Lipase-catalyzed kinetic resolution of ethyl 3-aryl-3-hydroxypropionate: preparation of the side chain of a novel carbapenem,J-114,870

An optically active 3-aryl-3-hydroxypropionate 3a was prepared by lipase-catalyzed kinetic hydrolysis of a diastereomeric mixture of 3-aryl-3-(α-chloroacetoxy)propionate 6 in good conversion yield with adequate purity (>95% de). This enzymatic reaction proceeded with great efficiency as measured by reaction rate, chemical yield and stereoselectivity. The compound 3a was converted to J-114,870 1a, a novel ultra-broad spectrum carbapenem, without significant epimerization.     

Synthetic studies on neomarinone: practical and efficient stereoselective synthesis of the side chain

A practical and efficient stereoselective synthesis of the side chain of neomarinone is reported. The synthesis was achieved in six steps (41% overall yield) from 2-methyl-2-cyclohexenone. The key step is a novel stereoselective 1,4-conjugate addition/enolate alkylation by an epoxide-opening reaction.     

Synthesis of a new carbapenem with a 6-methyl hydroxyacetate side chain

The synthesis of the 2-(4-pyridinylthio)-carbapen-2-em-3-carboxylic acid 1b, bearing a 6-methyl hydroxyacetate side chain, is described.     

Diastereoselective synthesis of (2R,4R)-2-aryl-4-hydroxypyrrolidine: preparation of the side chain of novel carbapenem.

Improved synthesis of the trans-3,5-disubstituted pyrrolidin-3-ylthio side-chain of the novel carbapenem 1 was achieved via stereoselective reduction of the 1-aryl-1-butanone derivative 5 and successive intramolecular cyclization of the resulting chiral alcohol 6. The 1-aryl-1-butanone derivative 5 was obtained by a coupling reaction of protected 4-hydroxy-2-pyrrolidone with aryl-Grignard reagent.     

A novel and efficient route for the preparation of atorvastatin

A novel and efficient synthetic method of atorvastatin was described.The key step of the synthesis was the construction of the olefin linkage between the chiral side chain and skeleton via a Horner-Wadsworth-Emmons reaction,resulting in the advanced intermediate of atorvastatin under hydrogenation of the olefin over Pd/C.This novel method is more useful for the practical synthesis of atorvastatin than its document reported methods.     

Synthesis of the side chain of a novel carbapenem via iodine-mediated oxidative cyclization of (1R)-N-(1-aryl-3-butenyl)acetamide

A (2R,4S)-trans-disubstituted pyrrolidine ring system was constructed by employing iodine-mediated oxidative cyclization of (1R)-N-[1-(4-bromophenyl)-3-butenyl]acetamide 3 as a key step. The resulting diastereomeric mixture of (2R)-2-aryl-4-acetoxypyrrolidine 4 was stereoselectively converted to the side-chain of a novel ultrabroad-spectrum carbapenem 1, via (2R,4R)-2-aryl-4-hydroxypyrrolidine 7.     

An efficient enantioselective synthesis of the acyl side chain of polyoxypeptins

An enantioselective synthesis of the acyl side-chain 3 of polyoxypeptins 1 and 2 was achieved by the Sharpless AE, with subsequent regioselective opening of the epoxyalcohol using a Grignard reagent in the presence of CuI, and an aldol condensation using Seebach's ester. The method reported has the advantage of a concise route and excellent enantiomeric purity, as well as starting from readily available chemical substrates and the use of inexpensive reagents.     

A novel synthetic approach to the ecdysone side chain via furan derivatives

A New type of synthesis of (22R)-22,25-dihydroxycholesterol and its 22S isomer from pregnenolone by using furan derivatives is reported.     

A novel procedure for the preparation of zinc reagents: a practical synthesis of (+)-biotin

The use of bromine for activation of zinc dust allowed smooth and reproducible reduction of iodide 1 to the corresponding zinc reagent 2. The zinc reagent 2 obtained by the present protocol was allowed to the Fukuyama coupling reaction with thiolactone 3 to provide a key intermediate 4 for (+)-biotin in high yield using a reasonably fair amount of 1 (1.4 equiv).     

An efficient and green protocol for the preparation of cycloalkanols: a practical synthesis of venlafaxine

The condensation of arylacetonitriles with cyclic ketones using aqueous NaOH or KOH under phase transfer catalysis gives almost quantitative yields of cycloalkanols. This protocol is utilized for a practical synthesis of the antidepression drug, venlafaxine 1.     

新型LB成膜材料-两亲性侧链取代酞菁锌的合成

本文合成了一种新型的两亲性硬脂酸侧链取代的酞菁化合物, 利用LB膜技术制备了酞菁化合物与正十六烷混合的单层和多层LB膜, LB膜内酞菁分子大环与基片大体平行, 表明该分子具有良好的成膜性能。     

An efficient and practical chemoenzymatic preparation of optically active secondary amines

[reaction: see text] An efficient and practical chemoenzymatic method was developed for the preparation of a variety of chiral secondary amines. Here, oxalamic esters were identified as unique derivatives amenable to the enzyme-catalyzed kinetic resolution of racemic secondary amines. Both enantiomers of the amines were produced in high optical purity and yields after the cleavage of the oxalamic groups.     

Efficient one-pot synthesis of the 2-aminocarbonylpyrrolidin-4-ylthio-containing side chain of the new broad-spectrum carbapenem antibiotic ertapenem

An efficient synthesis of the 2-aminocarbonylpyrrolidin-4-ylthio containing side chain of ertapenem (MK-0826) is described. Starting material N-(O,O-diisopropyl phosphoryl)-trans-4-hydroxy-L-proline is converted in a one-pot process to (2S)-cis-3-[[(4-mercapto-2-pyrrolidinyl)carbonyl]amino]benzoic acid monohydrochloride in 70-75% overall yield via a series of six reactions. The development of each of these reactions and the isolation of the product is discussed in detail.     

Systematic and efficient side chain optimization for molecular docking using a cheapest‐path procedure

Molecular docking of small‐molecules is an important procedure for computer‐aided drug design. Modeling receptor side chain flexibility is often important or even crucial, as it allows the receptor to adopt new conformations as induced by ligand binding. However, the accurate and efficient incorporation of receptor side chain flexibility has proven to be a challenge due to the huge computational complexity required to adequately address this problem. Here we describe a new docking approach with a very fast, graph‐based optimization algorithm for assignment of the near‐optimal set of residue rotamers. We extensively validate our approach using the 40 DUD target benchmarks commonly used to assess virtual screening performance and demonstrate a large improvement using the developed side chain optimization over rigid receptor docking (average ROC AUC of 0.693 vs. 0.623). Compared to numerous benchmarks, the overall performance is better than nearly all other commonly used procedures. Furthermore, we provide a detailed analysis of the level of receptor flexibility observed in docking results for different classes of residues and elucidate potential avenues for further improvement. © 2013 Wiley Periodicals, Inc.