Synthesis and crystal and molecular structure of the conformationally restricted methionine analog (.+-.)-2-exo-amino-6-endo-(methylthio)bicyclo[2.2.1]heptane-2-endo-carboxylic acid and neighboring group participation in its anodic oxidation

Neighboring Amide Participation in Thioether Oxidation: Relevance to Biological Oxidation

“…40 Compounds 3 and 4 were synthesized from the previously reported amino ester 5. 41 Reaction of 5 with trimethylsilyl isocyanate followed by treatment of the crude product with sodium methoxide in methanol provided hydantoin 3 in 91% yield after column chromatography. 2,5-Diketopiperazines 4 were synthesized as shown in Scheme 1.…”

“…Compounds 2a and b were synthesized as reported previously . Compounds 3 and 4 were synthesized from the previously reported amino ester 5 . Reaction of 5 with trimethylsilyl isocyanate followed by treatment of the crude product with sodium methoxide in methanol provided hydantoin 3 in 91% yield after column chromatography.…”

Spectroscopic Evidence for Through-Space Arene–Sulfur–Arene Bonding Interaction in m-Terphenyl Thioether Radical Cations

“…In this context electron-rich groups commonly encountered in proteins dramatically affect the oxidation potential of thioethers. In model systems, neighboring S or O atoms, amides, , and arenes have all been found to significantly lower the oxidation potential of thioethers. This is mainly due to the formation, in the radical cations, of two-center–three electron (2c, 3e) bonds , between the sulfur and neighboring atoms carrying lone pairs, or [S ∴ π] + bonds with neighboring aromatic moieties .…”

Estudos Exploratórios da oxidação eletroquímica de sulfetos vinílicos Δ(5,6)- e Δ(6,7)-insaturados

“…Estes resultados podem ser explicados em termos da participação do grupo vizinho, carboxilato ou hidroxila, na oxidação de tioéteres mediada por íons brometo. R R=HouMe O comportamento do composto 9 11 é diferente pois nenhum efeito catalítico foi registrado na presença de íons brometo. Eletrólises a potencial controlado em MeCN contendo água e excesso de 2,6-di-t-butilpiridina, levaram à formação de uma mistura de sulfóxidos diastereoméricos em 60 e 25-30% de rendimento, respectivamente.…”

“…Torii et al 12 ao realizarem a oxidação anódica do difenil sulfeto (1), em acetonitrila contendo LiCI04, observaram a formação de perclorato de difenil p-(feniltio)fenil sulfônio (11), difenil sulfóxido (2), e 1,4-bisfeniltiobenzeno (12). O sal de sulfônio (11), predomina na ausência de água, enquanto que a proporção de 2 aumenta com o aumento da concentração de água (Esquema 1.1, e Tabela 1.1).…”