手性螺-环丙烷类化合物的结构特征和解析

通过IR,¹HNMR,¹³CNMR,UV,MS以及X射线晶体衍射测定方法来确认一类新的手性螺-环丙烷化合物的化学结构.为研究新的螺环/环丙烷类复杂化合物的结构提供了有价值的依据.     

Syntheses and Applications of Monofluorinated Cyclopropanes

The combination of a fluorine atom and a cyclopropane ring, which both possess unique structural and chemical features, can generate new relevant building blocks for the discovery of efficient fluorinated biologically active agents. In this review, we report the different strategies to access monofluorocyclopropanes and highlight some of their attractive biological applications.     

Versatility in the Brook Rearrangement for the Selective Ring-Opening of Three-Membered Rings

From a single α-silylated carbinol intermediate, easily accessible by carbometallation of cyclopropenes, various scaffolds featuring a quaternary carbon stereocenter could be obtained selectively. The selectivity towards these different products was achieved by either changing the experimental conditions or the nature of the organometallic species involved.     

Synthesis of the Key Disaccharide of 3′-Sulfo Lewis X and Lewis A: The Novel E-Selectin Ligand

Benzyl 2,4,6-tri-O-benzyl-β-D-galactopyranoside (6) was synthesised from regioselective protection of stannylated benzyl 2,6-di-O-benzyl -β-D-galactopyranoside (3) with 4-methoxybenzyl chloride, followed by benzylation and oxidative removal of the temporary protecting group. The disaccharide (2) was prepared by condensation of the common acceptor 6 with 7 through thial activation as well as with 8 following Konigs Knorr procedure.     

Unprecedented dual reactivity of anhydrous potassium hydroxide in cascade cyclopropannelation/Haller-Bauer-scission/Grob-fragmentation reactions

We report an unprecedented type of reactivity of ‘anhydrous potassium hydroxide’ (‘APH’) in which it plays, over a large variety of related educts, sequentially the role of base and nucleophile. Some insight into the structure of reactive species as well as comparative reactivity of related reagents prepared by fusion of commercially available potassium hydroxide or by adding stoichiometric amount of water to potassium hydride is provided.     

Synthesis of Functionalized 2‐Aminopyrroles by Lewis Acid Catalyzed Ring‐opening of 1,1,2,3‐Tetrasubstituted Cyclopropanes with Arylamines

Under the catalysis of Lewis acid Co(ClO₄)₂ the reaction of the sterically hindered 1,1,2,3‐tetrasubstituted cyclopropanes with arylamines in refluxing THF gave the functionalized 2‐aminopyrroles with sequential ring‐opening of cyclopropane, nucleophilic substitution, nucleophilic addition of cyano group and recyclization processes.     

C sp 3-H bond activation triggered by formation of metallacycles: rhodium(I)-catalyzed cyclopropanation/cyclization of allenynes

Giving direction: An C?sp?3-H bond activation directed by a rhodacycle intermediate has been found to occur in a Rh(I)-catalyzed reaction between an allene moiety having a tert-butyl substituent, and tethered alkynes. Cyclic compounds containing a cyclopropane ring were obtained in good to high yields (up to 92%).