Arylation of Aldehyde Homoenolates with Aryl Bromides

Abstract

A mild palladium catalyzed coupling of reactive aldehyde homoenolates with aryl bromides is described. Aldehyde homoenolates are generated by ring opening of cyclopropanols via a C-C cleavage step. The coupling generates aldehyde products at room temperature in 59-93% yield.

Recent Progress in Organocatalytic Asymmetric Domino Transformations

“…Under the catalysis of hydroquinine-derived amide 454,t he initial aza-Henry reaction between 345 and 451 provided 452 as am ixture of trans-452 (major) and cis-452 (minor) isomers.I nt he second step only trans-452 underwent subsequent cyclization to form trans-453 as as ingle diastereomer with high enantioselectivity,w hereast he unreactive cis-452 was gradually converted back to trans-452 via ar etro-aza-Henry/aza-Henry sequence (Scheme 115). [175]…”

Bifunctional Thio/Squaramide Catalyzed Stereoselective Michael Additions of Aldehydes to Nitroalkenes towards Synthesis of Chiral Pyrrolidines

“…The yield of adduct 8 ag decreased to 32% when the reaction proceeded without any acid additive. Diastereo-as well as enantioselectivity, were virtually unchanged ( Table 2, entries [8][9][10][11]. The yield of adduct 8 ag decreased even further to 27% when we used catalyst C7 under classical condition (stirring at r.t. for 48 h).…”

“…Highly functionalized pyrrolidine analogs with three stereogenic centers were synthesized in good yields, as single diastereomers, with high ee by a cinchona alkaloid catalyzed aza-Henry reaction/aza-Michael cyclization. [9] Asymmetric 1,3-dipolar cycloaddition reaction of azomethine ylides with alkenes catalyzed by zinc(II) bisoxazolines provided tetrasubstituted chiral pyrrolidines. [10] Highly functionalized pyrrolidine derivatives with three contiguous stereogenic centers and bearing a trifluoromethyl group have been synthesized with high yields and stereoselectivities through an organocatalytic one-pot domino Michael/Mannich [3 + 2] cycloaddition sequence using a commercially available secondary amine as the catalyst, [11] Brønsted acid-catalyzed three-component asymmetric 1,3-dipolar cycloaddition between aldehydes, amino esters, and dipolarophiles furnished multiply substituted pyrrolidines.…”

Selective Carbon–Carbon Bond Cleavage for the Stereoselective Synthesis of Acyclic Systems

“…[57] A cyclopropanol could also be directly treated with a palladium catalyst in the presence of an aryl halide to afford the b-arylated aldehyde 50 in 75 % yield and with the same enantiomeric ratio as that of the starting cyclopropanol 49 through a direct homoenolate arylation reaction (Scheme 19). [58] When this palladium catalysis is combined with Et 2 Zn, an acylation reaction to give functionalized 1,4-diketones 51 is possible (Scheme 19). [59] Doubly activated cyclopropanes, such as 1,1-cyclopropane diester derivatives, have also been studied extensively owing to their ability to react with different nucleophiles.…”