Stereodivergent, Diels-Alder-initiated organocascades employing α,β-unsaturated acylammonium salts: scope, mechanism, and application was written by Abbasov, Mikail E.;Hudson, Brandi M.;Tantillo, Dean J.;Romo, Daniel. And the article was included in Chemical Science in 2017.Quality Control of (S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole hydrochloride This article mentions the following:
Chiral α,β-unsaturated acylammonium salts are novel dienophiles enabling enantioselective Diels-Alder-lactonization (DAL) organocascades leading to cis- and trans-fused, bicyclic γ- and δ-lactones from readily prepared dienes, commodity acid chlorides, and a chiral isothiourea organocatalyst under mild conditions. The authors describe extensions of stereodivergent DAL organocascades to other racemic dienes bearing pendant secondary and tertiary alcs., and application to a formal synthesis of (+)-dihydrocompactin is described. A combined exptl. and computational study of unsaturated acylammonium salt formation and the entire DAL organocascade pathway provide a rationalization of the effect of Bronsted base additives and enabled a controllable, diastereodivergent DAL process leading to a full complement of possible stereoisomeric products. Evaluation of free energy and enthalpy barriers in conjunction with exptl. observed temperature effects revealed that the DAL is a rare case of an entropy-controlled diastereoselective process. NMR anal. of diene alc.-Bronsted base interactions and computational studies provide a plausible explanation of observed stabilization of exo transition-state structures through H-bonding effects. In the experiment, the researchers used many compounds, for example, (S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole hydrochloride (cas: 16595-80-5Quality Control of (S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole hydrochloride).
(S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole hydrochloride (cas: 16595-80-5) belongs to thiazole derivatives. Thiazoles are a class of five-membered rings containing nitrogen and sulfur with excellent antitumor, antiviral and antibiotic activities. The pyridine-type nitrogen in the thiazole ring deactivates the ring for electrophilic substitution reactions, which is further reduced in acid due to protonation of the thiazole ring.Quality Control of (S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole hydrochloride
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica