1429933-88-9Relevant academic research and scientific papers
Synthesis of enantiomers of 3-methyl- and 3-phenyl-3,4-dihydro-2H-[1,4]benzothiazines and their 1,1-dioxides via an acylative kinetic resolution protocol
Gruzdev, Dmitry A.,Chulakov, Evgeny N.,Sadretdinova, Liliya Sh.,Kodess, Mikhail I.,Levit, Galina L.,Krasnov, Victor P.
, p. 186 - 194 (2015)
It has been found that acyl chlorides of (S)-naproxen, N-phthaloyl-(S)-leucine, and N-tosyl-(S)-proline are efficient chiral resolving agents for the acylative kinetic resolution of racemic 3-methyl- and 3-phenyl-3,4-dihydro-3-methyl-2H-[1,4]benzothiazines. Based on the experimental results, a preparative protocol comprising the acylative kinetic resolution followed by isolation of a single (major) diastereoisomeric amide and subsequent hydrolysis of amide bond was proposed. Using this approach with various chiral resolving agents, (S)- and (R)-enantiomers of 3,4-dihydro-3-methyl-2H-[1,4]benzothiazine (ee >99%) were obtained. The oxidation of the corresponding diastereoisomers of the amides followed by deacylation led to the (S)- and (R)-enantiomers of 3,4-dihydro-3-methyl-2H-[1,4]benzothiazine-1,1-dioxide (ee >97%). This method proved to be less suitable for the preparation of the (S)-enantiomer of 3,4-dihydro-3-phenyl-2H-[1,4]benzothiazine (ee up to 93%) and its sulfone (ee 82%) which were both obtained in low yields. The loss of enantioselectivity for (S)-3,4-dihydro-3-phenyl-2H-[1,4]benzothiazine and its sulfone occurred during hydrolysis of the corresponding diastereoisomerically pure amides.
Adamantyl-BINOL as platform for chiral porous polymer aromatic frameworks. Multiple applications as recyclable catalysts
Monterde, Cristina,Navarro, Rodrigo,Iglesias, Marta,Sánchez, Félix
, p. 609 - 618 (2019/08/26)
Herein, we report the synthesis of adamantyl-BINOL-based chiral porous aromatic polymers (Ad-BINOL-PAFs) for heterogeneous catalysis. Ad-BINOL-OH-PAF (365 m2·g?1 SABET) was built through the covalent bonds among of 4,4′-dibromo-O-ethyl-protected adamantyl-BINOL with 1,3,5-Triphenylbenzene-4′,4″,4′″-triboronic acid and in the presence of [Ti(OiPr)4] results an effective recyclable catalyst in the asymmetric addition of diethylzinc to aromatic aldehydes (ee up to 88%). The corresponding heterogenized phosphoric acid (Ad-BINOL-PO2H-PAF) was applied as heterogeneous recyclable organocatalyst for the cascade condensation/amine addition of anthranilamide with aldehydes and transfer hydrogenation reactions obtaining high yields but low enantioselectivity. On the other hand, heterogeneous phosphoric acid (Ad-BINOLs-PO2H-PAF) was also used as effective phosphate ligands for synthesis of rhodium(II) complexes which were effective catalysts in cyclopropanation of styrene affording chiral cyclopropanes in good yield and high diastereoselectivity (>99%) and moderate enantioselectivity (ee 50%).
