2-Aminocyclonona-1,8-dienyl carbene complexes 3a-d are generated by addition of cycloheptenylamines 2a-d to (1-alkynyl)carbene complexes (CO) 5 M=C(OEt)C≡CPh 1a,b (M = W, Cr) in pentane. Compounds 3 are stable in solid state but in solution undergo ring contraction of the nine-membered ring to give (2-aminocycloheptenyl)alkenyl carbene complexes 4a-d which subsequently are transformed into tetrahydroazulenes 5 by elimination of the metal unit. The reaction of 3-aminocyclohexenones 6 with the tungsten compound 1a leads to generation of cyclooctadienon-1-yl carbene complexes 7, from which 5-amino-7,8-dihydrochromylidene complexes 8 are obtained (instead of cyclopentadienes). These transformations rest on a hitherto unknown rearrangement of a (1,3-butadien-2-yl)carbene-into a (1,3-butadien-1-yl)carbene complex.(1-Alkynyl)carbene complexes (CO) 5 M=C(OEt)C≡CPh 1a,b (M = W, Cr) have been applied as stochiometric reagents in a number of highyield transformations which are potentially useful in organic synthesis. 2 For example, it has been shown recently that cyclopentadienes can be generated in [3+2] fashion by reaction of compounds 1 with cyclic tertiary enamines in solvents like dichloromethane. 3c,g (Conjugated) 1-metalla-1,3,5-hexatrienes (CO) 5 M=CC=CC=C [= (1,3-butadien-1-yl)carbene complexes] were found to be key-intermediates in these transformations. 3 In subsequent studies on reactions of compounds 1 with open-chain tertiary enamines and enaminones, respectively, crossconjugated metallatrienes (CO) 5 M=CC(=C)C=C [= (1,3-butadien-2-yl)carbene complexes] were generated instead of conjugated metallatrienes, if the reactions were carried out in pentane. 4 We now wish to report on reactions of compounds 1 with cyclic enamines, in which conjugated as well as cross-conjugated metallatrienes are obtained depending on the reaction conditions. We found that crossconjugated metallatrienes 3 and 7, respectively, are isolated in high yields from reactions of compounds 1 with cyclic enamines 2 and cyclic enaminones 6, respectively, if these reactions are carried out in solvents, like pentane, in which these compounds are sparsely soluble and are therefore precipitated from the reaction mixture. Interestingly, if compounds 3 and 7 are kept in solution they are transformed into conjugated metallatrienes, from which cyclopentadienes 5 and chromenylidene complexes 8, respectively, are finally obtained. Based on the unanticipated fact that a cross-conjugated metallatriene can be converted into a conjugate metallatriene, now light is shed on quite a number of potential applications of cross-conjugated metallatrienes in transformations related to the formation of cyclopentadienes 5 from compounds 3 (Scheme 1).Reaction of a (1-alkynyl)carbene complex 1a,b with a 1-aminocycloheptene 2a-d in pentane leads to precipitation of yellow cyclonona-1,8-dien-1-yl carbene complexes 3 in good yields (Scheme 1). 5 Compounds 3 are stable in solid state, but in solution they readily form compounds 4 by a hitherto unknown rearrangement of a cro...
