Joyce Takahashi Doi

SYNTHESIS AND STRUCTURE OF THE MESOCYCLIC COMPOUNDS, 5-PHENYL-l-THIA-5-PHOSPHACYCLOOCTANE, CIS- AND TRANS-1,5-DIPHENYL-1,5-DIPHOSPHACYCLOOCTANE AND THEIR PHOSPHINE OXIDES

Three 1.5-disubstituted eight-membered ring meSocycles, 5-phenyl-l-thia-5-phosphacyclooctane, 2, cis-and trans-1,5-diphenyl-1,5-diphosphacyclooctane. 5a and 5b, have been synthesized. The diastereomers 5a and 5b were separated by preparative HPLC and the stereochemical assignments confirmed by an X-ray crystal structure of 5b. The X-ray crystal structures of 5-phenyl-1-thia-5-phosphacyclooctane 5-oxide, 1, and trans-l,5-diphenyl-l,5-diphosphacyclooctane 1.5-dioxide, 3b, are also reported. MeSocycles 1, 3b and 5b are in the boat-chair conformation and are devoid of any indications of transannular interactions.

Thioether protection via selectively cleavable sulfonium salts

Abstract There are few protecting groups available for the thioether functionality. The selective cleavage of 4-phthalimidobutyl- and p -methoxybenzylsulfonium salts make these derivatives ideal for thioether protection.

Anchimerically assisted redox reactions : Comparisons of the effect of transannular - OH and -NH2 group son the rate of the aqueous I2 oxidation of thioethers. Structures of the heteroatom bridged l-thioniabicyclo[3.3.1]nonane intermediates

Abstract The rate law for the aqueous I 2 oxidation of 5-amino-1-thiacyclooctane has been determined and compared with 5-hydroxy-l-thiacyclooctane. The crystal structures of the 9-aza- and 9-oxa-l-thioniabicyclo[3.3.1]nonanes formed on oxidative cyclization are compared.

The aqueous periodate oxidation of aromatic and aliphatic carboxylic acid disulfides

Abstract The water-soluble carboxylic acid-functionalized aromatic disulfides, 3,3′-dithiodibenzoic acid and 5,5′-dithiodiisophthalic acid (5,5′-dithiodi(1,3-benzenedicarboxylic acid)) were prepared and their rates of periodate oxidation to the sulfonic acids were determined. The reaction is first order in each of the reactants which indicates that the slow step is the initial oxidative cleavage step. These aromatic disulfides are oxidized to the sulfonic acids 4–8 times more slowly than a typical aliphatic disulfide. In all cases, water solubility of the disulfide is of prime importance. The periodate oxidation of two aliphatic carboxylic acid analogs were also examined, however, in these cases, the reactions were multiphasic and intermediate thiosulfinates were observed by 1H NMR along with the sulfonic acids.

NEIGHBORING GROUP PARTICIPATION IN ORGANIC REDOX REACTIONS. 13. INTRAMOLECULAR INTERACTION OF THE β-PHOSPHONIC ACID GROUP IN THE AQUEOUS IODINE OXIDATION OF THIOETHERS AND DISULFIDES.1 GENERATION OF A PHOSPHONIC-PHOSPHORIC ANHYDRIDE

Abstract The oxidation of the phosphonic acid-thioether, 2-methylthioethanephosphonic acid (MTEP) and the oxidative-cleavage of the phosphonic acid-disulfide (PED) by aqueous iodine are accelerated by neighboring-group participation. The pH profiles indicate that in both cases it is the dianionic form of the phosphonate group which is responsible for accelerations of 106 and 102 in the reactions of MTEP and PED. respectively, compared to analogs without neighboring groups. The oxidative cleavage of PED in the presence of phosphate buffer generates ca. 30% of a hydrolytically stable, mixed phosphonic-phosphoric anhydride, which makes the proposed cyclic sulfenic-phosphonic anhydride intermediate one of the more efficient phosphate-coupling agents in aqueous solution. In contrast, no mixed anhydride is generated during the oxidation of MTEP in phosphate buffer.