[4 + 2] Benzannulation of Enynes with Alkynes

A Cascade Sonogashira Cross‐Coupling‐Substitution‐Elimination Reaction for the Synthesis of Linear Conjugated Dienynes

“… [7] Besides, enynes are also useful intermediates to prepare aromatic rings, heterocycles, allenes, and related structures. [ 8 , 9 ] The versatility of 1,3‐enynes allows to prepare propargyl cyclopropanes, [10] allenes,[ 11 , 12 ] and to perform [2+2] cycloadditions. [13] …”

Tandem [4 + 2]/[2 + 2] cycloaddition of o-carboryne with enynes: facile construction of carborane-fused tricyclics

“… 5 Strained six-membered-ring allenes are also found as common intermediates in the [4 + 2] cycloaddition of conjugated enynes with unsaturated molecules, including alkenes and alkynes. 6,7 Aryne, a very reactive archetypal two-electron component in [4 + 2] cycloadditions, can react with conjugated enynes to generate isoaromatic cyclic allenes, which undergo isoaromatization to afford the polycyclic aromatics ( Scheme 1b ). 8 …”

Cobalt-Catalyzed Cross-Benzannulation of Conjugated Enynes and Diynes

“…Two transition metal-catalyzed benzannulation reactions of enynes and diynes have been reported thus far: first, the palladium-catalyzed homobenzannulation of two conjugated enynes 1 to symmetric styrenes 2 as well as the cross-benzannulation of enynes 1 and diynes 4 reported by Yamamoto and Gevorgyan; second, the regiodivergent cobalt-catalyzed homobenzannulation of enynes 1 recently reported by our group . In the cobalt-catalyzed reaction, the regioselectivity is strongly solvent-dependent leading to regioisomer 3 , which is not accessible via the palladium-catalyzed reaction.…”