Nitsa Galili

The First Direct Synthesis of Corroles from Pyrrole

The solvent-free, catalyst-free condensation of pyrrole and aldehydes provides an extremely facile synthetic pathway to novel corroles [Eq. (1); Ar=C6 F5 , 2,6-F2 C6 H3 , 2,6-Cl2 C6 H3 ]. The product containing pentafluorophenyl groups is an excellent precursor of other derivatives, including an ionic, water-soluble corrole.

Erste direkte Synthese von Corrolen aus Pyrrol

Die losungsmittel- und katalysatorfreie Kondensation von Pyrrol und Aldehyden bietet einen auserst einfachen Zugang zu neuartigen Corrolen [Gl. (1); Ar = C6F5, 2,6-F2C6H3, 2,6-Cl2C6H3]. Das Pentafluorphenyl-substituierte Produkt (Ar = C6F5) ist eine exzellente Vorstufe fur andere Derivate, einschlieslich eines ionischen, wasserloslichen Corrols.

METALLOPORPHYRIN CATALYZED ASYMMETRIC CYCLOPROPANATION OF OLEFINS

Abstract Asymmetric cyclopropanation of styrene by an enantiopure carbenoid under catalysis by simple metalloporphyrins was found to be much more efficient and selective than the alternative approach, the combination of metal complexes of enantiopure porphyrins and a non-chiral diazoester.

N-SUBSTITUTED CORROLES : A NOVEL CLASS OF CHIRAL LIGANDS

Although known for almost 35 years, N-substituted corroles have only now been recognized as being chiral. Several examples of these species were prepared in a facile two-step synthesis and separated into their enantiomers by HPLC. The zinc(II) complex of the corrole shown schematically was also synthesized.

First catalysis by corrole metal complexes: epoxidation, hydroxylation, and cyclopropanation

The first ever application of corroles shows that their metal complexes are good catalysts, almost as potent as the corresponding metalloporphyrins in the oxygenation of hydrocarbons by iodosylbenzene and superior for the cyclopropanation of olefins by carbenoids.

STEREOSELECTIVE CYCLOPROPANATION WITH A SULTAM CARBENOID

Abstract Stereoselective cyclopropanation of alkenes with the Oppolzers sultam carbenoid was examined for the first time. The addition reaction proceeds in high yields on substituted alkenes and provides an easy access for stereoselective preparation of di- and tri-substituted cyclopropanes. The synthetic utility of the litle reaction was demonstrated in the stereoselective preparation of 1.

A novel synthesis of protected glucose intermediates

The 1,2,4,6-Tetra-O-pivaloyl-D-gluco-pyranose 3 and 1,2,3,6-Tetra-O-pivaloyl-D-gluco-pyranose 4 have been prepared in one step from anhydrous glucose and pivaloyl chloride. These new intermediates can be converted into the corresponding esters, or used in the synthesis of a disaccharide in good yield. Thus, 2,3,6-Tri-O-pivaloyl-gluco-pyranose 10 can be prepared from 4, and used for preparation of β-gluco derivatives via the corresponding trichloroacetimidate 12.

Highly efficient trapping of short-lived 1,4-diradicals, the order of first bond formation in the intramolecular photocycloaddition of 3-(4′-pentenyl)-cyclohex-2-enones

Abstract Complete trapping of 1,4-diradical intermediates, formed in the intramolecular [2+2] photocyclo-addition of 13, provide direct evidence for the exclusive formation of the first bond at the C(β) of the cyclic enone. This result is found in full agreement with the previously studied compounds 1.

The order of first bond formation in the intramolecular photocycloaddition of 2-(4′-pentenyl)-cyclohex-2-enones

Abstract Complete trapping of 1,4-diradical intermediates, formed in the photocycloaddition of 9, provide direct evidence that first bond formation takes place at either C(α) or C(β) positions of the cyclic enone. No cleavage of the 1,4-diradical 10 or endo-diradical intermediates 11 and 12 could be detected. However, partial cleavage of the exo-diradical intermediates 13 and 14 was measured. Unusual long-range aromatic radical substitution was obtained in a competing rate with the cyclopropyl carbinyl radical rearrangement.