Mukaiyama-Michael aldol reaction

Scheme 2.7. Domino Mukaiyama/Michael/aldol reactions catalyzed by Sml2(THF)2.

Scheme 8. Enantioselective Mukaiyama-Michael aldol reaction catalyzed by dioxaborolidine.

Lewis Acid Catalyzed Reactions. S amarium iodide catalyzes several transformations by presumably acting as a Lewis acid. For example, it is an efficient catalyst for the imino-Diels-Alder (eq 70) and for imino-aldol reactions. Tandem Mukaiyama-Michael-aldol (eq 71) and Michael imino-aldol processes have also been reported. ... 

Kitazume and coworkers used microreactors with microchaimels 100 pm wide and 40 pm deep for the synthesis of a series of organofluorine compounds [19,20]. The silylation of4,4,4-trifluorobutan-2-one and the Mukaiyama-type aldol reaction of the resulting enol silyl ether with acetals gave good yields of the desired products [20]. They also described nitro-aldol reactions of 2,2-difluoro-l-ethoxyethanol and Michael additions of nitroalkanes to ethyl 4,4,4-trifluorocrotonate and ethyl 4,4-difluorocrotonate [19,20]. Reactions were carried out at room temperature, and... 

Using a cyclic enone 2-29b and an ester-TMS enolate 2-30 in the presence of catalytic amounts of SmI2(THF)2, the Michael addition and the Mukaiyama/aldol reaction with the added aldehyde 2-32 led to the diastereomeric adducts 2-33 and 2-34 via 2-31 with a dr =80 20 to 98 2 and 70-77% yield (Scheme 2.7) [13]. The major product is the trans-l,2-disubstituted cycloalkanone. 

Under classical Mukaiyama conditions, silyl enol ether 2-372 and the Michael acceptors 2-373 and 2-374 underwent a twofold 1,4-addition to form an enolate in which an ideal set-up exists for an intramolecular aldol reaction. This led to 2-375 with the desired structural core of 2-376 in an overall yield of 42%. 

Many examples of asymmetric reactions catalyzed by copper complexes with chiral ligand systems have been reported. In particular, various copper-bis(oxazoline) catalysts (e.g., complexes (H) to (L), Scheme 48) are effective for carbon-carbon bond-forming reactions such as aldol,204 Mukaiyama-Michael, Diels-Alder,206 hetero Diels-Alder,207,208 dipolar cycloaddition,209,210... 

Intermolecular Michael addition [4.1] Intermolecular aldol reaction [6.2.1] Intramolecular aldol reaction [6.2.2] Aldol-related reactions (e.g. vinylogous Mukaiyama-type aldol) [6.2.3]... 

The third part of this chapter reviews previously described catalytic asymmetric reactions that can be promoted by chiral lanthanoid complexes. Transformations such as Diels-Alder reactions, Mukaiyama aldol reactions, several types of reductions, Michael addition reactions, hydrosilylations, and hydroaminations proceed under asymmetric catalysis in the presence of chiral lanthanoid complexes. 

Miscellaneous. There are several other reports on the application of this ligand to catalytic asymmetric reactions, although enantioselectivities are modest. Those reports include the Mukaiyama-Michael reaction, allylation of aldehydes, asymmetric Diels-Alder reaction, Mukaiyama-Aldol reaction of ketomalonate, aziridination reaction of a-imino esters, and asymmetric hetero-Diels-Alder reaction. ... 

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