Reactions of complex ligands Part 84. Chiral diene-dienophile-functionalized aminocarbene complexes of molybdenum: synthesis and intramolecular Diels-Alder reaction

摘要

Chiral at metal carbene complexes (#eta#~5-C_5H_5)(CO)(NO)Mo=C[C(CH_3)=CH_2(NRCH_2)(2-C_4H_3O)] 2-4 have been synthesized from (#eta#~5-C_5H_5)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 cyclize more readily than their isolobal analogous methacrylic amides, but they are less reactive than their analogs containing a [#eta#~5-C_5(CH_3)H_4](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.