Calcium-mediated Catalytic hydramination and hydrophosphanylation reactions

The hydroamination of diphenylbutadiyne with primary and secondary arylamines requires a reactive catalyst. In the presence of heterobimetallic K2[Ca{N(H)Dipp}4] (Dipp = 2,6 diisopropylphenyl) [2] the performance of this reaction in THF yields [3], [4], [5], [6], [15], [16] and [17] within 3 days at room temperature when derivate arylamines have been used. If the hydroamination reaction of diphenylbutadiyne is performed in refluxing THF for 6 days, N-aryl-2,5-diphenylpyrroles [7], [8], [9], [10], and [11] are obtained regardless of the substitution pattern of the primary arylamines. The hydroamination of diphenylbutadiyne with 1 equiv of the secondary amines HNRR′ (R/R′ = Ph/Ph, Ph/Me, and p-Tol/Me) in the presence of same pre catalyst [2] yields the corresponding 1-(diorganylamino)-1,4-diphenylbut-1-ene-3-ynes [12], [13] and [14] as a mixture of E/Z isomers, these tertiary alkenylamines react with diphenylphosphane to form [18], [19] and [20] in the presence of catalytic amounts of [(thf)4Ca(PPh2)2] or of the same calciate K2[Ca{N(H)Dipp}4] ([2]). Whereas the hydroamination is regio-(amino group in 1-position) but not stereoselective (formation of E and Z isomers), this second hydrofunctionalization step is regio- (phosphanyl group in 4-position) and stereoselective (only E isomers are formed), finally leading to mixtures of (E,E)- and (Z,E)-1-(diorganylamino)-1,4-diphenyl-4-(diphenylphosphanyl)-buta-1,3-dienes.