Reaction of tertiary cyclopropyl silyl ethers with diethylaminosulfur trifluoride: the effects of substituents on the cleavage of the cyclopropane ring

DAST-mediated ring-opening of cyclopropyl silyl ethers in nitriles: facile synthesis of allylic amides via a Ritter-type process

A diethylaminosulfur trifluoride (DAST)-mediated ring-opening reaction of cyclopropyl silyl ethers in nitriles produced allylic amides in moderate to good yields (up to 87%). Time course studies using ReactIR and O-isotopic labeling mechanistic studies suggested that the present reaction occurs via a Ritter-type process, leading to the formation of allylic amides.

Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes: scope and limitations

Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes utilizing S-monofluoromethyl-S-phenyl-2,3,4,5-tetramethylphenylsulfonium tetrafluoroborate is an efficient approach to obtain a range of monofluorocyclopropane derivatives. So far, fluoromethylsulfonium salts have displayed the broadest scope for direct fluoromethylene transfer. In contrast to more commonly used fluorohalomethanes or freon derivatives, diarylfluoromethylsulfonium salts are bench stable, easy-to use reagents useful for the direct transfer of a fluoromethylene group to alkenes giving access to the challenging products - fluorocyclopropane derivatives. Interplay between the reactivity of the starting materials and stability of the fluorocyclopropanes formed determines the outcome of the process.

Diastereoselective Monofluorocyclopropanation Using Fluoromethylsulfonium Salts

Diarylfluoromethylsulfonium salts, alternatives to freons or advanced fluorinated building blocks, are bench stable and easy-to-use sources of direct fluoromethylene (:CHF) transfer to alkenes. These salts enabled development of a trans-selective monofluorinated Johnson-Corey-Chaykovsky reaction with vinyl sulfones or vinyl sulfonamides to access synthetically challenging monofluorocyclopropane scaffolds. The described method offers rapid access to monofluorinated cyclopropane building blocks with further functionalization opportunities to deliver more complex synthetic targets diastereoselectively.

Catalytic asymmetric Simmons-Smith cyclopropanation of silyl enol ethers. Efficient synthesis of optically active cyclopropanol derivatives

[reaction: see text] This paper describes a catalytic asymmetric Simmons-Smith cyclopropanation of silyl enol ethers using dipeptide 2 as the ligand. A variety of optically active cyclopropyl silyl ethers can be obtained in high yields. Up to 96% ee was obtained. The dipeptide can be recovered after the reaction in good yield and reused without the loss of reactivity or enantioselectivity.