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Air‐Stable CpCo I –Phosphite–Fumarate Precatalyst in Cyclization Reactions: Comparing Different Methods of Energy Supply
Author(s) -
Fischer Fabian,
Hapke Marko
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201800196
Subject(s) - chemistry , reactivity (psychology) , olefin fiber , reaction conditions , catalysis , microwave irradiation , yield (engineering) , organic chemistry , ethylene , microwave , combinatorial chemistry , photochemistry , medicine , alternative medicine , pathology , materials science , physics , quantum mechanics , metallurgy
The robust Co I precatalyst [CpCo(P{OEt} 3 )( trans ‐MeO 2 CHC=CHCO 2 Me)] was investigated in cyclotrimerizations, furnishing benzenes and pyridines from triynes, diynes and nitriles, comparing the influence of different ways of energy supply; namely, irradiation and conventional (thermal) or microwave heating. The precatalyst was found to work under all conditions, including the possibility to catalyze cyclotrimerizations at room temperature under photochemical conditions at longer reaction times. Performance of the reactions in a microwave reactor proved to be the most time‐efficient way to rapidly assemble the expected reaction products; however, careful selection of reaction conditions can be required. The synthesis of pyridines and isoquinolines successfully involved the utilization of versatile functionalized nitriles, affording structurally interesting reaction products. Comparison with the known and often applied precatalyst CpCo(CO) 2 demonstrated the significantly higher reactivity of the CpCo I –phosphite–olefin precatalyst.