Science of Synthesis Knowledge Updates 2012 Vol. 1

Kurztext / Annotation

The Science of Synthesis Editorial Board,together with the volume editors and authors, is constantly reviewing the whole field of synthetic organic chemistry as presented in Science of Synthesis and evaluating significant developments in synthetic methodology. Four annual volumes updating content across all categories ensure that youalways have access to state-of-the-art synthetic methodology.

Content of this volume: Organometallic Complexes of Titanium, Silicon Compounds, Disilenes, Lithium Compounds, 1,4-Dioxins and Benzo- and Dibenzo-Fused Derivatives, 1,2-Dithiins, Seven-Membered Hetarenes with One Heteroatom, Oxepins, Benzoxepins, Azepines, Cyclopentazepines, and Phosphorus Analogues, Three Carbon-Heteroatom Bonds: Nitriles, Isocyanides, and Derivatives, Heteroatom Analogues of Aldehydes and Ketones.

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Abstracts
2.10.19 Organometallic Complexes of Titanium (Update 1)

P. Bertus, F. Boeda, and M. S. M. Pearson-Long

This chapter is an update to the earlier Science of Synthesis contribution describing the synthesis and application of titanium complexes in organic synthesis. This update focuses on the synthesis of cyclopropane derivatives using titanium reagents, with particular emphasis on the preparation of cyclopropanols from carboxylic esters (Kulinkovich reaction) and cyclopropylamines from carboxylic amides or nitriles.

Keywords: amides · bicyclic compounds · carbonates · cyclopropanes · cyclopropanols · cyclopropylamines · esters · Grignard reagents · imides · magnesium · nitriles · titanium

4.4.1 Product Subclass 1: Disilenes

A. Meltzer and D. Scheschkewitz

The syntheses of stable and marginally stable compounds with Si=Si bonds, i.e. linear and cyclic disilenes as well as tetrasilabutadienes, are reviewed. Typical procedures are described including detailed special requirements and precautions.

Keywords: alkene analogues · coupling reactions · cyclic compounds · dehalogenation · disilenes · disilenides · disilynes · photolysis · reductive coupling · silanes · silicon compounds · silylenes · silyl halides · unsaturated compounds

8.1.31 Functionalized Organolithiums by Ring Opening of Heterocycles

M. Yus and F. Foubelo

This manuscript describes the preparation of functionalized organolithium compounds by reductive opening of heterocycles and further reaction of these intermediates with electrophiles.

Keywords: activation of C-O bonds · alkali metal compounds · carbanions · carbon-metal bonds · heterocycles · lithiation · lithium compounds · radical ions · reductive cleavage

8.1.32 Syntheses Mediated by _-Lithiated Epoxides and Aziridines

L. Degennaro, F. M. Perna, and S. Florio

Three-membered ring heterocycles such as epoxides and aziridines, whose structural motif occurs frequently in natural products and biologically active substances, are an uncommon combination of reactivity, synthetic flexibility, and atom economy. Readily accessible, also in enantioenriched form, they are mainly used as electrophiles, undergoing highly regioselective ring-opening reactions when reacted with nucleophiles. There are, however, many other less conventional but useful reactions these small-ring heterocycles may undergo. This chapter surveys a selection of the most recent advances in the chemistry of _-lithiated epoxides and aziridines, which can be simply generated by treatment of the parent epoxide or aziridine with strong bases such as organolithiums or lithium amides. Such lithiated species are relatively stable and can be captured with a number of electrophiles to give more functionalized oxiranes and aziridines or undergo other transformations including 1,2-organo shifts to enolates, eliminative dimerization, beta-elimination, intramolecular cyclopropanation onto a double bond (C=C insertion), transannular C-H insertion, and reductive alkylation.

Keywords: oxiranes · aziridines · small-ring heterocycles · _-lithiation · carbenoids · organolithiums · configurational stability · asymmetric synthesis

8.1.33 Transition-Metal-Catalyzed Carbon-Carbon Bond Formation with Organolithiums

G. Manolikakes

Transition-metal-catalyzed reactions with organolithiums are a useful tool for the formation of carbon-carbon bonds. This chapter covers reactions with organolithium compounds catalyzed by various transition metals such as copper, palladium, or iron.

Keywords: lithium compounds · cross coupling · copper catalysis · palladium catalysis · iron catalysis · carbolithiation · asymmetric catalysis<

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