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Gef��rdert im Rahmen des Projekts DEAL

Die vorliegende Arbeit beschäftigt sich mit der Isolierung und der strukturellen Charakterisierung der Cyanido-substituierten metallierten Ylide [Ph\(_3\)PCCN]M (M = Li, Na, K) mit Lithium, Natrium und Kalium als Metallkationen. Im Festkörper konnten in Abhängigkeit vom Metall und zusätzlichen Lewis-Basen unterschiedlichste Aggregate bestimmt werden. Ebenfalls wurden die metallierten Ylide als vielseitige Nukleophile für den einfachen Zugang zu Ylid-substituierten Verbindungen eingesetzt. Halogenierungen, Carbonylierungen und Funktionalisierungsreaktionen mit Hauptgruppenelement Halogeniden ließen sich leicht durch einfache Abfangreaktionen mit den entsprechenden Elektrophilen durchführen. Die Monoylid- und Diylid-funktionalisierten Phosphanen wurden erfolgreich in der Gold(I)-Katalyse getestet. Hierbei konnten wegweisende Erkenntnisse über die Auswirkungen der Ylid-Substitution auf die Phosphan-Liganden erhalten werden, um so zukünftiges Ligandendesign zu verbessern.

Diese Dissertation befasst sich mit der Synthese eines stabilen metallierten Ylids. Die elektronische Struktur und Reaktivität des metallierten Ylids wurden im Detail untersucht und es konnte ein Ylid-stabilisiertes Borkation hergestellt werden. Außerdem konnte eine Reihe von Ylid-substituierten Phosphanen hergestellt werden. Diese Phosphane sind sehr elektronenreiche und sterisch anspruchsvolle Liganden und eine Reihe von Übergangsmetallkomplexe dieser Liganden konnten untersucht werden. Die Ylid-substituierten Phosphane konnten ebenfalls als Liganden in Übergangsmetall-katalysierten Reaktionen eingesetzte werden. So konnten zwei unterschiedliche Systeme entwickelt werden, die jeweils hohe Aktivität in der Gold-katalysierten Hydroaminierung und in der Buchwald-Hartwig-Kupplung von Arylchloriden mit Aminen zeigten.

In this thesis g-amino-a-diazo-b-keto esters were synthesized from a-amino acids. The syntheses were done on two different ways. On both ways racemization occurred. The derivatives with a fully protected amino function were decomposed by Rh- and Ru-based catalysts. Products of the resulting carbenoid reaction pathways were isolated and identified. Two routes were possible: First, reaction with the main chain of the amino acid. On this route novel functionalized ali and hetero cycles were gained. In the second route, the reaction occurred with the phthalimido protecting group. In that case, a carbonyl ylide was formed, if a dipolarophile added to the decomposition a [3+2]-cycloaddition took place. Without adding a dipolarophile, a dimer was the product obtained.

The most important inhibitory neurotransmitter in human brains, gamma-amino butyric acid (GABA), and the gastroprotective natural product AI-77-B are two prominent examples for gamma-amino acids. In the thesis here present a flexible stereoselective synthesis of alpha-hydroxy-gamma-amino acids was developed. The aim was to get an access to new GABA-analogs, which dispose of promissing potential in pain treatment, and to lipophilic derivatives of AI-77-B. Starting from allylic sulfoximines the desired alpha-hydroxy-gamma-amino acids could be obtained with up to 34% yield over six steps. The key steps were a titanium mediated hydroxyalkylation reaction under selective construction of two stereo centers and a double bond, a highly diastereoselective aza-Michael-cyclisation and the creation of the acid moiety by oxidative degradation of a furan ring. The employed chiral auxiliary (S)-N,S-dimethyl-S-phenylsulfoximine could be recovered as a sulfinamide isolated in enantiomerically pure form. There are literature known methods for its transformation into the starting chiral auxiliary. Moreover a new one step method for the cleavage of the sulfoximine moiety under introduction of an iodine atom was developed. Considering the multifaceted chemistry of iodine compounds, especially in regard to C-C-bond formation, this opens up a multitude of new possibilities. The newly developed method has already found further application in our research group. Within the research about furan derivatives the idea to replace the oxygen heterocycle with a nitrogen heterocycle, namely pyrrole, was born. This would allow for a short synthesis of gamma-lactams, the cyclic analoga of gamma-amino acids. Gamma-lactams are a class of highly interesting compounds. The structural motive can be found frequently in nature and also pharmacologically active compounds are among them. Possible pathways to achieve this synthesis were shown. A further topic of this thesis were synthesis and structure elucidation of new cyclic aminosulfoxonium ylides. Homoallylic sulfoximines were activated by N-methylation. Treatment with base induced a five-step one-pot domino reaction in the course of which two new ring systems were established stereoselectively. The proposed structures were confirmed by X-ray structure analysis of a very similar compound. Compounds of this type could serve as building blocks for highly substituted cyclopentanones. The performance of the versatile sulfoximine chiral auxiliary for asymmetric syntheses was clearly demonstrated by means of described examples.

La reaction de (E)-ClSi(CH 3 ) 2 C(R 3 )=C(C 2 H 5 )B(C 2 H 5 )Cl [R 3 =CH 3 (A) ; R 3 =C(CH 3 )=CH 2 (B) avec LiS(CH 2 ) n SLi (n=2 a 4) donne des derives de Thionathiasilaboratabicycloalcene. Ces composes se coordinent avec Fe(CO) 4 et Cr(CO) 5 . La reaction de 1,2-bis[lithiothio] benzene avec C(A) fournit un derive de thionathiasilaboratatricyclododecatetraene. Analyse de sa structure par RX. La reaction de 1,3-bis [lithiothio] benzene avec (A) conduit au (hexamethyl tetradeshydro tetraethyl) tetrathiadisilodibora [«6.6»] metacyclosphane