EnantioselectiveEthylation of Various Aldehydes Catalyzed by Readily Accessible Chiral Diols

Abstract

Four chiral C2 -symmetric diols were synthesized in a straightforward three-step reaction and demonstrated excellent enantioselectivities and good overall yields. Their catalytic activities were examined via the addition of diethylzinc to various aldehydes. The enantioselective addition of diethylzinc to 2-methoxybenzaldehyde gave the corresponding chiral secondary alcohol with high yields (up to 95%) and moderate to good enantiomeric excess (up to 88%). All synthesized ligands were evaluated in the addition of diethylzinc to various aldehydes in the presence of an additional metal such as Ti(IV) complexes. Chirality 28:593-598, 2016. © 2016 Wiley Periodicals, Inc.

Preparation of mesoporous silica and organosilica nanostructures functionalized with C2‐symmetric diol and their catalytic performance in diethylzinc addition to aromatic aldehydes

“…As seen from Table 2, the conversion values were obtained in the range of 82–99% (Table 2, entries 1, 4, 7, and 10). In our previous study, (1 R ,2 R )‐1,2‐bis(4‐bromophenyl)‐ethane‐1,2‐diol was reported as an effective catalyst for the reaction of diethylzinc addition to aldehydes 57 . In that study, that homogenous chiral ligand gave high catalytic activity and high enantioselectivity (90% and 88% ee ) in the reaction of diethylzinc addition to 2‐methoxybenzaldehyde.…”

“…In our previous study, (1R,2R)-1,2-bis(4-bromophenyl)ethane-1,2-diol was reported as an effective catalyst for the reaction of diethylzinc addition to aldehydes. 57 In that study, that homogenous chiral ligand gave high catalytic activity and high enantioselectivity (90% and 88% ee) in the reaction of diethylzinc addition to 2-methoxybenzaldehyde. Compared with the results obtained for this model reaction in the presence heterogenous and homogenous catalysts consisting of (1R,2R)-1,2-bis(4-bromophenyl)-ethane-1,2-diol ligand, the conversion values of heterogenous catalysts C 2 -BSi@SBA-15, C 2 -BSi@MCM-41, and C 2 -BSi-MON-(b) were in between 82% and 88% (Table 1, entries 1, 4, and 10) and very close to the value of 90% obtained in the presence of (1R,2R)-1,2-bis(4-bromophenyl)-ethane-1,2-diol.…”

Synthesis of C2-Symmetric Bisphosphines and Their Application in Enantioselective Transition Metal Catalysis

“…The synthetic routes towards the enantiomerically pure C2symmetric bisphosphine ligands with a dioxolane backbone started with the corresponding bromo-substituted diols 1-3 which were previously described by our group (Scheme 1). [47,48] Chiral bromo-substituted diols are the key structures in our synthesis of bisphosphine ligands 7-12.…”

“…Compounds: (1R,2R)-1,2-bis(2′-bromophenyl)-ethane-1,2-diol 1, (1R,2R)-1,2-bis(3′-bromophenyl)-ethane-1,2-diol 2, (1R,2R)-1,2-bis(4′-bromophenyl)-ethane-1,2-diol 3, (4R,5R)4,5-bis-(2 -bromophenyl)-2,2-dimethyl-1,3-dioxolane 4 and (4R,5R)-4,5-bis-(4 bromophenyl)-2,2-dimethyl-1,3-dioxolane 6 were synthesized according to previously described procedures. [47][48][49][50] Analytical TLC was performed using Macherey-Nagel SIL G-25 UV254 plates. Flash chromatography was carried out with Rocc silica gel (0.040-0.063 mm).…”

Oxidation of benzyl alcohol by novel peripherally and non‐peripherally modular C2‐symmetric diol substituted cobalt (II) phthalocyanines

“…( R , R )‐hydrobenzoin 4 [ 29 ] and its derivatives 1 – 3 , [ 30 ] 3‐nitrophthalonitrile, [ 31 ] 4‐nitrophthalonitrile, [ 32 ] C 2 ‐symmetric diol substituted phthalonitriles 6 , 10 and 8 , 12 , and cobalt (II) phthalocyanines 16, 20 [ 33 ] and 14, 18 [ 34 ] were synthesized according to the published literatures. All reagents and solvents were reagent grade quality and were obtained from commercial suppliers.…”