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43.8.2.3.2 Method 2: Alk-1-ynes by Base-Catalyzed Rearrangement of Internal Alkynes

DOI: 10.1055/sos-SD-043-00415

Krueger, A.Science of Synthesis, (200843503.

The contrathermodynamic formation of alk-1-ynes can also be achieved. In these cases, the formation of the product acetylide, e.g. by reaction with alkali metals or alkali amides (preferably the soluble potassium amide) shifts the equilibrium from 102 to a high concentration of the salt of the terminal alkyne 103.[‌148‌] Subsequent hydrolysis gives the terminal alkyne in high yield. The triple bond can not only migrate from the 2-position but over several CC bonds, especially when strong bases such as potassium 3-aminopropylamide (KAPA) are used. This reaction is often called the acetylene zipper reaction (Scheme 46 and Table 6).[‌162‌,‌163‌] Branching in the side chain completely stops the migration. The isomerization proceeds exclusively to the free end, yielding one single isomer.[‌162‌]

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Meeeeeeeeee 88

e e Meeeeee Meeee (%) Mee
8 8 eee-8-eee 88e [‌888‌]
8 8 eee-8-eee 88e [‌888‌]
8 8 eee-8-eee 88e [‌888‌]
8 8 eeeeeeee-8-eee 88 [‌888‌]

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Meeeeeee Meeeeeee Meeeeee Meeeeeeeeee Meeee (%) Mee
8-eeeeeeeee-8-eee 8-eeeeeeeee-8-eee MMMM (8.88.8 eeeee), eeeeeee-8,8-eeeeeee, 88°M, 888eee eeeeee [‌888‌]
8-eeeeeeeee-8-eee 8-eeeeeeeee-8-eee MMMM (8.88.8 eeeee), eeeeeee-8,8-eeeeeee, 88°M, 888eee 88e [‌888‌]
8,8-eeeeeeeeeee-8-eee 8,8-eeeeeeeeeee-8-eee MMMM (8.88.8 eeeee), eeeeeee-8,8-eeeeeee, 88°M, 888eee 88e [‌888‌]
8-eeeeeeeeee-8-eee 8-eeeeeeeeee-8-eee MeMe, Me8M, 8°M ee ee, 88e 88 [‌888‌]

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Mee eeeeeeee ee eee eeeeeee ee eeee eeeeeeeeeeee; eeeeeeeeeeeeee eeeeeeeeeee eee eeeeeeeee ee eeee. M eeeeeeeee eeeeeee ee eee eeeeeeeeeeeee ee eeeeeee eeeeeeee 888 ee eee-(ω8)-ee-8-eee 888 ee eeeeeeeee eeee eeeeeeeee 8-eeeeeeeeeeeeeeee (MMMM) ee eeeeeee-8,8-eeeeeee (Meeeee 88).[‌888‌,‌888‌] Me eeeee eeeee eeee, eeeeeeeee eeeeeee eeeeeee eeeeeeeee ee eee eeeeee eeee eee eee eeeeeeeee ee eeeeeeeee eeeeeee ee eeeeeee ee eee eeee ee eeee eee eeeeeeeeee eeee eeeee.[‌888‌]

Meeeee 88 Mee Meee-Meeeeeeee Meeeeeeee ee Mee-(ω8)-ee-8-eee[‌888‌,‌888‌]

Meeeeeeeeee 88

e e M8 M8 Meeeeee Meeeeeeeee Meeeee (%) Mee
8 8 M M eee-8-ee-8-ee 88°M, 88eee 88 [‌888‌]
8 8 M M eee-8-ee-8-ee 88°M, 88eee 88 [‌888‌]
8 8 M M eee-8-ee-8-ee 88°M, 88eee 88 [‌888‌]
8e 8 M M eeeeeee-88-ee-8-ee 88°M, 88eee 88e [‌888‌]
8 8 Me M eee-8-ee-8-ee 8°M, 88eee 88 [‌888‌]
8 8 Me M eee-8-ee-8-ee 8°M, 88eee 88 [‌888‌]
8 8 Me Me 8-eeeeeeeee-8-ee-8-ee 8°M, 88eee 88 [‌888‌]
8 8 M M eeeee-88-ee-8-ee 8°M ee ee, 8e, eeee 8888°M, 8.8e 88e [‌888‌]
8 8 M M eeeee-88-ee-8-ee 88°M, 88e 88e [‌888‌]
8 8 M M eeeee-88-ee-8-ee 88°M, 88e 88 [‌888‌]

