Regioselective solvent-dependent benzannulation of conjugated enynes
作者:Florian Pünner、Gerhard Hilt
DOI:10.1039/c2cc30777d
日期:——
transformation of enynes under cobalt-catalysis leads to symmetrical benzannulation products in dichloromethane. In tetrahydrofuran the cobalt-catalysed reactions afforded the unprecedented unsymmetrical benzannulation products in moderate to good yields and good regioselectivities. In addition, cyclotrimerisation of the alkyne subunit can be realised when electron-deficient enynes are applied in the
The cobalt-catalysed benzannulation of 2-pyridine-substituted enynes gave 2,3-bis(2-pyridyl)styrenes in moderate yields. The reaction with dibromomethane as well as diiodomethane generated the corresponding planar-chiral bispyridinium salts in good yields. On the other hand, the transformations with reagents of the type RCHBr2 to afford diastereomeric products led to the desired conversion. However