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The reaction of 3,4-di-tert-butylthiophene (6a) with N-[(p-tolylsulfonyl)imino]-phenyliodinane (TsN=IPh) in the presence of Cu(MeCN)4PF6 in MeCN at room temperature provided 3,4-di-tert-butyl-1-[(p-tolylsulfonyl)imino]-1,1-dihydrothiophene (3b),3,4-di-tert-butyl-1,1-bis[(p-tolylsulfonyl)imino]-1,1-dihydrothiophene (5a), and 1-(p-tolylsulfonyl)-3,4-di-tert-butylpyrrole (7a) as the principal products. The use of 20 molar amounts of 6a gave 3b in an increased yield of 61%. Treatment of 3,4-di-tert-butylthiophene 1-oxide (1a) with (CF3CO)2O or (CF3SO2)2O, followed by reactions with RSO2NH2, ROC(=O)NH2, or RCONH2, furnished a series of S-imino derivatives (3b,c,e–h) of 6a, which carry an electron-withdrawing substituent on the imino nitrogen atom. Treatment of the S-imino derivative 3f (substituent on the nitrogen atom = COBu) with CF3CO2H gave an aminosulfonium salt (13), whose deprotonation led to the parent N-unsubstituted 1-imide derivative (3n). Treatment of 2,4-di-tert-butylthiophene 1-oxide (1b) with TsN=IPh in the presence of Cu(MeCN)4PF6 in MeCN at room temperature provided 2,4-di-tert-butyl-1-[(p-toluenesulfonyl)imino]-1,1-dihydrothiophene 1-oxide (4e) in 81% yield. Hydrolysis of 4e by concentrated H2SO4 at room temperature furnished 2,4-di-tert-butyl-1-imino-1,1-dihydrothiophene 1-oxide (4f) in 89% yield. A pair of enantiomers of 4f were separated by high-performance liquid chromatography (HPLC) on a chiral column, and their absolute configurations were determined by an X-ray crystallographic analysis. Structures of sulfilimine, sulfone diimine, and sulfoximine derivatives of monocyclic thiophenes, obtained in these ways, are discussed based on spectroscopies (IR and 1H and 13C NMR) and X-ray crystallographic analyses. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:333–348, 2001

We have developed chiral Schiff base catalysts based on the ONO-tridentate ligand for the catalytic enantioselective addition of dialkylzinc to aldehydes. Various aldehydes were smoothly converted into corresponding optically active secondary alcohols with high enantioselectivity (up to 98 % ee) in high yield. Furthermore, we have succeeded in decreasing the catalyst loading minimum to 0.1 mol % in the chiral Schiff base-catalyzed enantioselective alkylation of aldehydes.

A variety of benzylic alcohols were oxidized to the corresponding carbonyl compounds selectively in the presence of activated carbon under molecular oxygen atmosphere. This process does not require...