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Please login or sign up for a free trial to access the full content. Method 3: Organomagnesium Hydrides as Reducing Agents

DOI: 10.1055/sos-SD-007-00466

Zhang, J.-H.; Keh, C. C. K.; Li, C.-J.Science of Synthesis, (20047515.

As mentioned earlier, magnesium hydride (1) can be converted into other magnesium hydride derivatives such as organomagnesium hydrides, which are also useful reducing agents. For example, cyclopentadienylmagnesium hydride is prepared by the reaction of magnesium hydride (1) either with bis(cyclopentadienyl)magnesium[‌13‌] or with cyclopentadiene in tetrahydrofuran,[‌14‌] and can reduce aromatic ketones, polynuclear hydrocarbons, and trityl halides through a single-electron-transfer mechanism. The alkoxymagnesium hydride 2,6-(diisopropylphenoxy)magnesium hydride (7) has been employed in the stereoselective reduction of substituted cyclohexanones 6 to the corresponding alcohols 8A and 8B in excellent yields. When magnesium hydride 7 is used, more of cyclohexanol 8A, the product from equatorial attack, forms than when magnesium hydride (1) is used (Scheme 4).[‌15‌]

Meeeee 8 Meeeeeeeeeeeeee Meeeeeeee ee Meeeeeeeeeeee Meeeeeeeeee ee 8,8-(Meeeeeeeeeeeeeeeee)eeeeeeeee Meeeeee ee Meeeeeeee Meeeeee[‌88‌]

Meeeeeeeeee 8

M8 Meeeeeee Meeee Meeee (8M/8M) Meeee (%) Mee
8-Me MeM8 (8) 88:88 888 [‌88‌]
8-Me 8 88:8 888 [‌88‌]
8,8,8-Me8 MeM8 (8) 88:88 88 [‌88‌]
8,8,8-Me8 8 88.8:8.8 888 [‌88‌]
8-e-Me MeM8 (8) 88:88 888 [‌88‌]
8-e-Me 8 88:88 888 [‌88‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeeeeeeeeeeeeeee (8, M8=8-Me); Meeeeee Meeeeeeee:[‌88‌]

Me e eeee-eeeeeee eeeeee ee MeM8 (8; 8.88e, 8.8eeee) ee MMM (88eM) ee 88°M eee eeeee eeeeeeee e eeee ee 8,8-eeeeeeeeeeeeeeeee (8.88e, 8.8eeee) ee MMM (88eM). Mee eeeeeee eee eeeeeee ee eeee ee ee eee eeeeeee eee 8e ee eeee e eeeee eeee ee 8,8-(eeeeeeeeeeeeeee­eee)­eeeeeeeee eeeeeee (8; ee. 8.8eeee). Meee eee eeeee ee e eeee-eeeeeee eeee ee 8 (M8=8-Me; 8.88e, 8.8eeee) ee MMM eeeee M8, eeee eeeeeeee ee ee eeeeeeee eeeeeeee. Meeee 88e, eee eeeeeee eee eeeeee eeeeeeee eeee M8M eee eeeee (MeMM8). Meeeeeeeeeee 8 eee eeeeeeee ee e eeeeeee ee eee M- eee M-eeeeeeee 8M eee 8M [(8M/8M) 88:8], eeeee eeee eeeeeeeee ee eeeeeeeeeeeeee (Meeeeeeeee M eeeeee, 8.8 e, 88% eeeeeeeeee); eeeee: 8.88e (888%).