Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
1.4.1.8.1 Intermolecular [2+2+2] Cyclization of Diynes and Nitriles: Synthesis of Pyridines

DOI: 10.1055/sos-SD-001-00322

Malacria, M.; Aubert, C.; Renaud, J.-L.Science of Synthesis, (20011448.

Several groups independently discovered that cobalt complexes could cocyclize alkynes with nitriles to furnish pyridines 21 (Scheme 11). Wakatsuki and Yamazaki first reported a stoichiometric[‌44‌] and then a catalytic synthesis of pyridines using cobaltacyclopentadienes to promote the reactions.[‌45‌] These reactions took place under relatively mild conditions, even at room temperature. Further developments by Bönnemann established the scope and limitations of the totally intermolecular cycloaddition process.[‌5‌] Later, a more comprehensive and authoritative study of this reaction with full details of the correlations between catalyst and structure/reactivity was published.[‌46‌,‌47‌] It was demonstrated that there were practical improvements in convenience and overall yield through the use of more labile [CoCpL2] sources, while chemoselectivity was maximized by maintaining an excess of nitrile and adding the alkyne in portions. In this way, excellent yields of 2-alkyl- and 2-arylpyridines are synthesized from acetylenes and nitriles, using either cycloocta-1,5-diene(η5-cyclopentadienyl)cobalt(I) (2) as catalyst or cobaltocene[‌48‌] or other more exotic sources of cobalt(I). Yields of pyridines 90% were obtained using this methodology; the reaction required only 23hours at 120130°C and exhibited catalytic turnover numbers of several hundred. Pyridine itself is also accessible from acetylene and hydrogen cyanide.[‌49‌] Applications of this methodology in the synthesis of pyridines containing chiral substituents at C2 have been developed as well.[‌50‌,‌51‌]

Meeeee 88 Meeeee(M)-Meeeeeeee 8-Meeeeeeeeee Meeeeeee Meeeeeeee[‌88‌‌88‌]

Meeeeeeeeee eeeeeee eeeee eeeeeee eeee eeeeeeee ee eee eeeeeeee ee eeeee eeeeeeeee ee eeeeeeee eeeeeeeeeee eeeeeeeee (Meeeee 88). Meeeeeeeeee eeeeeee eeee eeeeeeeeeeeeeeee eeeeeeeee ee eeeeeeeee eeeeee; eeeeeee, eeee eeeeeeeeeeeeeee eee eeeeeeeeeeeee eeeeeeeeeeeee eeeeeee, 8,8,8- eee 8,8,8-eeeeeeeeeeeeee eeeeeeeee 88 eee 88 eee eeeeeee eeeeee ee eeeeeeeeee eeeeeee ee eeee eeeeee (ee. 88%).

Meeeee 88 Meeeee(M)-Meeeeeee Meeeeeee ee Meeeeeeeeee Meeeeeeeee eeee Meeeeeee

Mee 8,8- eee 8,8-eeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeee 88 eee 88 eeee eeeeeeeee eeeeeeeeeee ee eeeee eeeeeeeee (Meeeee 88), eeee eee eeeeee eeeee eee eeeeeeeeeee eeeeeeee eeeeeee (ee eeeeeeee ee eee eeeeeeeeeeeee ee eeeeeee). Meeeeeeee ee eee eeeeeee ee eeeeeeeeeeeeee eee eeeeeee eee eeeeeeeeeeee eeeeeee ee eee eeeeeeeeeeee.[‌88‌] Me ee eeeeeeeee eeeeee ee eeeeeee,[‌88‌,‌88‌] eeeeee(M) eeeeeeeee eeeeeeeeee e eeeeeee ee eeeeeeeeeee eeeeeeeeeeeeeeee eeeeee eeee eeee eeeeeeee ee eeeeeeeeeeeeeee eeeeeee eee ee eee eeeee eeee eeee eeeeeeeee eeeeeeee eee eeeeeeeeeeeeeeee eee eeeeeee ee eeeeeeee eeeeeee ee eee eeeee. Meeeeeee-eeee eeeee eeeeeee, eeee ee eeee ee [Me(M8M8MM8Me)(eee)] (8), eeeeeee eee eeeeeee eeeeeeeeee eee eee eeeeee eeeeeeeeeeeeeeee (ee. 8.8:8).[‌88‌] Meeeeeeeee, eee eeeeeeee-eeee eeeee ee [MeMe*(eee)] ee eeee eeee eeeeeeeee, eeeeee eeeeee eeee e 8.8:8 eeeee ee 8,8,8- ee 8,8,8-eeeeeeeeeeeeee eeeeeeee, eee ee eee eeee ee eeeeeeee eeeeeeeeee eeeeeeeeee.

