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Diastereomeric reduction of nonactivated, hindered β‐keto and chiral β‐iminoesters are described. The influence of a α‐stereocontrolled center on the efficiency and stereoselectivity of the reduction was studied. Reaction conditions were optimized to synthesize β‐hydroxy‐ and β‐aminoesters in good yields. In the case of chiral β‐iminoesters, influence of matched/mismatched diastereomeric pairs has...
Itraconazole is an antifungal drug widely used in a variety of fungal infections, which have become a significant public‐health problem in recent decades. Itraconazole is a chiral drug consisting of two diastereoisomeric racemates, i.e., four stereoisomers. Data in the literature suggests that stereochemistry may play a significant role in the action and disposition of the drug and therefore stereoselective...
Indolizidine alkaloids have attracted considerable attention because of their vast array of structural diversity and varied biological activity. This article relates the results that we obtained in the field of the total synthesis of indolizidines from α‐amino acids, based on the rhodium‐catalyzed hydroformylation of N‐allylpyrroles intermediates. The formed pyrrolylbutanals undergo an intramolecular...
The distinctive nucleus of kainoid amino acids, (2S,3R)‐(+)‐2‐carboxypyrrolidine‐3‐acetic acid 6, was synthesized by a chemoenzymatic process, exploiting the diastereomeric cis/trans methyl pyroglutamate derivatives 10a, 10b, 10c/11a, 11b, 11c as key intermediates. These mixtures, when subjected to a kinetic resolution mediated by α‐chymotrypsin, reacted diastereo‐, regio‐, and enantioselectively...
The adsorption of diastereoisomers of tartaric acid, namely, meso (R,S)‐tartaric acid, (R,R)‐tartaric acid, and the racemic mixture of (R,R) and (S,S) tartaric acid on the (111) surface of a copper single crystal has been studied by means of reflection‐absorption IR Spectroscopy, X‐ray photoelectron spectroscopy, low‐energy electron diffraction, and thermal desorption spectroscopy. Two distinct adsorption...
Based on a CSD search, a meta‐analysis of 1179 structures of 19 natural amino acids H3NCαH(R)C′(O)O and their derivatives H3NCαH(R)C′(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that the chirality chain with its two steps, established in the preceding paper for alanine, can be extended to natural amino acids. High diastereoselectivities are observed in the induction...
Based on a Cambridge Structural Database (CSD) search, a meta‐analysis of 116 structures of alanine H3NCαH(CH3)C′(O)O and its derivatives H3NCαH(CH3)C′(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that in the first step of a chirality chain, the L configuration at Cα induces (M) and (P) conformations with respect to rotation around the central C′─Cα bond. In the...
This microreview focuses on the nucleophilic ring‐opening of azetidiniums presenting various substitution patterns at C2, C3, and C4. In most cases, the nucleophilic ring‐opening occurred in a stereoselective and regioselective fashion producing functionalized linear amines. Experimental selectivities associated with Density Functional Theory (DFT) calculations have allowed a better understanding...
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