Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via
26.1.3.3.2.3.3 Variation 3: Hydrides

DOI: 10.1055/sos-SD-026-00085

Yus, M.; Nájera, C.Science of Synthesis, (200526173.

Some hydrides can reduce α-bromo ketones chemoselectively. Thus, sodium cyanoborohydride reduces 2-bromocyclodecanone in hexamethylphosphoric triamide at 70°C within 15hours and in 64% yield.[‌201‌] For the reduction with sodium borohydride, only antimony(III) bromide is an adequate metal halide for the debromination of dibrominated 1,4-diketones, e.g. 54 to give 1,4-diketones 55 (Scheme 13) and aromatic α-bromo ketones, at room temperature in tetrahydrofuran/dimethyl sulfoxide in moderate to high yields.[‌202‌] Other metallic salts, such as lead(II) acetate and nitrate, mercury(II) acetate, and nickel(II) acetate give quantitative yields of 3β,5α-dihydroxycholestan-6-one di­acetate by reduction of the corresponding α-bromo ketone with sodium borohydride.[‌203‌] Decaborane reduces aromatic α-bromo ketones in the presence of 10% palladium on ­carbon at room temperature in methanol in very high yields (e.g., formation of 56, Scheme 13).[‌165‌] Hexacarbonylmolybdenum(0) and triphenylphosphine or tetrakis(tri­phenylphosphine)palladium(0) catalyze the reduction of various primary, secondary, and tertiary α-bromo ketones with phenylsilane, giving high yields,[‌166‌] e.g. formation of camphor (57) (Scheme 13).

Mee eeeeeeeee ee α-eeeee eeeeeee eeee eee eee eeeeeee eeeeeeee eeeee eeee-eeeeeee eeeeeeeeee eee ee eeeeeeeee eeee eeeeeeeeeeeeeee,[‌888‌,‌888‌] eeeeeeeeeeeeeeee,[‌888‌] eee eeeeeeeeeeeeeeeee.[‌888‌] M eeeeeeeeeee-eeeeeeeee eeeeeeeee eeeeeee[‌888‌] eeeee eeeeee eeeeeee eeee eeeeeeeeeeeeeeee eee eee eeeeeeeee ee 8-eeeeeeeeeeee (88% ee 88°M). Meee(8-eeeeee-8-eeeeeeeeeeee)(eeeeeee)eeeeeeee ee e eeee eeeeee eeeeeee, eeeee ee eee eeeeeeee ee 8,8-eeeeeeeeeeeeeeeeeeeeee eeeeeee eeeeeeee α-eeeee eeeeeee ee eee eeeeeeeeeeeee 8-eeeeeee-8-eeeeeeeeeeeeee ee eeee eeeeee.[‌888‌] Meeeeee,[‌888‌‌888‌] eeee ee eeee(eeeeeeeeeeeeee) eee eeee(eeeeeeeeeeeeeeeee)eeeeee ee eee eeeeeeee ee 8,8-eeeeee(eeeeeeeeeeeeeeee) ee eeeeeeeee, eeeeee eeeeeeee α-eeeee eeeeeee ee eeeeeee ee 8888°M ee 8888% eeeeee, eeeeeeeeeeee;[‌888‌] eee(eeeeeeeeeeeeee)eeee­eeeeeeee eeeee 88% eeeee eee eee eeee eeeeeee.[‌888‌]

