Mariola Zielińska-Błajet

Simple preparation of enantiomeric Michael adducts of thiophenol to chalcones: easily available new chiral building blocks

Abstract A facile and enantioselective method for the multigram preparation of the title compounds is described. The Michael addition of thiophenols to chalcones catalyzed by (+)-cinchonine, followed by crystallization, led to the corresponding adducts 2 in up to >95% e.e. The stereoselective Beckmann rearrangement of the oxime of (+)-1,3-diphenyl-3-phenylsulfanylpropan-1-one 2a gives the anilide of (R)-(+)-3-phenyl-3-phenylsulfanylpropanoic acid (as determined by X-ray analysis) and alcoholysis leads to the corresponding enantiomerically pure ethyl ester.

A new and efficient route to homochiral γ-hydroxysulfoxides and γ-hydroxysulfones

Abstract Readily available (+)-( R )-1,3-diphenyl-3-phenylsulfanyl-propan-1-one 1 was oxidized to the corresponding sulfone and its reduction gave separable (1 R ,3 R )- and (1 S ,3 R )-1,3-diphenyl-3-phenylsulfonylpropan-1-ols. When 1 was reduced to the mixture of epimeric alcohols, subsequent reaction with three different sulfoxidation agents allowed the separation of all four diastereomeric 1,3-diphenyl-3-phenylsulfinylpropan-1-ols in diastereomerically pure form. The absolute configuration at the newly created stereogenic carbon was proved by chemical correlation, while the configuration of the sulfur centre of the phenylsulfinyl group was established by CD spectroscopy.

Substituted N -salicylidene β-aminoalcohols: preparation and use as chiral ligands in enantioselective sulfoxidation and conjugate addition

A high yielding synthesis of optically active 3,5-disubstituted salicylidene β-amino alcohols (6) is described. The catalytic use of D or L-N-(3-phenyl-5-nitrosalicylidene)valinol in enantioselective sulfoxidation (H2O2 / VO(acac)2) gives up to 95% e.e. Asymmetric conjugate addition of thiophenol to 2-cyclohexen-1-one catalysed by Ti(OPr-i)4 and 6 leads to maximum 31% e.e. in the product.

Cyclization of 1,3-diaryl-3-phenylsulfanyl-1-propanols to thiochromans with the participation of [1,3]-PhS shift

Abstract Optically active (3R,1RS)-3-aryl-1-phenyl-3-phenylsulfanyl-1-propanols were easily dehydrated forming mainly rac-cis-2-aryl-4-phenylthiochroman, and rac-cis-4-aryl-2-phenylthiochroman along with the corresponding trans-isomers. The observed reaction outcome (rearrangement and racemisation) apparently results from the SEAr reaction involving the unusual 1,3-phenylsulfanyl group migration. This interpretation is supported by the results of theoretical studies (DFT) on the supposed intermediates.

New diphenyl diselenides o-substituted by an O(S,Se)-caranyl skeleton – synthesis and application in asymmetric reactions

An efficient methodology for the synthesis of diphenyl diselenides o-substituted by O(S,Se)-caranyl moieties has been presented. 4-Caranyl and 4-isocaranyl groups have been connected to the phenyl ring by an oxygen, sulfur or selenium atom. The influence of the selenium–heteroatom interactions on the diastereoselectivity of the methoxyselenenylation of styrene has been evaluated. The best result was obtained for diselenide with an O-caranyl group substituted in the ortho-position. X-ray crystal structure of this compound was determined and the observed intramolecular interactions were discussed. Additionally diselenides bearing a sulfur atom were transformed to the corresponding methyl o-(S-caranyl) and o-(S-isocaranyl)-substituted phenyl selenides, and were tested as catalysts in the Tsuji–Trost allylic alkylation and Henry reaction.

Stereoselective Dithiophosphorylation of Cinchona Alkaloids: Easy Approach to Prospective Chiral Ligands and Organocatalysts

Abstract The 9-mesylates of Cinchona alkaloids reacted with HSP(S)(OEt)2 in benzene at 50°C to give the corresponding O,O-diethyl-dithiophosphates of the alkaloids with complete inversion of configuration at the 9-C stereogenic centers (3 examples, 42–45% yields). Also O-ethyl-dithiophosphoric acid derivative of 9-epi-quinine was obtained. The configuration of the stereogenic centers were established using homo- and hetero-NOE NMR techniques and comparing the experimental and calculated (GIAO/DFT) spectra. The dithiophosphates of alkaloids were tested as chiral ligands in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenylprop-2-enyl acetate and in the Cu-catalyzed asymmetric Henry reaction and gave the respective product with up to 51% ee. Quinine O,O-diethyl-phosphorodithioate was also tested as a novel potential chiral solvating agent for amino acids (N-Boc-phenylglycine) in 31P and 1H NMR spectroscopy. [Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental files: Additional figures] GRAPHICAL ABSTRACT