Up to now only few examples of cyclopropane syntheses by NORRISH-YANG-reaction are known. In most of these cases an initial PET to the excited carbonyl group was proven or seems very likely basing on the modern state of knowledge. [1,2] In the following we would like to present a new method to prepare highly functionalized cyclopropanes. It is well known by the chemistry of monoradicals that radical centres are excellent neighbouring groups for the nucleophilic substitution. [3,4] The -hydroxy radicals 1 occupy a special position. If X is a suited leaving group the elimination of the acid HX occurs without formation of any ionic intermediates and with rate constants k > 109 s-1. [5,6] It is noteworthy, in the formed enolate radical 2 the highest spin density is now mainly localized at the adjacent carbon atom.

Radical cyclizations offer an easy access to five- and six-membered rings, and their applications to the synthesis of complex molecules are now incredibly numerous.1 The control of stereochemistry in theses processes is generally high and models have been designed which allow to make fairly good predictions.2-3 Carbohydrates have been used as chiral template for the construction of highly substituted cyclopentane derivatives and they provide a variety of stereochemically well defined starting materials which could be used to evaluate the influence of polysubstituted ethylenic tethers on the stereochemical balance of 5-exo ring closures.

A new synthesis of 5-substituted a,b-unsaturated g-lactams is reported. b-[Cp(CO)2Fe]-Substituted N-sulfonyl1 and Nsulfinyl azadienes 1 react with Grignard reagents or organolithium compounds furnishing 5-substituted a,b-unsaturated g-lactams 3.2,3 These reaction cascades occur by initial attack of the organometallic reagent at the imine functionality followed by an intramolecular cyclocarbonylation step. In a number of cases non-N-protected lactams are obtained from N-sulfonyl azadienes besides the desired N-sulfonyl g -lactams 3. Moreover, chiral b-[Cp(CO)2Fe]-substituted N-sulfinyl azadienes 1 react with the organometallic reagents to furnish exclusively 5-substituted non-N-protected g - lactams 3.2,3

Organoselenium reagents are largely used in organic synthesis to introduce new functional groups into organic substrates under very mild experimental conditions.[1] In recent years, several research groups have described the synthesis of a number of chiral non racemic diselenides which can be transformed in situ into electrophilic selenenylating agents to effect efficient asymmetric syntheses.[2][3][4][5][6][7] Diselenides containing a nitrogen atom in the chiral moiety have also been employed as useful ligands in various transformations such as diethilzinc additions to aldehydes,[8] asymmetric hydrosilylation[9] and transfer hydrogenation reactions.[10] Moreover these diselenides can also be employed in the sequential catalytic stereoselective oxyselenenylation-elimination reactions using ammonium persulfate to generate the electrophilic selenenylating species and to promote the elimination process.[11] Herein we report the synthesis of two new chiral nitrogen containing diselenides and the use of these compounds as precursors of electrophilic species in asymmetric additions of organoselenium reagents to olefins.

The Cu-catalyzed intramolecular CH insertion of phenyliodonium ylide 5b has been investigated at 0 °C in the presence of several chiral ligands. Enantioselectivities vary in the range of 38–72 %, and are higherthan those resulting from reaction of the diazo compound 5c at 65 °C. The results are consistent with a carbenoid mechanism for Cu-catalyzed decomposition of phenyliodonium ylides.

In order to develop a practical method for the construction of chiral molecules, we have designed a novel chiral system possessing two metal centers utilizing tartaric acid esters. Based on this concept, catalytic asymmetric 1,3-dipolar cycloaddition of nitrile oxides and nitrones could be achieved with an high level of stereocontrol.

There is growing interest in asymmetric variant of sigmatropic rearrangements. We have recently initiated a programme aimed at developing the amino-Cope rearrangement as a novel synthetic protocol.

Meso-tetraphenylporphyrin (TPP) and its derivatives are commonly used for the construction of photosynthetic model compounds,1 enzyme mimetics, and artificial receptors.2 Also, with regard to materials sciences, TPPs are found for example in dendrimers,3 as liquid crystalline materials with discotic behavior,4 and as part of optoelectronic devices.5,6 Since the derivatization of TPPs has been well studied, it is possible to tailor their properties allowing adaption into the desired specific environment. Obviously, novel materials containing porphyrins have become a major research field in porphyrin chemistry. It appears to us that by using the inherent geometry of porphyrins interesting new conjugates would be available. In this paper we wish to introduce a series of polymalonates derived from bromomethylated tetraarylporphyrins, which are useful precursors for nucleophilic substitutions

The generation of the 1,2,4-triazolyl cation (1) has been attempted by the thermolysis and photolysis of 1-(1,2,4-triazol-4-yl)-2,4,6-trimethylpyridinium tetrafluoroborate (2) and the thermolysis of 1- and 4- diazonium-1,2,4-triazoles, using mainly mesitylene as the trapping agent. Thermolysis of (2) gave mostly 1,2,4- triazole, together with 3-(1,2,4-triazol-4-yl)-2,4,6-trimethylpyridine, 4-(1,2,4-triazol-4-ylmethyl)-2,6- dimethylpyridine and 4-(2,4,6-trimethylbenzyl)-2,6-dimethylpyridine. Thermolysis of each of the diazonium salts in mesitylene again gave mainly triazole together with very low yields of 1-(1,2,4-1-yl)-2,4,6- trimethylbenzene and the corresponding -4-yl isomer in about the same ratio. On the other hand, photolysis of (2) in mesitylene gave mainly 1-(1,2,4-triazol-1-yl)-2,4,6-trimethylbenzene. A photoinduced electron transfer from mesitylene to (2) has been observed and preliminary laser flash photolyses of (2) and the corresponding 2,4,6-triphenylpyridinium salt have been carried out. The o served transients are explained as arising from the first excited states of the pyridinium salts rather than from (1). Ab initio MO calculations are reported and indicate that the predicted electronic ground-state of the triazolyl cation is a triplet state of B1 symmetry with five p electrons, which corresponds to a diradical cation (1c). Possible mechanisms for the formation of the various products are proposed.

The NiCl2·2H2O/Li/DTBB (10 mol%) combination allows the reduction of aromatic hydrazines 1 (to amines), azo compounds 2 (to primary amines), azoxy compounds 3 (to azo compounds or to primary amines, depending on the reaction conditions) or amine N-oxides 4 (to tertiary amines), under mild reaction conditions (THF, room temperature). The reaction can be alternatively carried out in the presence of a polymer supported arene instead of DTBB as electron carrier.