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Meeeee 88 Meee-Meeeeeeee Meeeeeeeeeeee ee Meeeee Meeeeeeeeee Meeeee ee Meeeeeee Meeeeee[‌888‌]

Me eeeeee ee eeeeeeeeeeee eee eeee ee eeee eee eee eeeeeeeee ee eeeeeeee eeeeeee eeee eeeeeeeeeeeeee eee-8-eeee. Mee eeeeeee ee eee eeeeeeeeeeeee ee eee-8-eee 888 ee 8-(8-eeeeeeeeeeeee)eeee-8-eee (888) (Meeeee 88).[‌888‌]

Meeeee 88 Meeeeeeee ee 8-(8-Meeeeeeeeeeee)eeee-8-eee ee Meee-Meeeeeeee Meeeeeeeeeeee[‌888‌]

Meeee eeeeeeeeeeeee, e.e. eeeee-8-ee eeeeee, eee eeee eeeeeeeee ee eeeee-8-ee eeeeee eeeee eeeeee eeeee ee eeeeee eeeeeee, ee eeee eeeeee.[‌888‌] Meeee eeeeeeeee eeee-eeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeee ee eeeeeeee eeeeeeeee, eee eeeeee eeee eeeeeeee eeeeeee eeee eeee eee eeeeee eeeee.[‌888‌,‌888‌]

Me eee eeee ee eeeeeeeeee 888, eeeeeeeeeeeee eeeeee eee eeeeeeeeeee eeeeeee 888 ee eeeeeeeee eeee eeeeeeeee eeeee ee eeeeee eeeeeee; eee M/M eeeee ee eeeee 88:8 (Meeeee 88).[‌888‌]

Meeeee 88 Meee-Meeeeeeee Meeeeeeeeeeee ee Meeeeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeee Meeeeee 888; Meeeeee Meeeeeeee:[‌888‌]

Me e eeeeeeeeee eeeeeee 8.8M eeee ee eeeeeeeee 8-eeeeeeeeeeeeeeee (MMMM) ee eeeeeee-8,8-eeeeeee (88eM, 88eeee) eee eeeeeeee eeeeee 888 (88eeee) eee eeeee eeeee eeeeeee (8888°M). Mee eeeeeee eeeeee eeee eee eee eeeeeeeee eeeeeeeee eeeeeeeeeeee eeeeee eeeeeeeeeee. Meeee 888eee, eee eeeeeee eee eeeeeeee eeee M8M (88eM) eee eeeeeeeee eeee eeeeeee. Mee eeeeeee eeeee eee eeeeee eeee 88% MMe eee eeee eeeee (MeMM8). Meeee eeeeeee eeeeeee ee eeeeeee eeeeeeee eee eeeeeeee eeeeee eee eeeeeeee; eeeee: 88888%.

Meeeeee-88-ee-8-ee (888, M8=M8=M; e=8; e=8); Meeeeee Meeeeeeee:[‌888‌]

Meeeeee-8-ee-8-ee (888, M8=M8=M; e=8; e=8; 8.88e, 88eeee) eee eeeee eeeee eeeee ee e 8.88M eeee ee eeeeeeeee 8-eeeeeeeeeeeeeeee ee eeeeeee-8,8-eeeeeee (88eM, 88eeee).[‌888‌] Meeee eeeeeeee eee 88eee, M8M (88eM) eee eeeee eeeee eee eeeeeee eee eee eeeeeee eee eeeeeee eeeeeee. Meeee eeeeeeeeee, eeeeeee eeeeeee ee eeeeeee eeeeeeee, eee eeeeeeeeeee, eee eeeeeee eee eeeeeeee ee e eeee, eeeee eeeee; eeeee: 8.88e (88%); ee 8888°M.

M,M-Meeeeeeeeee-8-ee-8-ee-8-eeeee (888, M8=Me); Meeeeee Meeeeeeee:[‌888‌]

Mee eeeeeeeee 888 (M8=Me; 88.8e, 8.88eee) eee eeeee ee e eeeeeeeeee eeeeeee eeee ee MMM8 (88e, 8.8eee) ee eee MM8 (888eM). Meeee eeeeeeee eee 8e, eeeee MM8Me (88e, 8.8eee) eee eeeee. Mee MM8 eee eeeeeee ee eeeeeeeee ee 88°M (eeeee eeee). Meeee eeeeeeeeee eee eeeeeee eeeeeee eeeee eeee Me8M, eee eeeeeeee eeeeeee eeeeee eeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeeeeeeeeee eeeeeee e eeeee eeeeee; eeeee: 88.8e (88%); ee 88°M/88Meee; eM88 8.8888.

References