Diethyl Ether → 2,2,3,3,9,9-Hexamethyl-4-oxa-3,9-disiladec-5-ene

Participants

Reaction Conditions

Reaction Steps

A dried reaction flask equipped for magnetic stirring was flushed with nitrogen and charged with a 1 F solution of (trimethylsilylmethyl)magnesium chloride in diethyl ether (300 ml, 300 mmol). Diethyl ether was distilled under reduced pressure. The resulting neat Grignard reagent was dissolved in 500 mL of dry tetrahydrofuran, the solution was cooled to −78 ° C., and copper(I) bromide-dimethyl sulfide complex (2.16 grams, 10.5 mmol, available from Aldrich Chemical Company, Inc., Milwaukee, Wis.) and hexamethylphosphoramide (100 grams, 560 mmol, available from Aldrich Chemical Company, Inc.) were added to the reactor with stirring. Acrolein (14.1 mL, 11.8 grams, 210 mmol, available from Aldrich Chemical Company, Inc.) dissolved in a 1 M solution of tert-butyldimethylsilyl chloride (300 mL, 300 mmol, available from Aldrich Chemical Company, Inc.) in tetrahydrofuran was added dropwise to the cooled reaction mixture, with stirring, over a period of 3 hours. After an additional 2 hours reaction time, triethylamine (42.0 mL, 30.5 grams, 300 mmol, available from Aldrich Chemical Company, Inc.) was added, and the reaction mixture was subsequently allowed to warm to room temperature. The reaction mixture was diluted with pentane (1 L), water (50 mL) was added, and the mixture was transferred to a separatory funnel. The organic phase was separated from the aqueous phase and washed with water (ten×50-mL portions) to remove hexamethylphosphoramide. The combined aqueous washes were extracted once with pentane (100 mL), and the combined organic phases were washed once with a saturated aqueous sodium chloride solution (100 mL) and dried over magnesium sulfate. The mixture was filtered, and the filtrate was concentrated in a rotary evaporator under reduced pressure. Vacuum distillation of the residue afforded 2,2,3,3,9,9-hexamethyl-4-oxa-3,9-disiladec-5-ene as a clear, colorless liquid (49.6 grams, 91 percent). The 1H, 13C, and 29Si NMR spectra of the product were consistent with a 10:1 mixture of the E and Z stereoisomers of 2,2,3,3,9,9-hexamethyl-4-oxa-3,9-disiladec-5-ene.

Provenance & Evidence