Matthias Lotz

New Applications of Polyfunctional Organometallic Compounds in Organic Synthesis

In the second half of the twentieth century much effort was invested in the preparation of highly reactive polar organometallic reagents. The high reactivity of these reagents precluded the presence of many functional groups and often good chemoselectivities and stereoselectivities could only by achieved by transmetalation reactions. The synthesis of increasingly complex target molecules and the desire to avoid tedious protection-deprotection steps has led inevitably to the use of functionalized organometallic reagents in retrosynthesis. In the last fifteen years, the generation of organic derivatives of numerous metals and metalloids (Li, Mg, B, Zn, Sn) was investigated. In this review the most important preparations and applications of organometallic reagents in organic synthesis will be covered, with particular emphasis on organozinc reagents.

Neue Anwendungen für polyfunktionalisierte Organometallverbindungen in der organischen Synthese

In der zweiten Halfte dieses Jahrhunderts wurde viel Forschungsarbeit in die Herstellung polarer Organometallreagentien investiert. Die hohe Reaktivitat dieser Reagentien schloss die Gegenwart funktioneller Gruppen aus, und gute Chemo- und Stereoselektivitaten waren oft nur durch Transmetallierung zu erreichen. Die Synthese immer komplexerer Zielverbindungen und der Wunsch, ohne umstandliche Schutzgruppenstrategien auszukommen, fuhrten dazu, funktionalisierte Organometallreagentien in Retroynthesen zu verwenden. In den letzten 15 Jahren wurde die Herstellung organischer Derivate zahlreicher Metalle und Halbmetalle wie Li, Mg, B, Zn und Sn untersucht. Dieser Aufsatz fasst die wichtigsten Herstellungsmethoden und Anwendungen metallorganischer Reagentien in der organischen Synthese zusammen, wobei der Schwerpunkt auf Organozinkverbindungen liegt.

New P,N-ferrocenyl ligands for rhodium-catalyzed hydroboration and palladium-catalyzed allylic alkylation

A set of nine new chiral P,N-ferrocenyl ligands for metal-catalyzed enantioselective reactions has been prepared. The rhodium-catalyzed hydroboration of styrene with catechol borane proceeded with high regioselectivity (up to 97:3) or with high enantioselectivity (up to 92% ee) depending on the catalyst. Good results were also obtained in the palladium-catalyzed asymmetric alkylation of 1,3-diphenylallylic systems (up to 94% ee).

Stereoselective substitution of α-aminoalkylferrocenes with diorganozincs. A fast synthesis of new chiral FERRIPHOS ligands for asymmetric catalysis

Abstract A direct stereoselective substitution of α-aminoalkylferrocenes of type 3 with organozinc reagents provides chiral ferrocenes which can be converted to the FERRIPHOS ligands of type 1 in a one-pot procedure. These FERRIPHOS ligands have been used for the Rh-catalyzed asymmetric hydrogenation of an enol acetate with 94.9% ee .

Synthesis of α,β-disubstituted ferrocenes via a ferrocenylepoxide intermediate. Preparation and catalytic activity of a new chiral ferrocenyloxazoline

Abstract A short synthesis of the chiral oxazoline 10 (>95% e.e.) in six steps from chloroacetylferrocene is described. The ligand can be used successfully in an asymmetric Pd(0)-catalyzed allylic alkylation reaction.

Preparation of new chiral borane‐protected P,N‐ferrocenyl ligands via a methoxy directed ortho‐lithiation

We have shown that the readily prepared (ferrocenyl)benzylic methyl ethers of type 1 can be ortho-metalated with tert-BuLi with high diastereoselectivity. This reaction has been used to prepare new borane-protected P,N-substituted ferrocenes of type 2 in high diastereomeric and enantiomeric purity. The chiral heterocyclic aminophosphines 2 may be of interest as chelating ligands for asymmetric metal catalysis.

Facile axial chirality control by using a precursor with central chirality. Application to the preparation of new axially chiral diphosphine complexes for asymmetric catalysis

A diastereoselective synthesis of a new chiral diphosphine with planar chirality is performed in 2 steps from (S)-p-tolylferrocenyl sulfoxide with 60% overall yield. The ligand gives enantioselectivities up to 98% ee in Pd(0)-catalyzed allylic substitution reactions.

Preparation of a rigid bicyclic diphosphine by radical cyclisation

Abstract Bromodiphosphine oxide 3 was obtained from the selectively protected chiral diol 2 by the double [2,3]-sigmatropic shift of an intermediate phosphinite. The bromophosphine oxide derivative 3 was converted by radical cyclisation into rigid bicyclic diphosphine 1 . The diphosphine 1 was characterised and tested as a ligand in several metal catalytic reactions.