Cyclization Reactions of 1,3-Bis-Silyl Enol Ethers and Related Masked Dianions

Despite their simplicity and synthetic usefulness, reactions of 1.3-dicarbonyl dianions are often problematic, since they represent highly reactive compounds (low reactivity matching). In addition, functionalized electrophiles are often rather labile and reactions with strong nucleophiles can result in polymerisation, decomposition, formation of open-chain products, elimination, or SET-reactions. These intrinsic limitations can be overcome by the use of 1,3-bis-silyl enol ethers, electroneutral 1,3-dicarbonyl dianion equivalents, in Lewis acid catalyzed reactions. 1 Synthesis and Rearrangements of 1,3-Bis-Silyl Enol Ethers 2 Aldehydes and Ketones 3 Acetals 4 1,2-Dicarbonyl Derivatives 5 1,3-Dicarbonyl Derivatives 6 Orthoesters 7 1,4-Dicarbonyl Derivatives 8 Carboxylic Acid Derivatives 9 Oxalyl Chloride 10 Epoxides 11 Michael Reactions 12 [4+2] Cycloadditions 13 SET Reactions