TY - JOUR AU - Sugiyama, Yu-ki; Kariwa, Takuma; Sakurada, Tetsuya; Okamoto, Sentaro TI - Remarkable Activation of an Alkyne [2+2+2]-Cycloaddition Catalyst, 2-Iminomethylpyridine (dipimp)/CoCl2·6H2O/Zn, by a Phthalate Additive SN - 0936-5214 SN - 1437-2096 PY - 2012 JO - Synlett JF - Synlett LA - EN VL - 23 IS - 17 SP - 2549 EP - 2553 ET - 2012/09/28 DA - 2012/10/12 KW - cycloaddition KW - homogeneous catalysis KW - alkynes KW - esters KW - ligands KW - phthalate KW - catalyst activation AB - A catalyst for alkyne [2+2+2]-cycloaddition reactions, 2-(2,6-diisopropylphenyl)iminomethylpyridine (dipimp)/CoCl2·6H2O/Zn, can be effectively activated by addition of a catalytic amount of dialkyl phthalate to enable reactions that cannot proceed under un­activated conditions. The activation by adding phthalate was ligand- and solvent-dependent, and it was unique to dipimp and N-methyl-2-pyrrolidone (NMP). With use of diphosphine ligand instead of dipimp or with use of tetrahydrofuran (THF) instead of NMP, no activation by a phthalate additive was observed. This simple method of catalyst activation with use of inexpensive, commercially available compounds is highly practical and may find many applications. PB - © Georg Thieme Verlag DO - 10.1055/s-0032-1317318 UR - http://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0032-1317318 ER -