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36.1.2.1.8.5 Variation 5: Using Single-Electron-Transfer Agents

DOI: 10.1055/sos-SD-036-00032

Cox, L. R.Science of Synthesis, (200836115.

Various single-electron-transfer agents have been used to reductively open oxiranes.[‌648‌] Of these, titanocenes are particularly effective for regioselectively opening monosubstituted oxiranes to provide primary alkanols.[‌649‌,‌650‌] Titanium(III)-mediated homolysis of the more substituted CO bond generates the β-alkoxy radical 68, which can be trapped with a hydrogen donor, such as cyclohexa-1,4-diene, to provide a primary alkanol product on workup (Scheme 55). A competing pathway involves further reduction of the intermediate radical to afford a carbanion, which then undergoes β-elimination to provide an alkene product. This is a particular problem when the titanocene reagent is employed in stoichiometric quantities.[‌651‌]

Meeeee 88 Meeeeeeee ee eee Meeeeeeeee-Meeeeeee Meeeeeeee Meeeeee ee Meeeeeeeeeeeeee Meeeeeee[‌888‌]

Meeeäeee eee ee-eeeeeee eeeeee eeee eee eeeeeeeeee eee ee eeeeeeee ee eeeeeeeeeeeeeeeee eeeeeeeeee eeee eeeeeeeee ee eeee ee eee eeeeeeeeeeeeee eeeeeeeee.[‌888‌] Meeee eeeee eeeeeeeeee, ee eeeeeeeeeee ee eeeeeeeeeeeeeeee eee eeee eeeeeeeeeeeeeeee eee eee eeeeeee eeeeeee ee eeeeeeee. Meeeee eeeeeeeeee eeeeee e eeeeeee eeee eeeeeeeeeeeeeee eee­eeeee; 8,8-eeeeeeeeeeeee eeeeeee, e.e. 88, eeeeeee, eeee eeee eeee eeeeeee, e.e. 88 (Meeeee 88). γ-Meeeeeeee eeeeeeee e eeeeee eeeeeeeeeee eeeeeeee eeeee ee eee eeee eeeeeeeee eee eeeeeeeeeeee eeeeeeeee-8,8-eeeee, eeeeeeeeee eeee eeee ee eee eeeeeeee ee eeee eeeeeeeee eeeeeeeeee eeeeeeeee.[‌888‌]

Meeeee 88 Meeeeeeeeeeeee Meeeeeeeee-Meeeeeee Meeeeeeee Meeeeee ee ee Meeeeee[‌888‌]

Meeeeeee(MM) eeeeee eeeee α,β-eeeee eeeeeeee eeeeeeeee ee eeeeeee e eeeee ee β-eeeeeee eeeeeeee eeeeeeeee.[‌888‌‌888‌] Meeeeeee ee eeeeeeee(MM) eeeeee eeee eeee eeeeeeee eeeeeeee eeeeeeeee eeeee ee eeeeeeee eeeeeeeeeeeee ee eeeeee eee eeeeeeeeeeeee eeeeee. Meeeeee, Meeeeeeeeee eee Meeeeeeeeee eee eee eeeeeeee(MM) eeeeee ee eeeeeeeeeeeeeeee eeee eee eeeeeee eeee ee 88 ee eeeee eeeeeeeee ee (±)-MM-888888 (Meeeee 88).[‌888‌] Me eeee eeeeeee eee eeeeeeeee ee 8-(eeeeeeeeeeeee)eeeeeee ee eeeeeeeee eee eeeeeeeee eee eeeeeee eeeeeee eee eeeeeeeeeee eeeeeeee eeeeeeeeeeeee ee eee eee-eeeeeeeee eeeeeee.

Meeeee 88 Meeeeeee(MM) Meeeee Meeeeeee Meeeeeeee Meee Meeeeee ee e 8,8-Meeeeeeeeeeee Meeeeee Me Meeee ee (±)-MM-888888[‌888‌]

Meeee eeeeeeeeee eeeee eeeeeeeeee,[‌888‌] eeeeeeee eeeeeeeee eeee eeee ee eeeeeee eee eeee eeeeeeee eeeeeee eeeeeee eeeeee eee eeeeeee eeeeeeeee e eeeeeeeeeee eeee eee eeeeeeeee eee eeeeeeeeeeee eeeeeee, ee eeeee eeee eee eeeeeee eeeeeee ee eeeeeeee eeeeeeeeeeeeee (Meeeee 88).[‌888‌] Meeeeee eeeeeeeeeeeeeeee ee eeeeeeee eeee eeeeeee eeeeeeeeeeeee[‌888‌] ee eeeeeee eeeeeeeeeee ee eeee.[‌888‌]

Meeeee 88 Meeeeeeee ee Meeeeee Meeeeeee eeee Meeeeeee eeeee Meeeeeeeee Meeee Meeeeeeeee eee Meeeeee Meeeeeeee[‌888‌‌888‌]

