The present study was prompted by our experimental finding of an accelerating effect by an electron-donating OMe group at the ortho position. 10 Although the effect is subtle 2,3-diethynylanisole is only two times more reactive than 1,2-diethynylbenzene at 170 °C 11 (Table 2, Supporting Information) the direction of the change is unexpected. The accelerating influence of an electron-donor substituent clearly contradicts with the simple premise of the Koga− ...
