ABSTRACT
A vinylogous addition reaction of allyl aryl ketones with good yields and excellent regioselectivity catalyzed by squaramide catalysts has been developed. A series of chiral tertiary alcohols and bicyclic pyrrolidones could be synthesized in good to excellent yields, enantioselectivities, and diaseteroselectivities. Both experimental results and DFT calculations indicate that 1,2-addition reaction is favorable when the reaction is employed at a lower temperature, while the 1,4-addition/cyclization pathway is favorable when the reaction is employed at a higher temperature. Furthermore, the formation of compound 4 can potentially arise from either the 1,4-addition/cyclization pathway or retro-aldol reaction of compound 3, followed by subsequent 1,4-addition/cyclization.
ABSTRACT
In this study, we developed an organocatalyst-controlled site-selectivity switchable Friedel-Crafts reaction of 1-naphthols and 2,3-dioxopyrrolidines. The o-selective Friedel-Crafts reaction was achieved with chiral tertiary amines, while the p-selective Friedel-Crafts reaction was accomplished with Brønsted acids or Lewis acids. With this protocol, a range of functionalized polycyclic 2-pyrrolidinone derivatives were prepared. Moreover, theoretical mechanistic investigations provided insights into the site-selectivity reaction pathway and the origin of chiral induction for the o-selective Friedel-Crafts reaction.
ABSTRACT
Two reagent-controlled regiodivergent annulation protocols for Achmatowicz products with vinylogous nucleophiles have been developed, which furnished a series of bicyclic cyclopenta[b]pyrans and 8-oxabicyclo[3.2.1]octane derivatives in 28-90% yields. Plausible mechanisms were proposed to involve either Pd-catalyzed Tsuji-Trost allyl-allyl coupling and concomitant Michael cyclization or quinine-promoted cascade stepwise [5 + 2] cycloaddition and intramolecular Michael cyclization.
Subject(s)
Octanes , Pyrans , Stereoisomerism , Indicators and ReagentsABSTRACT
In this work, the development and application of multicomponents obtained from recycled polyethylene terephthalate (r-PET) waste and monotropic liquid crystals as anticorrosion coatings are reported. The r-PET raw material was alcoholyzed and reproduced as a thermoplastic polyester elastomer (TPEE) with different amounts (n%, n = 0, 1, 3, and 5) of 1,6-hexanediamine (HDA). Then, a fluorine-containing liquid crystal (4-cyano-3-fluorophenyl 4-ethylbenzoate (4CFE)) was incorporated into the TPEE mixture via solvent blending to modify and enhance the water resistance. The adhesion behavior of the coating on glass and iron substrates was evaluated by cross-cut tests and immersion tests in aqueous NaCl. In the corrosion resistance measurements, all of the coating samples fabricated with 10 ± 1 mm thickness were less active toward electrochemical corrosion (PEF% > 99%) than the bare iron plate, indicating that our work provided better protection against corrosion of the iron plate.
ABSTRACT
The δ subunit-containing GABAA receptor [GABAA(δ)R], which is exclusively situated in the extrasynaptic space, has considerable influence on emotion and behavior. Although the expression of this receptor experiences dramatic fluctuation during postnatal development, it remains unknown whether it regulates emotion in a development-dependent manner. Here, by using mice with genetic deletion of GABAA(δ)R (knockout) and their wild-type littermates, we examined the role of GABAA(δ)R in regulating anxiety-like behavior, as measured with open field test (OFT) and elevated plus maze during the transition from puberty to adulthood. We observed that for female mice, the knockout ones at puberty but not adulthood showed increased anxiety-like behavior in the OFT relative to their wild-type littermates. However, such increase was not observed in elevated plus maze. For male mice, no between-genotype differences were observed in both tests at the above two developmental stages. Our results suggest that GABAA(δ)R preferentially affects the anxiety-like behavior in OFT in a development-dependent manner, but only in female mice.
Subject(s)
Anxiety/physiopathology , Receptors, GABA-A/physiology , Sex Characteristics , Age Factors , Animals , Female , Male , Mice, Inbred C57BL , Mice, Knockout , Receptors, GABA-A/geneticsABSTRACT
Emerging evidence indicates that loss of inhibitory tone in amygdala with its subsequent overactivation contributes to the development of multiple mental disorders such as anxiety disorders and post-traumatic stress disorder (PTSD). Harmine is a member of natural ß-carboline alkaloids which can readily cross the blood brain barrier and displays significant antidepressant and anxiolytic effects in rodents. However, the underlying neurobiological mechanisms are largely unknown. Here, by using whole-cell patch clamp recordings in in vitro amygdala slices, we examined the effect of harmine on glutamatergic and GABAergic transmission onto basal amygdala (BA) projection neurons (PNs). Our results showed that harmine affected neither the amplitude nor the frequency of spontaneous and miniature excitatory postsynaptic currents (sEPSCs/mEPSCs) of PNs. By contrast, it markedly increased both the amplitude and frequency of the spontaneous inhibitory postsynaptic currents (sIPSCs). For mIPSCs, only an increase of their frequency but not amplitude was observed following harmine perfusion, suggesting that harmine might act through presynaptic mechanism. In parallel, a reduction of paired-pulse ratio of evoked IPSCs emerged in the presence of harmine. Furthermore, the intrinsic excitability of PNs was dramatically decreased upon harmine treatment. Together, our study suggests that harmine selectively potentiates the inhibitory but not excitatory transmission onto BA PNs, which may contribute to its antidepressant and anxiolytic influence.
