Enantioselective Addition of Diethylzinc to Aromatic Aldehydes Catalyzed by Pyrolidine and Piperidine β-Amino Alcohols
摘要:
The enantioselective alkylation of aryl aldehydes by diethylzinc in the presence of catalytic amounts of several chiral pyrolidine- and piperidine-based amino alcohol ligands, synthesized from the reaction of (R)-2-amino-1-butanol and (S)-2-amino-3-phenylpropan-1-ol with appropriate dibromoalkanes, was studied. The influence of temperature and ligand structure has been investigated. Addition of diethylzinc to aromatic aldehydes under the optimized condition gave the corresponding products in excellent yields with ee values of up to 77%.
Catalytic enantioselective arylation of aldehydes: boronic acids as a suitable source of transferable aryl groups
作者:Antonio L. Braga、Diogo S. Lüdtke、Fabrício Vargas、Marcio W. Paixão
DOI:10.1039/b501485a
日期:——
The catalytic enantioselective arylation of several aldehydes using boronic acids as the source of transferable aryl groups is described; the reaction is found to proceed in excellent yields and high enantioselectivities (up to 97% ee) in the presence of a chiral amino alcohol.
Nucleophilic Fluorination and Radiofluorination via Aziridinium Intermediates: N-Substituent Influence, Unexpected Regioselectivity, and Differences between Fluorine-19 and Fluorine-18
作者:Marie Médoc、Franck Sobrio
DOI:10.1021/acs.joc.5b01714
日期:2015.10.16
reaction was heated to 90 °C, considerable changes appeared during radiofluorination. In the latter case, the radiochemical yields increased, and degradation of the 2-fluoro-propan-1-amine isomer (b) occurred, leading to a regiospecific reaction in the radiolabeling of [18F]-fluorodeprenyl. This method involving nucleophilicradiofluorination at RT was successfully applied to the radiolabeling of [18F]-2-fluoroethylamines
C-H Functionalization of Amino Alcohols by Osmium Tetroxide/NMO or TPAP/NMO: Protecting Group-Free Synthesis of Indolizidines (-)-223AB and 3-<i>epi</i>
-(-)-223AB
作者:Wei-Lun Chen、Lee-Ya Wang、Yu-Jang Li
DOI:10.1002/ejoc.201901494
日期:2020.1.9
perruthenate, with NMO provide N,O‐acetal moieties by trapping the resulting iminium ion with the alcohol. These two transformations were demonstrated in the protecting group free synthesis of indolizidines (–)‐223AB and 3‐epi‐(–)‐223AB, compounds found in dart‐frog poison.
The enantioselective alkylation of aryl aldehydes by diethylzinc in the presence of catalytic amounts of several chiral pyrolidine- and piperidine-based amino alcohol ligands, synthesized from the reaction of (R)-2-amino-1-butanol and (S)-2-amino-3-phenylpropan-1-ol with appropriate dibromoalkanes, was studied. The influence of temperature and ligand structure has been investigated. Addition of diethylzinc to aromatic aldehydes under the optimized condition gave the corresponding products in excellent yields with ee values of up to 77%.