154975-41-4Relevant academic research and scientific papers
Cobaltocene-induced low-temperature radical coupling reactions in a cobalt-alkyne series
Melikyan, Gagik G.,Rivas, Bianca,Harutyunyan, Stepan,Carlson, Louis,Sepanian, Ruth
, p. 1653 - 1663 (2012/04/23)
A novel method for the low-temperature generation of Co2(CO) 6-complexed propargyl radicals is developed. It consists of an in situ preparation of the respective cationic species (-50 to -10 °C) and their rapid reduction with cobaltocene, Cp2Co, at -50 °C. The optimized experimental protocol is applied to both inter- and intramolecular reactions, affording topologically diverse α-aryl and α-napthyl, d,l- and meso-1,5-hexadiynes and 1,5-cyclodecadiynes. The d,l configuration is the most preferable steric arrangement in intermolecular radical C-C bond-forming reactions (d,l 69-92%), while a reversal of stereoselectivity is observed in intramolecular cyclizations (meso 79%). Under oxidizing conditions (Ce4+), decomplexation affords d,l-3,4-diaryl- and d,l-3,4-(1-/2-naphthyl)-1,5-hexadiynes in good to excellent yields (47-98%). An enhanced functional tolerance is showcased by introducing peripheral acid-sensitive functionalities, such as benzyloxy and methylenedioxy groups, and carrying out a five-step conversion scheme-from commercial aromatic aldehydes to radical dimers-under nonacidic conditions.
Cobalt-complexed propargyl cations: Generation under neutral conditions and spontaneous, high-temperature conversion to propargyl Radicals
Melikyan, Gagik G.,Sepanian, Ruth,Spencer, Ryan,Rowe, Aaron,Toure, Pogban
, p. 5541 - 5549 (2010/01/06)
A novel method for the generation of Co2(CO)6- complexed propargyl cations under neutral conditions is developed. The optimized experimental protocol involves treatment of the respective Co 2(CO)6-complexed prop
Tetrahydrofuran as an one-electron donor: Highly diastereoselective coupling of cobalt-complexed propargyl alcohol
Melikyan, Gagik G.,Deravakian, Asatour
, p. 143 - 145 (2007/10/03)
A novel one-step reductive dimerization of Co-complexed propargyl alcohol 5 has been developed producing dl- and meso-(3,4-diphenyl-1,5-hexadiyne)-bis-dicobalt hexacarbonyl (8,9) with unprecedented diastereoselectivity of 90%. A tandem action of a variety of one-electron/hydride ion donors and Broensted Lewis acids has been tested both in one- and two-step methods with the latter including the isolation of propargyl cation 1.
