176956-93-7Relevant academic research and scientific papers
A study of factors affecting enantioselectivity in the oxidation of aryl benzyl sulfides in the presence of chiral titanium catalysts
Capozzi, Maria Annunziata M.,Centrone, Caterina,Fracchiolla, Giuseppe,Naso, Francesco,Cardellicchio, Cosimo
scheme or table, p. 4327 - 4334 (2011/09/16)
A series of experiments was performed to test a theoretical model that we have recently proposed to explain the highly enantioselective oxidation of aryl benzyl sulfides with tert-butyl hydroperoxide in the presence of a complex between titanium and (S,S)
Systematic investigation of CD spectra of aryl benzyl sulfoxides interpreted by means of TDDFT calculations
Pescitelli, Gennaro,Di Pietro, Sebastiano,Cardellicchio, Cosimo,Capozzi, Maria Annunziata M.,Di Bari, Lorenzo
experimental part, p. 1143 - 1154 (2010/04/02)
(Chemical Equation Presented) The CD spectra of 13 crystalline aryl benzyl sulfoxides 1a-m with various substituents on the two aromatic rings were recorded in solution and in the solid state. Solution CD spectra were very homogeneous along the series, consisting in most cases of a couplet-like feature in the 200-300 nm region. The red-shifted component of the couplet, corresponding to the sulfoxide-centered n-π* transition, is always positive for (R) absolute configuration in accordance with Mislow?s rule. The presence of a strong electron-withdrawing substituent on the phenyl ring (nitro or ester group) alters the shape of the CD spectrum. CD calculations using the TDDFT method were run for eight representative compounds using DFT-optimized geometries. In all cases, calculated spectra were in very good agreement with experimental ones and allowed for rationalization of the diverse spectral behaviors. It is demonstrated thatTDDFT//DFTcalculations represent a reliable option for assigning the absolute configuration of this class of compounds whenever crystals suitable for X-ray are not available. Solid-state CD spectra recorded with the KCl pellet technique were in some cases in agreement with those in solution. However, in other cases new and strongCD signals appeared which were interpreted as being due to intermolecular couplings in the crystals.
Enantioselective sulfoxidation and kinetic resolution combined protocol mediated by a functionalized (S)-norcamphor-based hydroperoxide/titanium(IV) isopropoxide system
Lattanzi, Alessandra,Piccirillo, Sandro,Scettri, Arrigo
, p. 357 - 363 (2008/02/07)
A functionalized tertiary furyl hydroperoxide derived from (S)-norcamphor has been easily synthesized in good yield and in a highly diastereoselective manner. Good to high enantioselectivities (up to 99% ee) and acceptable to good yields (up to 86%) were achieved for the sulfoxides, by tandem stereoconvergent asymmetric sulfoxidation and kinetic resolution when using the novel hydroperoxide s oxygen donor and chirality source in the presence of catalytic loadings of titanium(IV) isopropoxide as the catalyst.
A straightforward enantioselective route to dialkyl sulfoxides based upon two carbon-for-carbon substitution reactions on the sulfinyl group
Capozzi, Maria Annunziata M.,Cardellicchio, Cosimo,Naso, Francesco,Rosito, Valerio
, p. 7289 - 7294 (2007/10/03)
Benzyl p-bromophenyl sulfoxide 1 was obtained on a multigram scale and in an enantiomerically pure form by an enantioselective catalytic oxidation, using tert-butyl hydroperoxide in the presence of chiral titanium complexes. Some mechanistic and stereochemical features of interest were studied in this process. Compound 1 was then subjected to two different substitution reactions with Grignard reagents, which caused two sequentially stereocontrolled carbon-for-carbon displacements, leading to chiral nonracemic dialkyl sulfoxides.
