155438-98-5Relevant academic research and scientific papers
Lewis Base Catalyzed, Sulfenium Ion Initiated Enantioselective, Spiroketalization Cascade
Denmark, Scott E.,Hilby, Kimberly M.
, p. 14250 - 14289 (2021/11/12)
A Lewis base catalyzed, enantioselective sulfenocyclization of alkenes to afford [6,6]spiroketals has been developed. The method uses a chiral Lewis base catalyst with an electrophilic sulfur source to generate enantioenriched thiiranium ion with alkenes. Upon formation, the thiiranium ion is subsequently captured in a cascade-type reaction, wherein a ketone oxygen serves as the nucleophile to open the thiiranium ion and an alcohol provides the secondary cyclization to form biorelevant spiroketals. A variety of electron-rich and electron-neutral E-substituted styrenes form the desired spiroketals in good yields with excellent enantio- and diastereoselectivities. Alkyl-substituted and terminal alkenes participate in the cascade reaction, but with a limited scope compared to the styrenyl substrates. This method allows for rapid formation of highly substituted spiroketals in good yield and excellent enantioselectivity.
Synthesis of the 1,3,4-Oxadiazole Core through Thermolysis of Geminal Diazides
Erhardt, Hellmuth,Mohr, Fabian,Kirsch, Stefan F.
supporting information, p. 5629 - 5632 (2016/12/14)
The thermolysis of geminal diazides derived from acylacetate compounds is an efficient tool for the rapid construction of the 1,3,4-oxadiazole core. While a broad range of ethyl esters undergoes smooth transformation to the desired heterocycles that contain the ester moiety in moderate to high yields, the analogous tert-butyl esters give rise to the oxadiazoles with acyl groups, presumably through a pathway of decarboxylation followed by a new acyl transfer.
Bis(trimethylsilyl) Sulfate Catalysis in γ-Lactonization of Cyclopropanecarboxylates Activated by Carbonyl Substituents on α-Carbon
Morizawa, Yoshitomi,Hiyama, Tamejiro,Oshima, Koichiro,Nozaki, Hitosi
, p. 1123 - 1127 (2007/10/02)
The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)-C(2) bond cleavage to produce γ-lactones.Stereochemically, the reaction takes two pathways: (1) substrates with a cationstabilizing group like vinyl on C(2) give thermodynamically favored γ-lactones having the thermodynamically more stable arrangement of substituents irrespective of the configuration of the cyclopropane substrates, (2) substrates without such a cation-stabilizing group afford γ-lactones under ca. 70percent inversion at C(2) reaction center.
