Organotitanium Reagents in Organic Synthesis

01.03.1986

Englisch

9783540157847

Springer Berlin

Reactivity and Structure: Concepts in Organic Chemistry

Nein

Manfred T. Reetz

236

Gebundene Ausgabe

24

chirality, synthesis, organic chemistry, organic synthesis, polymer

PNN - Organische Chemie

1. Introduction.- 1.1 Adjustment of Carbanion-Selectivity via Titanation.- 1.2 Other Uses of Titanium in Organic Chemistry.- References.- 2. Synthesis and Properties of Some Simple Organotitanium Compounds.- 2.1 Synthesis and Stability.- 2.1.1 Historical Aspects.- 2.1.2 Mono-Aryl- and Alkyltitanium Compounds.- 2.1.3 Polyalkyl- and Aryltitanium Compounds.- 2.1.4 h5-Cyclopentadienyltitanium(IV) Compounds.- 2.2 Bond Energies.- 2.3 Bond Angles and Lengths.- 2.4 Aggregation State.- 2.5 Spectroscopic and Theoretical Aspects.- 2.5.1 Introductory Remarks.- 2.5.2 Methyltitanium Compounds.- 2.5.3 h5-Cyclopentadienyltitanium Compounds.- 2.6 Conclusions.- References.- 3. Chemoseleetivity in Reactions of Organotitanium Reagents with Carbonyl Compounds.- 3.1 Aldehyde/Ketone Differentiation.- 3.1.1 Reagents of the Type RTi(OCHMe2)3.- 3.1.2 Organotitanium Reagents Bearing Other Ligands.- 3.1.3 Titanium Ate Complexe.- 3.2 Aldehyde/Aldehyde and Ketone/Ketone Differentiation.- 3.3 Chemo- and Regioselective Additions to ?,?-Unsaturated Carbonyl Compounds.- 3.4 Aldehyde/Ester and Ketone/Ester Differentiation.- 3.5 Reactions in the Presence of Additional Functionality.- 3.6 Addition to Enolizable Ketones.- 3.7 Limitations of Organotitanium Reagents.- 3.8 Hints on How to Use Organotitanium Compounds.- 3.9 Why Does Titanation of Carbanions Increase Chemoselectivity?.- 3.10 Comparison with Other Organometallic Reagents.- 3.11 Reversal of Chemoselectivity: Chemoselective in situ Protection of Carbonyl Compounds.- 3.12 Organotitanium Reagents from Non-Organometallic Precursors 107 References.- References.- 4. Rates of Reactions.- 4.1 Kinetics of the Addition of CH3Ti(OCHMe2)3 to Carbonyl Compounds.- 4.2 Other Kinetic Studies.- References.- 5. Stereoselectivity in the Addition of Organotitanium Reagents to Carbonyl Compounds.- 5.1 Titanation of Carbanions as a Means to Control Stereoselectivity.- 5.2 Diastereofacial Selectivity.- 5.2.1 The Cram/anti-Cram Problem.- 5.2.2 Chelation-Control in Addition Reactions of Chiral Alkoxy Carbonyl Compounds.- 5.2.2.1 1,2 Asymmetric Induction.- 5.2.2.2 1,3 and 1,4 Asymmetric Induction.- 5.2.3 Non-Chelation-Controlled Additions to ?-Chiral Alkoxy Carbonyl Compounds.- 5.3 Simple Diastereoselectivity.- 5.3.1 Titanium-Mediated Aldol Additions.- 5.3.2 Aldol-Type Additions of Titanated Heterocycles.- 5.3.3 Addition of Prochiral Allylic Titanium Reagents.- 5.3.4 Addition of Prochiral Propargyl-Titanium Reagents.- 5.4 The Problem of Equatorial vs. Axial Addition to Cyclic Ketones.- 5.5 Enantioselective Additions.- 5.5.1 Reagents with Chirally Modified Ligands at Titanium.- 5.5.2 Reagents with the Center of Chirality at Titanium.- 5.5.3 Titanation of Carbanions which Contain a Chiral Auxiliary.- References.- 6. Michael Additions.- References.- 7. Substitution Reactions.- 7.1 Titanium Enolates as Nucleophiles.- 7.2 Alkyltitanium Compounds as Nucleophiles.- 7.2.1 SN1-Active Alkyl Halides and Related Alkylating Agents.- 7.2.2 Direct Geminal Dialkylation of Ketones and Aldehydes and Exhaustive Methylation of Acid Chlorides.- 7.2.3 Acetals as Alkylating Agents.- 7.2.4 Metallated N,0-Hemiacetals as Alkylating Agents.- 7.3 Other Substitution Reactions: Present and Future.- References.- 8. Wittig-type Methylenation of Carbonyl Compounds.- References.

0 mm