ASYMMETRIC-SYNTHESIS AND PROPERTIES OF SULFINIMINES (THIOOXIME S-OXIDES)

Enantiomerically pure sulfinimines (thiooxime S-oxides 10), important building blocks in the asymmetric synthesis of amine derivatives, are prepared in good to excellent yields in one step from aromatic, hetero aromatic, and aliphatic aldehydes. This protocol involves treating com mercially available (R)-or (S)-menthyl p-toluenesufinate (Andersen rea gent 4) with LiHMDS, followed by the aldehyde, affording (E)-10 exclus ively. The sulfinimines 10 are formed via a Peterson-type olefination reaction of silylsulfinamide anion 13 with the aldehyde. Anion 13 is g enerated by reaction of lithium menthoxide (12a) with bis(trimethylsil yl)sulfinamide 11, which is formed in the reaction of 4 with LiHMDS. T he other product formed is O-(trimethylsilyl)menthol (12c), which is i solated in >80% yield for recycling. Two other less efficient methods for the asymmetric synthesis of 10 are discussed: (i) the asymmetric o xidation of sulfenimines 6 with chiral nonracemic oxaziridines and (ii ) the reaction of metal aldimines, prepared from nitriles, with 4. All of these protocols fail with ketones.