added DMP (5.41 g, 12.8 mmol).…”

Nucleophilic Organic Base DABCO-Mediated Chemospecific Meinwald Rearrangement of Terminal Epoxides into Methyl Ketones

“…2-(Thiophen-2-yl)oxirane (1q). 38 Colorless liquid, 248 mg, 98% yield. R f = 0.35, 20% ethyl acetate in petroleum ether.…”

Glass Wool Catalysed Regioselective Isomerization of Styrene Oxides

“…It is interesting to note that synthesis of aldehydes from oxiranes using silica gel as reagent is known under liquid phase conditions. 16 We have attempted styrene oxide isomerization under reflux conditions as such without any catalyst (194-196°C) and also in presence of ceramic beads and glass wool separately. We did not observe any rearrangement and obtained the starting material as such in all the cases, indicating that styrene oxide was stable under reflux conditions and in presence of these materials.…”