Enantiomerically Pure [2.2]Paracyclophane-4-thiol: A Planar Chiral Sulfur-Based Building Block Readily Available by Resolution with an Amino Acid Chiral Auxiliary

Acyl chloride of N-phthaloyl-(S)-isoleucine is an efficient chiral auxiliary for the resolution of (+/-)-[2.2]paracyclophane-4-thiol. A preparative protocol, based on the conversion into diastereoisomeric thiolesters and separation by two fractional crystallizations and column chromatography, was developed. Deprotection with LiAlH4 allowed isolation of the individual thiol enantiomers in good yield (similar to 40%) and high enantiomeric purity (ee >93%). The absolute configurations were determined by comparison of the optical rotation value of the products with literature data and were confirmed by X-ray crystallography

tert-Butyl 6-bromo-1,4-dimethyl-9H-carbazole-9-carboxyl­ate

The title compound, C19H20BrNO2, consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7) and 4.86 (7)° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7). The crystal structure is determined mainly by intra­molecular C—H⋯O and inter­molecular π–π inter­actions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-but­oxy­carbonyl group on the carbazole N atom and the intra­molecular hydrogen bond induce a particular conformation of the exocyclic N—C bond within the mol­ecule

An inter­molecular dative B←N bond in 5-(4,4,5,5-tetra­methyl-1,3,2-dioxa­borolan-2-yl)-1,3-thia­zole

The title compound, C9H14BNO2S, is in an unusual bend conformation and the B atom of one mol­ecule within the crystal forms an inter­molecular dative bond with the N atom of a neighbouring mol­ecule, an infrequent phenomenon in boronic derivative crystals

Sulfinate-mediated [3+2] cycloaddition of allenyl sulfones with activated imines to afford 3-pyrroline derivatives

International audienc

Sulfinate-mediated [3+2] cycloaddition of allenyl sulfones with activated imines to afford 3-pyrroline derivatives

International audienc

3-Pyrroline derivatives by sulfinate-triggered [3+2] cycloaddition of allenyl sulfones with activated imines

International audienc

3-Pyrroline derivatives by sulfinate-triggered [3+2] cycloaddition of allenyl sulfones with activated imines

International audienc

Hetero-Diels-Alder reactions of new sulfonylsulfines generated from α-substituted methylsulfones

Dedicated to Professor Heinz Heimgartner on the occasion of his 70 th birthday Hetero-Diels-Alder reaction with sulfines generated in situ from methylsulfones 5a-e substituted in α-position with a phosphonyl, carboxyl, carboxyoxazolidinyl, pyridyl, or a quinolyl substituent, respectively, led to new highly functionalized thiopyrans cycloadducts. When in the substrates (i.e. 5a-c) the sulfonyl group and the second substituent on the methylene carbon have comparable electronwithdrawing effect, a mixture of cis and trans isomers of the corresponding cycloadducts is obtained with low to moderate selectivities. In the case of substrates 5d and 5e, due to the strong electronwithdrawing effect of the sulfonyl compared to the pyridyl or quinolyl groups, a single isomer is obtained for cycloadducts 7d and 7e. The stereochemical arrangements in the two cycloadducts resulting from 5b and 5d (carboxylate and pyridine derivatives) have been determined by single-crystal X-ray analysis and showed that the trans isomer was favored in both cases. Keywords: thia-Diels-Alder reaction, sulfones, sulfines, thiopyran S-oxid

Organocatalysis in Electron-deficient Allene Chemistry: Sulfinate-mediated Reaction to Construct Chiral Alkynyl Products

International audienc

Chiral Alkynyl Products by a Sulfinate-mediated Approach with Allenyl Sulfones: a Modified Padwa Reaction

International audienc