Enantioselective syntheses of bicyclo[3.1.0]hexane carboxylic acid derivatives by intramolecular cyclopropanation

Enantioselective syntheses of bicyclo[3.1.0]hexane carboxylic acid derivatives are described. The syntheses were achieved by an intramolecular cyclopropanation as the key step, starting from enantiomerically pure starting materials that are commercially available.     

贫电子环丙烷衍生物的化学

综述了贫电子环丙烷衍生物——顺式-1,2-二取代-6,6-二烷基-5,7-二氧螺- [2,5]-4,8辛二酮与含氧、氮、硫等亲核试剂反应的研究进展。     

X-Ray Investigation of (E)-2-phenyl-1-chlorocyclopropane-1-carboxylic Acid — A Convenient Synthon for Transamine Synthesis

A method for the synthesis of (E,Z)-2-phenyl-1-chlorocyclopropane-1-carboxylic acid by the addition of ethyl trichloroacetate to styrene in the presence of copper(I) ammine complexes is suggested. The major isomer was isolated as the corresponding acid. The results of X-ray diffraction (XRD) analysis unequivocally prove that the benzene ring and the carboxylic group are in the cis-position and that the molecules form centrosymmetric dimers. (E)-2-phenyl-1-chlorocyclopropane-1-carboxylic acid can serve as a convenient synthon for transamine synthesis.     

Radical Ring‐Opening Polymerization Behavior of 1,1‐Dicyano‐2‐Vinylcyclopropane and Its Copolymerization with 1‐Cyano‐1‐Ester‐2‐Vinylcyclopropane

Radical ring‐opening polymerization of 1,1‐dicyano‐2‐vinylcyclopropane 1 was performed in benzonitrile to find the corresponding homopolymer 2 soluble in organic solvents was successfully obtained while that in other solvents gave crosslinked and thus insoluble homopolymer. In addition, 1 underwent radical copolymerization with 1‐cyano‐1‐ester‐2‐vinylcyclopropanes 3 and 4 to afford the corresponding copolymers 7 and 8 . By increasing the content of the 1 ‐derived unit in the resulting copolymers, the solubility of the copolymers in organic solvents became lower and the residual weights at 600 °C and their glass transition temperatures became higher. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1723–1729     

Mechanism of magnesium carbenoid 1,3‐C–H insertion: a DFT study

The 1,3‐C–H insertion of magnesium carbenoid and related species was investigated via density functional theory (DFT) calculations. The 1,3‐C–H insertion occurred according to an S_N2‐like mechanism wherein the nucleophilic C–H bond attacked the electrophilic carbenoid carbon atom. The activation energies for the 1,3‐C–H insertion of (1‐chloropropyl)magnesium chloride, (1‐methoxypropyl)magnesium chloride, and [1‐(methylthio)propyl]magnesium chloride were 20.0, 33.8, and 47.1 kcal/mol, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Cyclopropane analogue of valine: influence of side chain orientation on peptide folding

The cyclopropane analogue of valine (1-amino-2,2-dimethylcyclopropanecarboxylic acid, c₃Val) has been synthesised and incorporated into the model peptides ^tBuCO-l-Pro-l-c₃Val-NHⁱPr and ^tBuCO-l-Pro-d-c₃Val-NHⁱPr. In the solid state, both dipeptides accommodate a type II β-turn stabilised by an NHⁱPr to ^tBuCO hydrogen bond. Remarkably, the peptide incorporating l-c₃Val also exhibits a distorted γ-turn around the cyclopropane residue, with Pro-CO and NHⁱPr intramolecularly hydrogen-bonded.     

一类环丙烷螺环化合物的简易合成和结构表征

以乙二醇二甲醚为溶剂,在K2CO3及痕量水存在下,鉮盐和多取代贫电子烯烃反应,高立体选择性合成了顺-1-甲氧羰基-2-取代芳基-6-环己烷基-5,7-二氧杂螺-〔2,3〕-4,8-二酮。采用IR、MS、1H NMR、13C NMR、DEPT及二维核磁共振技术对所合成的化合物进行了结构表征,并以NOESY实验确定了该化合物为顺式结构的环丙烷衍生物。