Lithium enolates oxirane ring opening

SCHEME 9 Synthesis of (—)-deoxocassine (2) using ntramolecular reductive animation via oxirane ring opening by the nucleophilic lithium aza-enolate. 

Oxirane ring opening reaction with a nucleophile mediated by alkali metal salts has been studied extensively. Several oxiranes react with ammonium halide [51], KCN [52], NaNs [53], lithium acetylide [54], amines [55], and ketone enolate [56] in the presence of alkali metal salts providing corresponding -functionalized alcohols. 

To effect P-eliminative oxirane ring openings, lithium dialkylamides are a safer bet than alkyllithiums as the latter may metalate an oxygen-adjacent position instead. The medium-sized six- to ten-membered epoxycycloalkanes are particularly prone to a-metalation and subsequent enolate (after neutralization, cycloalkanone) formation and, on the other hand, insertion into transannular C-H bonds. ... 

Crotti and co-workers extensively studied the ring-opening functionalization of oxi-ranes using a variety of alkali-metal salts. Several oxiranes were reacted with ammonium halides [119], KCN [120], NaNa [121], lithium acetyhde [122], amines [123], and ketone enolates [124] in the presence of alkali-metal salts to afford the formation of the corresponding 8-functionalized alcohols and some of the results are listed in Table 1. 

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