10.1021/jo402853v
The research focuses on the enantioselective desymmetrization of prochiral diesters to produce lactones with high enantiomeric purity, utilizing a chiral phosphoric acid catalyst. The study is significant for its potential in asymmetric synthesis, particularly for creating biologically active molecules with all-carbon quaternary centers. The experiments involved the preparation of various prochiral diesters through alkylation of di-tert-butyl malonate with different alkyl halides and subsequent reactions to form hydroxy diesters. These diesters were then subjected to desymmetrization using the chiral catalyst in dichloromethane, yielding lactones with high yields and enantioselectivity. The scalability of the process was demonstrated, and the utility of the lactone products was showcased through their conversion into functionalized building blocks. Analyses included NMR for structural confirmation, IR for functional group identification, HRMS for molecular weight determination, and GC and HPLC for assessing enantiomeric excess, providing comprehensive characterization of the synthesized compounds.
10.1002/anie.201109072
The study presents the development of a microporous binol-derived phosphoric acid catalyst for asymmetric organocatalysis. The researchers synthesized a new chiral 1,1’-binaphthalene-2,2’-diol (binol)-derived phosphoric acid (BNPPA) and used it to create a microporous polymer network. This network, which contains the molecular catalyst, ensures high density and accessibility of catalytic centers, leading to fast reaction rates. The BNPPA was used in various asymmetric reactions, including transfer hydrogenation of prochiral benzoxazines, asymmetric Friedel–Crafts alkylation of pyrroles, and aza-ene-type reactions. The microporous polymer network demonstrated high enantioselectivity and activity comparable to its homogeneous counterpart, with the added benefits of being reusable and easily separable. The study highlights the potential of this new heterogeneous catalyst for various asymmetric synthetic transformations.
10.1007/BF00909177
The study investigates the alkenylation of m-cresol by allyl alcohol using various acid catalysts, including phosphoric acid, zinc chloride deposited on aluminum oxide, and cationite KU-1. The researchers found that under certain conditions, the yield of alkenylation products could reach 47% of the theoretical value. The reaction products include isomeric allyl-m-cresols and 2,6-dimethylcoumaran. The study also explores the reaction mechanism, suggesting that the alkenylation proceeds via both C-alkenylation and O-alkenylation pathways, with the O-alkenylation product rearranging to form the ortho isomer and subsequently cyclizing to 2,6-dimethylcoumaran.
10.1002/asia.201101029
The research focuses on the formal synthesis of (-)-Cephalotaxine, an alkaloid with unique pentacyclic structure and antileukemic activity. The study proposes a highly efficient catalytic asymmetric formal synthesis using a tandem hydroamination/semipinacol rearrangement reaction. Key reactants include 1-azaspirocyclic building block 4, alkyne 8, and chiral phosphoric acid 5 as a catalyst. The research involves the synthesis of various substrates 8 with different protecting groups, optimization of reaction conditions, and the examination of the reaction's efficiency and enantioselectivity. Analyses used include chiral-HPLC for determining yields and enantiomeric excess (ee), as well as X-ray crystallography for absolute configuration determination. The study also discovered an enantiomer separation phenomenon on silica gel during purification, which could have implications for the synthesis of other complex compounds.
10.1002/cjoc.201090292
The study investigates the charge-transfer effect on chiral phosphoric acid-catalyzed asymmetric Baeyer-Villiger oxidation of 3-substituted cyclobutanones using 30% aqueous H2O2 as the oxidant. The primary chemicals used include BINOL-derived chiral phosphoric acids as catalysts, 3-aryl cyclobutanones as substrates, and various electron acceptor additives (A1-A7) to modulate enantioselectivity. The purpose of these chemicals is to explore how the intermolecular charge-transfer interaction between the catalyst and electron-deficient additives can fine-tune the enantioselectivity of the asymmetric catalysis, leading to an enhancement of the enantiomeric excess (ee) values in the reaction products.
C, 
Xn, 
T, 
F
C:Corrosive;
