ortho-Lithiation of S-tert-butyl-S-phenylsulfoximines. New route to enantiopure sulfinamides via a de-tert-butylation reaction
摘要:
The sulfoximine group proved to be an excellent ortho-directing group in lithiation reactions. Several electrophiles were used to afford the corresponding ortho-functionalized aryl sulfoximines in good yields. The use of prochiral electrophiles lead to modest to good diastereoselectivities up to 95%. During this study, we observed a side reaction due to a S-de-tert-butylation. After optimization of this S-de-tert-butylation reaction, the corresponding enantiopure sulfinamides could be obtained in good yields. (c) 2005 Elsevier Ltd. All rights reserved.
Sulfoximines: A Reusable Directing Group for Chemo- and Regioselective ortho CH Oxidation of Arenes
作者:M. Ramu Yadav、Raja K. Rit、Akhila K. Sahoo
DOI:10.1002/chem.201200092
日期:2012.4.27
Sulfoximinesdirect: A new protocol for the chemo‐ and regioselectiveorthoCH acetoxylation of arenes in N‐benzoylated sulfoximines is reported. The sulfoximinedirectinggroup is easily detached from the CHoxidation product through acid‐promoted hydrolysis, isolated, and reused (see scheme). The meta‐substituted phenols are synthesized following this strategy and the stereointegrity of the sulfoximine
The readily available S-(tert-butyl)-N-(trimethylsilyl)-S-phenylsulfoximine was prepared from S-methyl-N(trimethylsilyl)-S-phenylsulfoximine via lithiation-methylation sequences. The reaction with n-butyllithium in THF at -78 degrees C afforded the corresponding ortho-lithiated species which could be trapped with different electrophiles in good yields. Addition of benzaldehyde proceeded with a modest diastereoselectivity (de=52%). (C) 1999 Published by Elsevier Science Ltd. All rights reserved.