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, heteroaromatic, and aliphatic aldehydes. This protocol involves treating commercially available (R)- or (S)-menthyl p-toluenesufinate (Andersen reagent 4) with LiHMDS, followed by the aldehyde, affording (E)-10 exclusively. The sulfinimines 10 are formed via a Peterson-type olefination reaction of silylsulfinamide anion 13 with the aldehyde. Anion 13 is generated by reaction of lithium menthoxide (12a) with bis(trimethylsilyl)sulfinamide 11, which is formed in the reaction of 4 with LiHMDS. The other product formed is O-(trimethylsilyl)menthol (12c), which is isolated in >80% yield for recycling. Two other less efficient methods for the asymmetric synthesis of 10 are discussed: (i) the asymmetric oxidation 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.
Davis
Franklin A.
FA
Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Reddy
Rajarathnam E.
RE
Szewczyk
Joanna M.
JM
Reddy
G. Venkat
GV
Portonovo
Padma S.
PS
Zhang
Huiming
H
Fanelli
Dean
D
Thimma Reddy
R.
R
Zhou
Ping
P
Carroll
Patrick J.
PJ