Manganese and cobalt 3-oxobutylideneaminato complexes: Design and application for enantioselective reactions

Abstract

The optically active 3-oxobutylideneaminato transition-metal complexes have been developed as efficient catalysts for a variety of enantioselective reactions; e.g. the corresponding manganese(III) complexes catalyzed the enantioselective aerobic epoxidation of unfunctionalized olefins, and the corresponding cobalt complexes have been developed for the enantioselective borohydride reduction of various carbonyl compounds. The cobalt complexes could also be employed for the catalytic enantioselective cyclopropanation with diazoacetates and the Lewis acid catalyses such as the hetero Diels-Alder reaction, carbonyl-ene reaction, and 1,3-dipolar cycloaddition of nitrones. In the presence of the cobalt complex, the Henry reaction proceeded with a high enantioselectivity, and the enantioselective chemical fixation of carbon dioxide to obtain the optically active cyclic carbonate. In these Lewis acid catalyses, the valence of cobalt and the counter anion have significant effects on the reaction rate and stereoselectivity. q

Cyclopropanation Reactions Mediated by Group 9 Metal Porphyrin Complexes

“…[57] Yamada et al developed a catalytic system based on chiral ketoiminatocobalt(II) complexes to attain very good diastereo-and enantiomeric excesses. [58] The nature of the cobalt ligand promoted a trans selectivity; the cyclopropanation of styrene by EDA yielded 90 % of the corresponding trans-cyclopropane with 96 % ee. [59] The effect of the addition of a coordinating ligand, such as N-methylimidazole (NMI), to enhance the stereocontrol of cyclopropanation reactions was also investigated.…”

Cobalt‐Mediated Carbene Transfer Reactions

“…Among a series of N-heterocycles tested, addition of N-methylimidazole (NMI) resulted in significant improvement of asymmetric olefin cyclopropanation with tert-butyl diazoacetate (2a) amine bridge while replacing the ketone substituents of K1 with bulky ester groups (Scheme 15.4). [8,15] The complexes [Co(K2)] and [Co(K3)] proved to be highly selective catalysts for the reaction, generating trans-cyclopropane 15 with stereocontrol of up to 91:9 diastereomeric ratio and 99% ee (Scheme 15.4).…”

“…6a,b In the presence of carbon monoxide, [Co 2 (CO) 8 Due to the high reactivity of ketenes, in situ formed 47 was directly converted into malonic acid derivatives 49-51 in the presence of alcohol, phenol, amine, or diazoacetate derivatives (Scheme 15.15). 6f,g When N-tert-butylbenzylimine was added, direct reaction with ketene 47 resulted in cyclization to produce β-lactam 52 in 95% yield.…”

“…For example, Carreira and coworkers reported that chiral [Co(Salen)] complexes could catalyze the decomposition of trifluoromethyl diazomethane (6) for asymmetric olefin cyclopropanation, resulting in the forma tion of enantiomerically enriched trifluoromethylcyclopropanes (8) (Scheme 15.1). 10 Chiral [Co(Por)] complexes were shown by Zhang and coworkers for the first time to be effective catalysts to decompose sulfonyldiazomethanes (7) for asymmetric synthesis of cyclopropyl sulfones (8) from olefins (1) with both excellent diastereoselectivity and enantioselectivity (Scheme 15.1). 11 Diazo compounds bearing two electron-withdrawing groups, namely acceptor/acceptor-substituted diazo reagents, typically display both low reactivity and poor stereocontrol in transition metal-catalyzed carbene transfer reactions.…”

Synthesis, Physical Characterization of M(III) Transition Metal Complexes Derived from Thiodihydrazide and 5‐tert‐Butyl‐2‐hydroxy‐3‐(3‐phenylpent‐3‐yl) Benzaldehyde

“…Moreover, Schiff base are regarded as privileged ligand [24]. Due to their capability to form complexes with different transition metals can act as catalysts for many different reactions [25][26][27][28][29]. The cross linking agents can also be derived from metal complexes with O−N− or -S ligands for example, the intra-coordination salt such as salicylates, anthraanilates and aliphatic or aromatic amines can form strong five of six membered chelates rings which are able to produce the metal containing cross linking agents with required properties [30].…”