Efficient Asymmetric Simmons-Smith Cyclopropanation and Diethylzinc Addition to Aldehydes Promoted by Enantiomeric Aziridine-Phosphines

Aziridine sulfides and disulfides as catalysts for the enantioselective addition of diethylzinc to aldehydes.

Chiral aziridine sulfides and disulfides were synthesized from readily available and inexpensive R-cysteine by a Mitsunobu reaction; their application in the addition of diethylzinc to aldehydes provides secondary alcohols with up to 99% ee and S-configuration.

Effect of spacers on the activity of soluble polymer supported catalysts for the asymmetric addition of diethylzinc to aldehydes

A chiral Zn(II)–salen complex tethered with poly(ethylene glycol) (PEG) was synthesized. This soluble polymer-supported complex was found to catalyze the asymmetric addition of diethylzinc to a series of aromatic aldehydes in good yields and with good enantiomeric ratio (er). The PEG-supported catalyst could be recycled and reused up to three times. The reactivity and selectivity of the catalys...

Asymmetric Preparation of D-Phg-L-Pro Dipeptide-derived Chiral Ligands for Enantioselective Addition of Diethylzinc to Aldehydes

Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by a Titanate Complex with a Chiral Tetradentate Ligand.

The addition of dialkylzincs to aldehydes is one of the most widely studied carbon-carbon bond-forming reactions. Many systems reported to date use amino alcohols as ligands and zinc complexes as catalysts.1 The asymmetric version of this alkylation reaction can also be catalyzed by chiral titanate complexes2-4 (e.g., TADDOLs2 and chiral sulfonamides3). We have recently studied a titanate compl...

Direct asymmetric catalytic 1,2-addition of RZnX to aldehydes promoted by AlMe3 and reversal of expected stereochemistry.

Addition of AlMe3 to commercial THF solutions of RZnX (R = aryl, functionalised aryl, vinyl; X = Br, I) simultaneously promotes Schlenk equilibria (leading to competent nucleophiles) and the formation of an Al-Zn-ligand catalyst delivering 80-90% ee for Ar(1)CH(OH)Ar(2) formation from aldehydes.