4190-06-1Relevant articles and documents
Rhodium(I)-Catalyzed Enantioselective C(sp3)—H Functionalization via Carbene-Induced Asymmetric Intermolecular C—H Insertion?
Liu, Bo,Xu, Ming-Hua
supporting information, p. 1911 - 1915 (2021/05/31)
Transition-metal-catalyzed C—H insertion of metal-carbene represents an excellent and powerful approach for C—H functionalization. However, despite remarkable advances in metal-carbene chemistry, transition metal catalysts that are capable of enantioselective intermolecular carbene C—H insertion are mainly constrained to dirhodium(II) and iridium(III)-based complexes. Herein, we disclose a new version of asymmetric carbene C—H insertion reaction with rhodium(I) catalyst. A highly enantioselective rhodium(I) complex-catalyzed C(sp3)—H functionalization of 1,4-cyclohexadienes with α-aryl-α-diazoacetates was successfully developed. By using chiral bicyclo[2.2.2]-octadiene as ligand, rhodium(I)-carbene-induced asymmetric intermolecular C—H insertion proceeds smoothly at room temperature, allowing access to a diverse variety of α-aryl-α-cyclohexadienyl acetates and gem-diaryl-containing acetates in good yields with good to excellent enantioselectivities (up to 99% ee). Furthermore, the synthetic utility of the reaction was highlighted by facile synthesis of a novel cannabinoid CB1 receptor ligand. This method may offer a new opportunity for the development of therapeutically exploitable cannabinoid receptor type ligands in medicinal chemistry.
Ozonolysis of 1,4-cyclohexadienes in the presence of methanol and acid. Mechanism and intermediates in the conversion of 1,4-cyclohexadiene derivatives to β-keto esters
Gbara-Haj-Yahia, Isra,Zvilichovsky, Gury,Seri, Noa
, p. 4135 - 4139 (2007/10/03)
Conditions for the preparation of β-keto esters directly from 1,4-cyclohexadiene derivatives are described. This procedure is a further step in the application of the synthetic methodology, which consists of the combination of Birch reduction of available benzene derivatives followed by ozonolysis. In this work, the syntheses of derivatives of dimethyl γ-keto-α-aminoadipate and dimethyl β-keto glutamate from the corresponding 1,4-cyclohexadiene derivatives are described. The latter compounds are prepared from phenylalanine and phenylglycine, respectively. The study of the ozonolysis of simple alkyl derivatives of 1,4-cyclohexadiene in the presence of methanol, both in the presence and absence of acid, helped to establish the mechanism of this reaction. The proximity of the two double bonds, which are cleaved, leads to the intermediate formation of 1,2-dioxolane derivatives that could be identified by NMR spectroscopy. It is shown that regardless of the regioselectivity of the cleavage of the primary ozonide, which is formed, all 1,2-dioxolane derivatives can lead to β-keto esters. This is due to the equilibrium between these dioxolanes in the presence of methanol and acid.
Desymmetrisation and ring opening of cyclohexa-1,4-dienes. An access to highly functionalised cyclic and acyclic systems
Landais, Yannick,Zekri, Elisabeth
, p. 6547 - 6551 (2007/10/03)
Acyclic and cyclic synthons are readily available in three steps starting from substituted arenes. Birch reduction of the latter followed by desymmetrisation through Sharpless AD reaction then ozonolysis thus afforded five-membered ring lactols and acycli