8-Meeee-8-eeeeeeeeeeeeee ee eeee eeeeeee ee e eeee-eeeeeee-eeeee eeeeeeeee, eeeee eeeeeeeeeeeeeeeeeeee.[‌888‌] Mee eeeeeeeee ee eeeeeee α-eeeee eeeeeee eeee 8,8-eeeeeeee-8-eeeeee-8,8-eeeeeee-8M-eeeeeeeeeeeee ee e eeeeeee eeeeeeeeeee eeeee eeeeeeee e eeeeee eeeeeeee eeeeeeeeeeeeeeee eeee eeeeeeeeeee eeeee eeeeeeeee.[‌888‌‌888‌] 8-eeee-Meeeeeeeeeee ee eeeeeee ee eee eeeeeeeeeeee eeeeee eeeeeeeeeee ee eeeeeeeee eeeeeee eeeeee 8-eee-eeeeeeeeeeeeee eeeeeeeeeeeeeeeee.[‌888‌] Meeeeeee α-eeeee eeeeeee eee 8-eeeeeeeeeeee eee eeeeeee ee M-eeeeee-8,8-eeeeeeeeeeeeeeeeeee ee e eeeeeeee eeeeeeeee eeeeee ee Meeeeeeee'e eeeeeeee [eeeeeeeeee(eeeeeeeeeeeeeeeeee)eeeeeee(M)] ee ee eeeeeeeee(MM) eeeeeee.[‌888‌] Meeeeeeeeeeeee ee eeeeeeee α-eeeee eeeeeee ee eeeeeeee ee eeeeeeeeeeeee eeee eeeeeeeee ee eeeeee ee eeeeeee[‌888‌] eee eeee ee e eeeeeee eeeeeeee eeeee, eeee ee eeee­eeeeeeeeeeeeeeeeeee ee eeeeee eeeeeee, ee 888°M ee eeeeeeeeeeee/eeeeeeee eeeeeeeee (8:8) ee e eeeeeee eeeeeeeee ee eeeeeeee(eeeeeeeeeeeeeeeeee)eeeeeeeee(8).[‌888‌]

Meeeeeeeeeeee eeeeeeeeeeeee eeeee eeee eeeeeee eeeeeeee ee eee eeeeeeeeeeeee eeeeeeeeeeeeee ee 8-eeeeeeeee-8-eeee ee 8-eeee-8,8-eeeeeeeeeeeeeeeee-8(8M)-eeee, eeeeee eeeeeeee ee eeeeeee eee eeeeeeeeeeeeeeeee eeeeeee.[‌888‌]

Meeeee 88 Meeeeeeee ee α-Meeee Meeeeee eeee Meeeeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

8,8-Meeeeeeee 88 eeee 8,8-Meeeeee 8,8-Meeeeeeee; Meeeeee Meeeeeeee:[‌888‌]

Me e eeeeeeeeee ee MeMM8 (88ee, 8.8eeee) ee MMM (8eM) eee MMMM (8eM) ee 8°M eee eeeee MeMe8 (888ee, 8.8eeee) eeeeeeeee ee MMM (8eM). Mee eeeeeeeee eeeeeee eee eeeeeee eee 8eee ee 8°M eee eeee eee 8,8-eeeeeee 8,8-eeeeeeee 88 (8.8eeee) ee MMM (8eM) eee eeeee. Meeee eeeeeeee eee 8.888e ee 888°M, eee eeeeeee eee eeeeeee eeee 8M ee MeMMM8 eee eeeeeeeee eeee MeMMe. Mee eeeeeee eeeee eee eeeeeeeeeeee eeeeee eeee 8.8M ee Me8M8M8 eee eee. ee MeMe, eee eeeee (MeMM8). Meeee eeeeeee ee eee eeeeeee ee eeeeeee eeeeeeee, eee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee) ee eeee 88; eeeee: 8888%.

8-(8-Meeee)eeeeeeee (88) eeee 8-Meeee-8-(8-eeeee)eeeeeeee; Meeeeee Meeeeeeee:[‌888‌]

Me e eeee ee 8-eeeee-8-(8-eeeee)eeeeeeee (888ee, 8.888eeee) ee MeMM (88eM) eeeee e M8 eeeeeeeeee eee eeeee eeeeeeeeee (8.8ee, 8.888eeee) eee 88% Me/M (88ee). Mee eeeeeee eee eeeeeee ee ee eee eeeee 8e eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8) ee eeee 88; eeeee: 88ee (88%).

Meeeeee (88); Meeeeee Meeeeeeee:[‌888‌]

M eeeeeee ee eee-8-eeeeeeeeeeee (8.88e, 8.88eeee), Me(MM)8 (8.88e, 8.88eeee), MeMeM8 (8.88e, 88eeee), eee MeMMM8 (8.88e, 88.88eeee) ee MMM (8eM) eee eeeeeeee eee 8.8e. Mee eeeeeee eee eeeeee ee ee, M8M (8.88eM) eee eeeee, eee eee eeeeeee eee eeeeeee eeee eee eeeeeee eeeeeee eeeee eeeeeee eeeeeeee. Meeeeeeeeeee ee eee eeeeeee eeeeeeee 88; eeeee: 8.88e (88%).

References


Cookie-Einstellungen