Synthesis and C-alkylation of hindered aldehyde enamines.

A new reactivity mode of hindered lithium amides with terminal epoxides is described whereby aldehyde enamines are produced via a previously unrecognized reaction pathway. Some of these aldehyde enamines display unprecedented C-alkylation reactivity toward unactivated primary and secondary alkyl halides. For comparison, the reactivity of aldehyde enamines synthesized via a traditional condensation method was examined. C- rather than N-alkylation was the dominant reaction pathway found with a range of electrophiles, making this route to alpha-alkylated aldehydes more synthetically useful than previously reported.

Substituted epoxides by lithiation of terminal epoxides.

Diamine-ligand-assisted direct hydrogen-lithium exchange allows the generation of nonstabilized (H-substituted) oxiranyllithium species and their subsequent trapping by Bu(3)SnCl and carbonyl-based electrophiles. This reaction provides a new concise route to alpha,beta-epoxystannanes and substituted epoxides.

Deprotonation-electrophile trapping of terminal epoxides.

Organolithium-induced deprotonation of terminal epoxides in the presence of appropriate diamine ligands allows trapping with a range of electrophiles, yielding functionalised di- and tri-substituted epoxides in good yields and with control of stereochemistry at the epoxide.