Studies on organic fluorine compounds. LIII. Preparation of functionalized trifluoromethylated compounds using 1-phenylsulfonyl-3,3,3-trifluoropropene

Reaction of 1-phenylsulfonul-3,3,3-trifluoropropene(1) with carbonyl-stabilized enolate anions smoothly proceeded to give the addition products(7) in good yield while with an alkyl-lithium or Grignard reagent the formation of the vinyl anion(8) was one of the reaction pathways. Reaction of 1 with the chiral nucleophiles(11, 16) was carried out to give the functionalized trifluoromethylated compounds(13, 7b) in 4-43% ee     

Efficient synthesis of optically active atropisomeric anilides through catalytic asymmetric N-arylation reaction

In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation of ortho-tert-butyl-NH-anilides with 4-nitroiodobenzene proceeds with high enantioselectivity (89-95% ee) to give optically active atropisomeric anilides possessing N-C chiral axis. Furthermore, the intramolecular version of the present catalytic asymmetric N-arylation gave atropisomeric lactams with high optical purity (94-96% ee).     

Stereocontrolled synthesis of 7-hydroxy- and 7-acetoxy-PGI2: New stable PGI2 analogues

Stable analogues of PGI₂, 7-hydroxy- and 7-acetoxy-PGI₂, were synthesized from protected PGI₂ methyl ester $\text{1b}$via sulfoxides $\text{6a}$, $\text{6b}$ through stereocontrolled sulfoxide-sulfenate rearrangement.     

The Synthesis of Damascenone and β-Damascone and the possible mechanism of their formation from carotenoids

A brief synthesis of damascenone ( 5 ) from the acetylenic diol 2 and also that of β-damascone ( 8 ) from β-ionol, resembling the biogenetic synthesis, are described. A possible mechanism for the formation of damascenone from neoxanthin is proposed.     

Synthesis of new crown ethers and their metal complexes: 1H and 13C NMR study

A new type of crown ethers containing a diphenyl ether unit has been prepared, the ring size ranging from 12 to 36. ¹H and ¹³C NMR spectra of both free ligands and their metal-ion complexes have been recorded. For 18- and 21-membered compounds a general downfield shift was observed for both methylene and aromatic proton resonances on metal-ion complexation. The stoichiometry of K⁺ and Na⁺ complexes was deduced from chemical shift dependence on metal-ion concentration. The K⁺ and Na⁺ complexes of 18- and 21-membered rings have a guest to host ratio of 1:1, whereas the K⁺ salt of the 15-membered ring exists as a 1:2 complex in solution. The ¹H shift observed on salt formation was attributed to electric-field and conformational effects. The ¹³C resonances for the aryl carbons, C-1, C-2 and C-3, and the α-methylene carbon in 15- and 18-membered rings were shifted upfield when an equivalent amount of KSCN was added in CDCI_3?DMSO-d₆. The shift changes were independent of the anion, and similar results were obtained for SCN^?, Br^?, and I^? salts. The upfield shift is explained by conformational factors. The spectral changes were slight for 12- and 36-membered rings. In 15- and 18-membered rings, complexation induces conformational changes which force the C-α carbon into the plane of the benzene ring. The solution conformation of these molecules is discussed.