Properties and Reactions of Thiazole

Thiazoles in Peptides and Peptidomimetics

“…[39] Calculations of the electron density distribution in thiazole by many different methods indicate the sulfur and nitrogen atoms have respectively net positive and negative charges, and C-2 and C-5 are respectively slightly positive, but close to neutral, and slightly negative. [40] The computational results are consistent with experiments indicating nucleophiles attack preferentially at C2, and electrophiles react with C5 ( Fig. 4).…”

“…[43][44][45] Unless activated by electron donating groups (e.g., amino or hydroxyl groups), [46] similar to pi-deficient pyridines, thiazoles typically resist electrophilic attack, due to in part to deactivation by the nitrogen. [40] For example, thiazoles are resistant to nitration, sulfonation and halogenation in strongly acidic media, because nitrogen protonation depletes ring electron density. The C-2 proton possesses greater kinetic and thermodynamic acidity, [40] relative to those at C-4 and C-5, and may be deprotonated with alkyl lithium bases [47] and lithium diisopropylamide [48].…”

“…[40] For example, thiazoles are resistant to nitration, sulfonation and halogenation in strongly acidic media, because nitrogen protonation depletes ring electron density. The C-2 proton possesses greater kinetic and thermodynamic acidity, [40] relative to those at C-4 and C-5, and may be deprotonated with alkyl lithium bases [47] and lithium diisopropylamide [48]. Together with thiazole Grignard reagents, [47] C-lithiated species have been reacted with various carbon electrophiles.…”

Near-Infrared Luminescence and Inner Filter Effects of Lanthanide Coordination Polymers with 1,2-Di(4-pyridyl)ethylene

“…The thermal behavior was determined by simultaneous DTA/TG analyses exemplarily for the coordination polymers ∞ 1 [Nd 2 Cl 6 (dpe) 2 (thz) 4 ]·dpe ( 2 ), ∞ 1 [GdCl 3 (dpe)(py) 2 ]·(dpe/py) ( 3 ), ∞ 1 [DyCl 3 (dpe)(thz) 2 ]·(dpe/thz) ( 8 ) and ∞ 1 [HoCl 3 (dpe)(thz) 2 ]·thz ( 11 ). Knowledge of melting and boiling points of dpe (mp = 150–153 °C and bp = 334 °C), thiazole (mp = −31 °C, bp = 117–118 °C) and pyridine (bp = 114 °C) allows assignment of the differential thermal analysis (DTA)/thermogravimetric (TG) signals of the compounds. All investigated compounds show rather similar thermal behavior with three defined mass losses around 150, 340, and 500 °C, indicating related transformation and decomposition processes.…”