Syntesis and reactions of 3-etynyl-2-(triphenylphosphoimino)-1-azaazulenes

3-(Trimethylsilylethynyl)- and 3-(phenylethynyl)-2-(triphenylphosphoimino)-1-azaazulenes were synthesized by the Appel reaction of the corresponding 2-amino-3-ethynyl-1-azaazulenes. Reaction of 3-(phenylethynyl)-2-(triphenylphosphoimino)-1-azaazulene (8b) with Cu(OTf)2 gave 3-(2-oxophenethyl)-2-(triphenylphosphoimino)-1-azaazulene (11), 3-(1,2-dioxophenethyl)-2-(triphenylphosphoimino)-1-azaazulene (12), and 2-amino-3-(1,2dioxophenethyl)-1-azaazulene (13). The structure of 13 was decided by X-ray structure analysis, and the structure of 12 was discussed by molecular orbital calculation. Reaction of 8b with aryl isocyanate in the presence of benzoyl peroxide gave 1,10-diazabenz[a]azulene derivative.