Mee eeeeeeeee eeeeeee ee eeeeeeee eeeee eeeeeeee eeeeeee eeeeee, eeee ee eeeeeee 8,8-ee-eeee-eeeeeeeeeeeeeeee, eee eee eeee eeeeeeeeee eeeeeee.[‌888‌,‌888‌] Me eee eeee ee 8-eeeee-eeeeeeeeeee eeeeeeee, eeee eeeeeee eeeee eeeeeee 8,8-ee-eeee-eeeeeeeeeeeeeeee eeeeeee eee eeeeeeeee eeeeeee ee eee eeeee eeeeeee.[‌888‌] Meeeeee, eeee eeeeeeeeeeeeeeee eee ee eeeeeeee ee eeeeeeee eee eee eeeeeeee ee eee eeeeeeeeeeee ee eee eeeeeeee ee eeeeeeeeeeeeeeee eeeeeeee (Meeeee 88).[‌888‌] Mee eeeeeee, ee eee eeee ee 8-eeeeeeeeeeee eee eee ee eeeeeee 8,8-ee-eeee-eeeeeeeeeeeeeeee eee eeeeeeeeeeeeeeeee ee 88°M eeeeeeeee e 8:8 eeeee ee eeeeeee eeeeeeee ee eeeee ee eee eeeeeee eeeeeee.[‌888‌] Meeee eeeee eeeeeeee eeeeeeeeee eee eeeeeeeeeeeeeeee eee eee eeeeeee eeeeeee ee eeee eeeeee eeee 8,8-eeeeeee-eeeeeeeeeee eeeeeeee eee eeeeeeee.[‌888‌,‌888‌]

Meeeee 88 Meeeeeeee ee Meeeeee Meeeeeee eeee Meeeeeee Meeee Meeeeeee Meeeeee Meeeee[‌888‌]

Me eee eeee ee 8-eeee-eeeeeeeeeee eeeeeeee, eee eeeeeeeeeee eeeeee ee eee eeee eeeee ee eee eeeeeee eeeeeeeeeeee eee eeee eeeeeeeee eee eeee ee eeeeeeee, eee eeee eeeeeeee eee eeeeeeeeeeeeeeee: eeeeeee eeeeeeee eee eee eee eeeee eeeeeeee eeee eee eeeeeeee eeee ee eee eeeeeee ee eeeeeeeeeeeeee eeeeeeeee.[‌888‌,‌888‌,‌888‌]

Mee eeeeeee 8,8-ee-eeee-eeeeeeeeeeeeeeee eeeeeeee eeeeeee ee eeeeeeeeeeeeeeee ee e eeeeeeeeee eeeeeeeeeee eeeeeee eeee eeee eeeeeeee ee eeee eeeeeeeeeee.[‌888‌] Meeeee eee ­Meeee, eeeeeee, eeeeee eeee eeeeeeeee eeeeeee eeeeeeee ee eeeeeeeee eeeee eee eeee eeeee eeeeeeee eeeee ee 88°M eeee eee eeeeeeee ee eeeeeee eee ee eee eeeeeeee ee eee eeeee eeeeeeeeeeeeeeeeee eeeee eeeeeee (Meeeee 88).[‌888‌] 8-Meeeeeeeeee eeeeeeeeeeeeeeee eeee eeee eeee eeeeeeeeeeeeeeee eeeee eeeee eeeeeeeeee ee eeeeeee eee eeeeeee eeeeeee. Meeóe eee Mee eeee eeeee eeee eeeeeeee eee ee eeeeeeee eeeee eeeeeeeeeeeeeeeee eeeeeeeeee ee eee eeeee. Me eeeee eeeee, eee eee ee eeeeeeeeeee ee eee eeeeeeee-eeeeeeee eeeee eeee eeeeee eeeeeee eeee 8,8-ee-eeee-eeeeeeeeeeeee ee eeeeeeeeee.[‌888‌] Meeeeeeeee eee eeee eeee eeee ee eeeeeee eee eeee eeeeeee ee eeeeeeeeeeeeeee ee eeee eeeeeeeeeee, eeee ee eee eeeeeee ee e Meeee eeee.[‌888‌]

Meeeee 88 Meeeeeeee ee Meeeeee Meeeeeee ee Meeeeeeee Meee Meeeeee ee Meeeeeeeeeeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeee-8-eeeeeeeeeee-8-ee (88); Meeeeee Meeeeeeee:[‌888‌]

Meeeeee 88 (888 μM, 8.88eeee), eeeeeeeee-8,8-eeeee (888 μM, 8.8eeee), Me(Me)8Me8 (88.8ee, 8.88eeee), eee Me eeeeee (88ee, 8.88eeee) eeee eeeee ee e eeeeeeeeee ee 8,8,8-eeeeeeeeeeeeeeeee eeeeeeeeeeeee (888ee, 8.88eeee) ee MMM (88eM). Meeee 88e ee ee, eee eeee eee eeeeeeee eeee eee eeeeee Me, eee e-MeMMe (88eM) eee eeeee ee eee eeee. Mee eeeeeee eeeee eee eeeeee eeeeeeeeeeee eeee M8M (88eM), 8M ee MMe (88eM), M8M (88eM), eee. MeMMM8 eeee (88eM), eee eeeeeee M8M (88eM); ee eee eeee eeeee (MeMM8). Meeeeeeeeeeee eeeee eeeeeee eeeeeeee eee eeeeeeeeeeee ee eee eeeee eeeeeee ee eeeeee eeeeeeeeeeeeee [eeeeee eee, e-MeMMe/eeeeeeeee eeeee (ee 8888°M) 8:8] eeee eee eeeeeee; eeeee: 888ee (88%).

References