Meeeee 88 Meeeeeeee ee eee Meeeee-Meeeeeeee Meeeeeee Meeeeeeee[‌88‌,‌88‌]

Meeeeeeeeee eee eeeeeee eeeeeeee eeee eeeeeeeeeeeeee eee eeeeeee.[‌88‌] Meee eeeeeeee ee eeee eeeeeeeeeee eeeeeee eee eeeeeeee eee ee eeeeee eeeeeee eee eeeeeeeeeee eeeeeeeee. Mee eeeeeee, eeeeeeee-8-eeeeeeeeeeee eeeeee eeee eeeeeeeee ee eeeeee eee eeeeeeeee eeeeee 8,8-eeeeeeeee ee 88% eeeee. Meeeeeeeeee eeeeeee eeeeeeeeeeeee ee eee 8-eeeeeeee, ee eeeeeeeee eeeeeeee ee eeeeeee ee eeeeeeeeee eeeeeeeee, eeee eeee eeeeeeee eeee eeeeee eeeeeeee.[‌88‌]

α,ω-Meeeeeeeee ee eee eeeee eeeeeeeeeeeeeeee eeeeeee eeee eeeee eeeee eeeeeeeee eeeeeeeeeee eeeeeeeeeeeeeee eeee eee eeeeeeeee ee eeeeee ee eeeeee ee(8-eeeeeee)eeeeeee.[‌88‌]

Meeeeeeee eeeeeeeeeeeeee eeeeeeeeeeeeee ee eeeeeeee eeee α,ω-eeeeee eee eeee eeeeeeeee eee eee eeeeeeeee ee ee- eee eeeeeeeeee eeeeeeee eeeeeeeeeee (Meeeee 88), eeeeee eee eeeeeee eeeee e eeeeeeee eeeeeeee-eeeeeeeeeee eeeee eeee M8M8 ee MM8Me.[‌88‌] Meeeeee eeeeeeeee ee eeeeee eeeeeeeeeeeeee, ee eeeeeeee eeee eee eeeeeee ee eeeeeeeeeeeeee eeeeeeeee. Meeeeeeeeeee ee eee eeeeeeeee ee eeeeeeeeee (eeeeeee M8) eeee eeee eeeeeeee ee eee eeeeee. Meeeeeeeeee eeeeee eee eeeeeeeeeeee eee eeee ee eee eee eeeeeeeeeee eee eee eeeee eeeeeee ee eeeeee eeeee eee eeeeeeee eeeeeeeee.[‌88‌,‌88‌] Mee eeeeeeeeeeeee ee α,ω-eeeeeeeeeeee eeee eeeeeee ee e eeeeeeeeeeeee eee eeeeeeeee eeeeeeee eee eee eeeeeeeee ee eeeeeeee eeeeeeeee 88 (Meeeee 88).[‌88‌,‌88‌] Meeeeeeeeeeeeeee ee eeeee eeeeeeee ee eee eeee ee eeeeeeeeeeeee eeeeeee eee eeeee ee eeeeeeeee ee eee eeeeeeee eeeeeeeeeeee 88 eeeeee eee eeeeee eeeeeeeeeee eeeeeeee eeee ee eee eeeee. Meee eeee eeeeeeee eee eeeeeeeeee ee eee eee eeee ee e eeeeeeee eeeeeeeee ee eeeeeeee eeee.[‌88‌]

Meeeee 88 Meeeeeeee Meeeeeeeeeeeee Meeeeeeeeee ee Meeeee eeee Meeeeeee eee ee Meeeeee eeee α,ω-Meeeeeeeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeee Meeeeeeee 88; Meeeeee Meeeeeeee:[‌88‌]

M eeeeeeee eeee (eeeee eeeeeeeeeeeeee eeeeee) ee eee α,ω-eeeee (8.8eeee), eee eeeeeee (8.8eeee), eee [MeMe(MM)8] (8; 88μM, 8.8eeee) ee e-eeeeee (88eM) eee eeeee eeee 888e (ee eeeeeee eeee) ee eeeeeeee e-eeeeee (88eM) eee eeeeee ee eeeeee eeeee M8. Meeee eeeeeee ee eee eeeeeee eeeee eeeeeee eeeeeeee, eee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, Me8M) ee eeeeee eee eeeeeeee eeeeeeeee 88.

Meeeeeee Meeeeeeee 88; Meeeeee Meeeeeeee:[‌88‌]

M eeeeeeee eeee (eeeee eeeeeeeeeeeeee eeeeee) ee eee α,ω-eeeeeeeeeee (8 eeeee), eee eeeeee (8.8 eeeee), eee [MeMe(MM)8] (8; 8.8 eeeee) ee e-eeeeee eee eeeee eee e eeeeeee eeee (88e) ee eeeeeeee, eeeeeeeee, eee eeeeeeeeee (eeeeeee eeeee, 888M, eeeee eeeeeeeee eeee) e-eeeeee. Mee eeeeeeee eeee eeeeeeeeeeee eeeeeee eee eee eeeeeeee eeeeeeeee 88 eeee eeeeeeee ee eeeee eeeeeeeeeeeeee ee eeeeee eee.

References


Cookie-Einstellungen