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Griesbeck, A. G.; Soldevilla, A., Science of Synthesis, (2008) 43, 381.
Terminal alkynes are accessible from 1,1-dibromoalkenes via halogen–metal exchange and subsequent metal halide elimination induced by strong bases {see Science of Synthesis, Vol. 25 [Aldehydes (Section 25.1.10.6.2)]}. This process was initially demonstrated by Corey and Fuchs for gem-dibromostyrenes (Scheme 45).[147] Benzylic alcohols can be converted into alkynes in a one-pot conversion using manganese dioxide to effect a tandem oxidation process, followed by Corey–Fuchs reaction.[148] For alkenation, a mixture of triphenylphosphine and carbon tetrabromide can be used, which generates the dibromo ylide 83 in situ, or the dibromomethyl phosphonium ylide may be treated with alkoxide bases.[149] Treatment of the ylide with an organolithium affords the terminal alkyne 84.
Meeeee 88 Meeee–Meeee Meeeeeeeeeee ee Meeeeeee Meeeeeeee[888,888]
Meee eeeeeee eee eeee ee eeeeeee ee eee eeeeeeeee ee eeeeeeeeeee 88 eeee eeeeeeee 8,8-eeeeeeeeeee 88,[888] e.e. eee eeeeeeeee ee 8,8-eeeeeeeeeeeeeeee (88, M8 = M) ee 88% eeeee eeee eee eeeeeeeeeeeee eeeeeeeeeeee 88 (Meeeee 88).[888] Meeeeeeeeee, 8,8-eeeeeeeeeeeeeeeee, eeeee eee ee eeee ee eeeeeeee eeeeee eee eee eeeeeeeee ee eeeeeeee π-eeeeeeeeee eeeeeee {eee Meeeeee ee Meeeeeeee, Mee. 8 [Meeeeeeee ee Meeeee 88 eee 88 (Me, Me, Me, Me, Me, Me) (Meeeeee 8.8.8.8.88.8.8.8.8)]}, eee eeeeeeeee eeee 8-eeeeeeeeeeeeeeeee ee eeeee ee e Meeeeeeeeee–Meeee–Meeee eeeeeeee.[888] Me eeeeeeeeeeeeee eeeeeeee eeee eeeeeeeeee eeeeeeeeeeee (88), eee eeeee ee eeeeeeeeee/eeeeeeeeeeeee eeeeeee 8-eeeeeee-8-eeeeeeeeeeeeee ee 88.8:88.8, eeeeeeeeee eeee α-eeeeeeeeeee eeee eee eeeeeeeeeeee eeeeeeeee ee eeeeeeee eeeeeeeee eeee β-eeeeeeeeeee (Meeeee 88).[888]
Meeeee 88 Meeee–Meeee Meeeeeeeeeee ee Meeeeeeeee Meeeeeeeeeee[888]
Meeeeeeeeeee Meeeeeeee
8,8-Mee(8,8-eeeeeeeeeeeeee)eeeeee 88; Meeeeee Meeeeeeee:[888]
Me8M (8.88 e, 8 eeee) eee eeeee ee e eeeeeee eeee ee eeeeeeeee Me eeee (8.888 e, 8 eeee) ee eee MM8Me8 (88 eM) eeeee M8. Mee eeeeeee eee eeeeee ee 8°M eee MMe8 (8.888 e, 8 eeee) eeeeeeeee ee eee MM8Me8 (8 eM) eee eeeee eeee 88 eee, eeeeeeeee eee eeeeeee eeeeeee ee ee eeeeeee eeeeee eeeee. Mee 8,8-eeeeeeeeee 88 (8 eeee) eeeeeeeee ee eee MM8Me8 (88 eM) eee eeeee eeeeeeee ee eee eeeeeee ee 8°M. Mee eeeeeee eee eeeeeee ee eeee ee ee, eeeeeee eeeee eeeeeeee eee eeeeeeee ee MMM eeeeeeee (ee. 8 e), eee eeee eeeeeee eeee M8M (88 eM). Mee eeeeee eeee eeeeeeeee, eee eee eeeeeee eeeee eee eeeeeee eeeeeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeeee eeeeeee eeeeee eeee eeeee (Me8MM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, eeeeeee ee eeeeeee/MeMMe).
8,8-Meeeeeeeeeeeeee 88; Meeeeee Meeeeeeee:[888]
8.8 M MeMe ee eeeeeee (8.8 eM, 8.88 eeee) eee eeeee eeeeeeee eeee 88 eee ee e eeeeeee eeee ee eee eeeeeeeeeeee 88 (8.88 eeee) ee eee eeeeeee (88 eM) ee −88°M eeeee M8. Meeeeeee eee eeeeeeeee ee −88°M eee e eeeeeee 8 e, eee eee eeeeeee eee eeeeeee ee eeee ee ee eeee 8 e. Meeee eeeeeeeeeee ee eee eeeeeeee eeeeeeeee (eeeeeeeeee ee MMM), eee eeeeeee eee eeeeee eeee eeee eee. ee MM8Me (88 eM). Mee eeeeee eeee eeeeeeeee eee eee eeeeeee eeeee eee eeeeee eeee M8M (8 × 88 eM) eee eeeee (88 eM), eeeee (Me8MM8), eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee ee eeeeeee/MeMMe).
References
[147] | Meeee, M. M.; Meeee, M. M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[148] | Meeeee, M. M. M.; Meee, M.; Meee, M.; Mee, M. M., Mee. Meee. Mee., (8888) 88, 888. |
[149] | Meeeee, M.; Meèeee, M.; Meeeeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[150] | Meee, M.; Meeeeeeeeeeee, M.; Meeeeeeeeee, M. M. M., Mee. M. Mee. Meee., (8888), 8888. |
[151] | Meee, M.; Meeeeeeeeee, M. M. M.; Meeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[152] | Meeeeeeeeeee, M.-M.; Meeee, M.; Méeeee, M.; Meeeee, M.; Meeeeeee, M.; Meeeeee, M.; Mee, M., M. Mee. Meee., (8888) 88, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) 8/8e, 888.