25674-48-0Relevant academic research and scientific papers
A study of enantioselective syntheses by Sharpless asymmetric oxidation for aryl sulfoxides containing oxygen groups at the ortho position
Takei, Takanori,Takayama, Jun,Xuan, Meiyan,Tomoda, Misa,Miyamae, Hiroshi,Sakamoto, Takeshi
, (2021/03/16)
Abstract: While ortho-alkoxy aryl sulfoxides including various substituents were synthesized by Sharpless asymmetric oxidation reaction, we optimized the reaction conditions and screened better combination of starting materials to obtain high enantioselectivity. The result suggested new information that electron-withdrawing substituents on the aromatic ring have a strong influence upon enantioselectivity of the products. Also, several chiral ligands for Sharpless asymmetric oxidation reaction were evaluated to improve the enantioselectivity. Graphic abstract: High enantioselectivity of ortho-alkoxy aryl chiral sulfoxides have been achieved by Sharpless oxidation reaction using Ti(O-i-Pr)4 and diethyl tartrate under anhydrous condition. In particular, the enantioselctivity of products was influenced by electron-withdrawing substituents on the aromatic ring, such as nitro, ester and aldehyde groups.[Figure not available: see fulltext.]
METALATION REACTIONS. XIV. REGIOSPECIFIC PREPARATION OF POLYSUBSTITUTED BENZENES VIA MONO- OR DI-LITHIATION REACTIONS OF AROMATIC THIOETHERS
Cabiddu, Salvatore,Fattuoni, Claudia,Floris, Costantino,Gelli, Gioanna,Melis, Stefana,Sotgiu, Francesca
, p. 861 - 884 (2007/10/02)
The preparation of polyfunctionalized aromatic thioethers either by one-step dilithiation or by two successive one-flask monometalation reactions is described.By acting on 1 two equal or different electrophiles one on the thiomethyl group and one in the ortho-position with respect to it are introduced; by acting on 11 and on 35 the substitution involves the thiomethyl carbon atom and that in the ortho-position with respect to the alkoxy group.In the case of the homologeous isopropylthio (23) the substitution involves the two aryl carbon atoms in the ortho-position to both functions.In the case of the p-disubstituted isomers (49, 59) analogous behaviour to ortho isomers in one-step metalation reaction is observed, while the two hydrogen atoms in the ortho-positions to the methoxy group are substituted when two successive monometalations are employed.The metalation of 40 results low selective.The behaviour of 79 and 93 is analogous to 1, while 72, 88 and 96 undergo only one-step monometalation reactions.
