Hydrogen bonding-induced aromatic oligoamide foldamers as spherand analogues to accelerate the hydrolysis of nitro-substituted anisole in aqueous media.
Four intramolecular hydrogen bonding-driven aromatic amide foldamers 2-5 have been designed and synthesized in which a 2-methoxy-3-nitrobenzamide unit was incorporated at the end of the backbone. Kinetic studies in dioxane-water (4:1, v/v) at 60-90 degrees C have revealed that the folded backbone of the oligomers was, like the rigidified spherand, able to complex Li+, Na+, and K+ and, consequently, accelerated the hydrolysis of the nitro-appended anisole unit of the foldamers. Generally, longer foldamers displayed an increased accelerating effect, and LiOH displayed the highest reactivity probably due to the most efficient complexation by the folded oligomers. Addition of excessive potassium chloride substantially reduced the complexing interaction, and the hydrolysis of the longer oligomers became slower than that of the shorter ones due to an increased steric effect. The results indicate that, even in a hot aqueous medium of high polarity, intramolecular hydrogen bonding is still able to induce structurally matched oligomers to generate a preorganized rigidified conformation.
Yi
Hui-Ping
HP
State Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
Wu
Jiang
J
Ding
Kui-Ling
KL
Jiang
Xi-Kui
XK
Li
Zhan-Ting
ZT
D000577:Amides / Q000737:chemistry*; D000840:Anisoles; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D006860:Hydrogen Bonding; D006868:Hydrolysis; D007700:Kinetics; D018020:Lithium Compounds / Q000737:chemistry; D008968:Molecular Conformation; D009574:Nitro Compounds / Q000737:chemistry*; D009578:Nitrobenzenes / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011189:Potassium Chloride / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry*
D000577:Amides; D000840:Anisoles; D006841:Hydrocarbons, Aromatic; D018020:Lithium Compounds; D009574:Nitro Compounds; D009578:Nitrobenzenes; D011108:Polymers; D014867:Water; D011189:Potassium Chloride; C060998:anisole; C036077:nitrobenzene; C028467:lithium hydroxide