Ferrocene derived P,S-heterodonor ligands were effectively used in AgOAc catalyzed asymmetric cycloaddition of azomethine ylides. The roles of planar chirality and electronic properties of the phosphorous substituents have been examined, and up to 93% ee was obtained. 2007 Elsevier Ltd. All rights reserved. The 1,3-dipolar cycloaddition reaction has become a powerful synthetic tool, providing a...

The reaction of 17,17-dichloro-androst-16(E)-chloromethylene with secondary amine base afforded substitution products exocyclic D-ring ketones, in contrast to the alkaline which cleaved steroidal des-D formyl alkyne. alkyne was employed prepare annulated isoxazolo steroid via 1,3-dipolar nitrile oxide cycloaddition reaction.

Benzonitrile oxide (la) reach with 1,1,2,2,3,3-hexamethyl-4,5-bis(methylene)cyclopen~e (5) to give a mixture of the 1,3-dipolar cycloaddition product 8 and the oxime 9. This reaction is 26 times slower than the corresponding reaction of la with 1,2-bis(methylene)cyclopentane (15), which exclusively yields the 2-isoxazoline 19. With the assumption that the oxime 9 is generated by a stepwise proc...

Few-layer graphenes (FLG) produced by dispersion and exfoliation of graphite in N-methylpyrrolidone were successfully functionalized using the 1,3-dipolar cycloaddition of azomethine ylides. The amino functional groups attached to graphene sheets were quantified by the Kaiser test. These amino groups selectively bind to gold nanorods, which were introduced as contrast markers for the identifica...

A highly regio- and stereoselective synthesis of bispirooxindoles by 1,3-dipolar cycloaddition of in situ generated azomethine ylides from isatin and proline to different electron-deficient alkenes has been developed. The synthesis affords the desired bispiro scaffold compounds in excellent yields with high regioselectivity under mild conditions. The stereochemistry was determined by single-cry...

Oligonucleotides including C-nucleotides having 1-substitued 1H-1,2,3-triazoles as artificial nucleobases were conveniently synthesized by the post-elongation modification method using the copper(I)-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) reaction. The base-pairing properties of the triazole nucleobase analogs in forming duplexes with oligonucleotides were investigated by the T...

The first total synthesis of (+)-5-epi-eudesm-4(15)-ene-1β,6β-diol has been achieved in 12 steps starting from the known (-)-cis-piperitol and by using a chelation controlled glycolate enolate Ireland-Claisen rearrangement and an intramolecular nitrile oxide dipolar cycloaddition as key steps.

An efficient synthesis of pyrazoles from tosylhydrazones and nitroalkenes was developed. In comparison with the previously reported 1,3-dipolar cycloaddition reaction of diazo compounds with electron-deficient alkenes or alkynes, this methodology proceeded with a sequential Baylis-Hillman/intramolecular cyclization mechanism and a variety of reversed regioselectivity products were prepared in g...

The copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) was used for the first time to attach a biologically active carbon monoxide delivery agent to modified nanodiamond (ND) as a highly biocompatible carrier. The [Mn(CO)(3)(tpm)](+) photoactivatable CO-releasing molecule (PhotoCORM) on the surface retained the carbon monoxide release properties of the parent compound as shown with...

The construction of multivalent structures such as sugar heterodimers, glycoclusters, calix sugars, multicalixarenes, and glycocyclodextrins is designed by using 1,3-dipolar cycloaddition as a versatile and efficient tool which allows the creation of heterocyclic bridges between the different units that are coupled.