Intramolecular Addition Reactions of Allylic and Propargylic Silanes

The regio- and stereoselectivities in the intramolecular addition of allyl- and propargylsilane moieties to acceptor groups (ketones, enones and dienones), are reviewed. Emphasis is placed on the synthetic scope and applications to the total synthesis of natural products. 1. General Considerations 2. Fluoride Ion Versus Lewis Acids 3. Sakurai Reactions (1,4-Additions) 4. Intramolecular Sakurai Reactions 4.1. Spiro Cyclizations with Allylic Silanes 4.2. Spiro Cyclizations with Propargylic Silanes 4.3. Annelation Reactions: Synthesis of Functionalized Bicyclo- [4.3.0]nonan-3-ones with Allylic Silanes 4.4. Annelation Reactions: Synthesis of Functionalized Bicyclo- [4.3.0]nonan-3-ones with Propargylic Silanes 4.5. Annelation Reactions: Ring-Size Selectivity Governed by the Silyl Side Chain 4.6. Annelation Reactions: Ring-Size Selectivity Governed by the Lewis Acid 5. Additions to N-Acyliminium Ions Derived from Lactams 6. Applications to the Total Synthesis of Natural Products 6.1. Stereoselective Syntheses of Nootkatone and Valencene 6.2. Stereoselective Synthesis of Perforenone 6.3. Stereoselective Syntheses of Isoretronecanol and Epilupinine 6.4. Regioselective Synthesis of Gabaculine 7. Conclusions