PREPARATION AND CHARACTERIZATION OF ALKOXY(AROXY)MAGNESIUM HYDRIDES

A series of alkoxy- and aroxymagnesium hydrides (HMgOR, where R=Me, i-Pr, t-Bu, t-BuCH2, PhCH2CH2, c-C6H11, Ph, Ph3C, Ph2(Me)C, 2, 6-Me2C6H3, 2, 6-i-Pr2C6H3, and 2, 6-t-Bu2-4-MeC6H2) has been synthesized by the redistribution of bis(alkoxy or aroxy)magnesium compounds with magnesium hydride in tetrahydrofuran. These compounds were also prepared by the reaction of magnesium hydride with the appropriate alcohol at -78 °C followed by warming the reaction mixture to room temperature. Some of the HMgOR compounds where R=PhCH2CH2, c-C6Hu, Ph3C, Ph2(Me)C, 2, 6-Me2C6H3, 2, 6-i-Pr2C6H3, and 2, 6-t-Bur4-MeC6H2 were found to be THF soluble. Interestingly, THF-soluble cyclohexoxymagnesium hydrides could be prepared easily by the reduction of cyclohexanones with magnesium hydride in THF. All hydrides were characterized by elemental analysis, infrared and NMR spectroscopies, ebullioscopic molecular weight studies, X-ray powder diffraction, and vacuum DTA-TGA. Assignments of Mg-H stretching and bending modes have been made by comparison with the corresponding deuterated compounds. The products have been shown to be excellent stereoselective reducing agents toward ketones. © 1979, American Chemical Society. All rights reserved.