Search results for "Diethylzinc"
showing 7 items of 17 documents
Stereoselective synthesis and application of tridentate aminodiols derived from (+)-pulegone
2016
Abstract A library of tridentate aminodiols, derived from naturally occurring (R)-(+)-pulegone, was synthesized and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The reduction of pulegone furnished pulegol, which was transformed into allylic trichloroacetamide via Overman rearrangement of the corresponding trichloroacetimidate. The protected enamine was subjected to dihydroxylation with OsO4/NMO system resulting in a 1:1 mixture of (1R,2R,4R)- and (1S,2S,4R)-aminodiol diastereomers. After the removal of the trichloroacetyl protecting groups, the obtained primary aminodiols were transformed into secondary ones. The regioselectivity of the ring closure of the N-b…
Hydrogen and Deuterium Incorporation in ZnO Films Grown by Atomic Layer Deposition
2021
Zinc oxide (ZnO) thin films were grown by atomic layer deposition using diethylzinc (DEZ) and water. In addition to depositions with normal water, heavy water (2H2O) was used in order to study the reaction mechanisms and the hydrogen incorporation at different deposition temperatures from 30 to 200 °C. The total hydrogen concentration in the films was found to increase as the deposition temperature decreased. When the deposition temperature decreased close to room temperature, the main source of impurity in hydrogen changed from 1H to 2H. A sufficiently long purging time changed the main hydrogen isotope incorporated in the film back to 1H. A multiple short pulse scheme was used to study th…
Catalytic Enantioselective Conjugate Alkynylation of β-Aryl-β-trifluoromethyl Enones Constructing Propargylic All-Carbon Quaternary Stereogenic Cente…
2016
The enantioselective conjugate alkynylation of β-aryl-β-trifluoromethyl enones has been carried out using terminal alkynes and diethylzinc in the presence of 3,3'-bis(perfluorophenyl)BINOL as the chiral ligand to give the corresponding ketones bearing a trifluoromethylated propargylic quaternary stereocenter with fair to good enantioselectivities. Enones bearing a bulky 2-naphthyl attached to the carbonyl group provided the best enantioselectivities. The synthetic applicability of the resulting products has been demonstrated with their iodocyclization to form 4H-pyrans.
Tailoring the ligand structure to the reagent in the mandelamide-Ti(IV) catalyzed enantioselective addition of dimethyl- and diethylzinc to aldehydes
2007
Amides derived from (S)-(+)-mandelic acid in the presence of titanium isopropoxide catalyze the enantioselective addition of dimethyl- and diethylzinc to aldehydes with good yields and ee up to 90%. Because of the modular character of the mandelamides, the structure of the ligand can be tailored to obtain the best results with each reagent. Thus, best results with dimethylzinc are obtained with N-benzyl mandelamide while N-(pyridin-2-yl) mandelamide is the best ligand for the addition of diethylzinc.
ChemInform Abstract: Enantioselective Synthesis of 4-Substituted Dihydrocoumarins Through a Zinc Bis(hydroxyamide)-Catalyzed Conjugate Addition of Te…
2013
Terminal alkynes (II) react with coumarins (I) in the presence of diethylzinc and chiral bis(hydroxyamide) ligands to give enantiopure dihydrocoumarins (III) substituted with an alkynyl group in C(4) position in good enantioselectivities.
Structurally diverse second-generation [2.2]paracyclophane ketimines with planar and central chirality: syntheses, structural determination, and eval…
2005
A set of 20 novel [2.2]paracyclophane ketimines with planar and central chirality has been synthesized from enantiomerically pure and racemic 5-acyl-4-hydroxy[2.2]paracyclophane and alpha-branched chiral amines. Their X-ray structures were determined to elucidate the three-dimensional structures and the absolute configuration. The ketimines were used as catalysts in the asymmetric 1,2-addition reactions of diethylzinc with substituted benzaldehydes to furnish chiral alcohols in up to 95 % ee.
ChemInform Abstract: Catalytic Enantioselective Conjugate Alkynylation of β-Aryl-β-trifluoromethyl Enones Constructing Propargylic All-Carbon Quatern…
2016
The enantioselective conjugate alkynylation of β-aryl-β-trifluoromethyl enones has been carried out using terminal alkynes and diethylzinc in the presence of 3,3′-bis(perfluorophenyl)BINOL as the chiral ligand to give the corresponding ketones bearing a trifluoromethylated propargylic quaternary stereocenter with fair to good enantioselectivities. Enones bearing a bulky 2-naphthyl attached to the carbonyl group provided the best enantioselectivities. The synthetic applicability of the resulting products has been demonstrated with their iodocyclization to form 4H-pyrans.