Reactions of Complex Ligands Part 84. Chiral Diene-dienophile-functionalzed Aminocarbene Complexes of Molybdenum: Synthesis and Intramolecular Diels-Alder Reaction

Article abstract of DOI:10.1016/S0022-328X(99)00098-4

Chiral at metal carbene complexes (η⁵-C5H5)(CO)(NO)Mo=C[C(CH3)=CH2(NRCH2)(2-CH3O)] 2-4 have been synthesized from (η⁵-C5H5)Mo(CO)2NO via a nucleophilic addition/alkylation/aminolysis sequence. In contrast to 2 (R=H), the N-alkylated analogs 3 and 4 undergo intramolecular Diels-Alder reaction upon warming to give the isoindole derivatives 6 and 7 with moderate diastereoselection. These molybdenum carbenes cyclise more readily than their isolobal analogous methacrylic amides, but they are less reactive than their analogs containing a [η⁵-C5(CH3)H4](CO)2Mn or a (CO)5W fragment. This sequence reflects the increasing electron-withdrawing ability of the metal coligand moiety in the order of the molybdenum < manganese < tungsten coligand fragments.