Pauson-khand carbonylative cocyclizations of acetylenes with cyclopropylallenes

M Ahmar, M Knoke, A de Meijere, B Cazes

Index: Ahmar, Mohammed; Knoke, Mario; De Meijere, Armin; Cazes, Bernard Synthesis, 2007 , # 3 p. 442 - 446

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Abstract

A preliminary experiment was carried out with the hexacarbonyldicobalt complex of 3-hexyne 1a-[Co] and 1,3-dicyclopropylpropa-1,2-diene [6a; R 3 = cyclopropyl (Cpr)] under our original conditions at 0-20 °C in the presence of six equivalents of NMO. [5a] The expected cyclopentenone 7aa was obtained in a low yield of 27%, but with a high 96:4 E/Z stereoselectivity (Table [1] , entry 1). Further trials showed that the efficiency of the cycloaddition depended on the ...