结合富马酸酯和CO配体的环戊二烯钴复合物(见图)有效地催化炔烃,腈和/或烯烃的分子间和分子内[2 + 2 + 2]环加成反应,从而生成苯,吡啶或1,3-环己二烯。与[CpCo(CO)2 ]或[CpCo(C 2 H 4)2 ](Cp = C 5 H 5)等催化剂不同,它们具有空气稳定性,易于处理,与微波条件兼容,并且不一定需要辐射才能活跃。
结合富马酸酯和CO配体的环戊二烯钴复合物(见图)有效地催化炔烃,腈和/或烯烃的分子间和分子内[2 + 2 + 2]环加成反应,从而生成苯,吡啶或1,3-环己二烯。与[CpCo(CO)2 ]或[CpCo(C 2 H 4)2 ](Cp = C 5 H 5)等催化剂不同,它们具有空气稳定性,易于处理,与微波条件兼容,并且不一定需要辐射才能活跃。
see text] A 2-(2,6-diisopropylphenyl)iminomethylpyridine (1a)/CoCl(2).6H(2)O/Zn reagent has been developed as an effective instant catalyst for the intra- and intermolecular cyclotrimerization of alkynes to substituted benzenes, making the method extremely practical since the reagent, 1a/CoCl(2).6H(2)O/Zn, is inexpensive and easy to handle and the reaction is less sensitive to moisture and is reasonably
Disclosed is a process for production of a substituted benzene, which comprises intramolecularly and/or intermolecularly trimerizing a triple bond in an alkyne in the presence of a transition metal catalyst to yield a substituted benzene compound. In the process, the transition metal catalyst is prepared from an iminomethylpyridine represented by the formula (1) or (2), a transition metal salt or a hydrate thereof, and a reducing agent in a reaction system and is used to perform the trimerization. The process can be used in any one of the intramolecular cyclization of a triyne compound, the cyclization of a diyne compound or an alkyne compound and the intermolecular cyclization of three molecules of an alkyne compound, is excellent in economic effectiveness and operability, and is practically advantageous.
wherein R
1
and R
3
independently represent a linear or cyclic C
1
-C
20
aliphatic hydrocarbon group or the like; R
2
represents a hydrogen atom or the like; X represents a hydrogen atom, O or the like; and Y represents O, S or the like.
[reaction: see text] Allyl and propargylethers were effectively deallylated or depropargylated to the parent alcohols via a C-O bond cleavage catalyzed by a low-valent titanium reagent (LVT), Ti(O-i-Pr)4/TMSCl/Mg or Ti(O-i-Pr)4/MgBr2/Mg, under mild reaction conditions. Differentiation between the allyl and propargylethers was achieved by the reaction in the presence of AcOEt as an additive. The reagent
A cobalt carbonyl cluster, methylidynetricobaltnonacarbonyl, catalyzed inter- and intramolecular cyclotrimerization of alkynes producing substituted benzene derivatives in good to excellent yields.
FeCl3 by in situ reduction with zinc powder in the presence of imidazol-2-ylidene or bidentate nitrogen ligand could effectively catalyze intramolecular cycloisomerization of triynes to annulated benzenes. With a 2-iminomethylpyridine ligand, hydrates of FeCl2 and FeCl3 as well as their anhydrous ones could be used.