Comprehensive Summary Cyclobutane derivatives have been recognized as useful structural motifs in organic synthesis and drug design. With the revival of photochemistry, the enantioselective synthesis of cyclobutane derivatives using [2 + 2]‐cycloadditions has garnered numerous attentions. On the other hand, enantioselective functionalization of preformed four‐membered carbocycles is emerging as an important complementary approach to access chiral cyclobutane derivatives with versatile structural patterns. Herein, we summarize recent advances in this field from 2012. To avoid undesired C—C bond cleavage driven by strain‐releasing, it is crucial to choose compatible methods for enantioselective functionalization and meanwhile preserving intact four‐membered ring skeleton. Guided by calculated hydrogenation enthalpies, which are used to evaluate the strain energy of indicated C—C bond, a clear picture of the developed methodologies on functionalization of four‐membered carbocycles combining the strain energy and enhanced reactivity is presented.

Here, fluorescent carbon nanodots (CNDs) were generated using water extract of tomato leaves. Sphere nanodots were formed within 30 min by a one-step microwave heating. An ultraviolet 360 nm photoluminescence (PL) peak was found upon high-energy excitation. This peak showed excitation-independent property, and might belong to some solely-emitting fluorescent moieties attaching to the CNDs. The biomolecules with complex chemical structure in the plant leaves were responsible for the unique spectral property of the CNDs. Taking advantage of their special property, the CNDs were applied as an fluorescent probe for spectral-matching sensing of chromium(VI) [Cr(VI)] in the aqueous solution. The detection limit was as low as 79 nM, and the CNDs probe showed good selectivity towards other metal ions. Real sample tests using the tap water were also carried out, showing potential of the CNDs in the practical applications.

The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529) has aroused concerns over their increased infectivity and transmissibility, as well as decreased sensitivity to SARS-CoV-2-neutralizing antibodies (NAbs) and the current coronavirus disease 2019 (COVID-19) vaccines. Such exigencies call for the development of pan-sarbecovirus vaccines or inhibitors to combat the circulating SARS-CoV-2 NAb-escape variants and other sarbecoviruses. In this study, we isolated a broadly NAb against sarbecoviruses named GW01 from a donor who recovered from COVID-19. Cryo-EM structure and competition assay revealed that GW01 targets a highly conserved epitope in a wide spectrum of different sarbecoviruses. However, we found that GW01, the well-known sarbecovirus NAb S309, and the potent SARS-CoV-2 NAbs CC12.1 and REGN10989 only neutralize about 90% of the 56 tested currently circulating variants of SARS-CoV-2 including Omicron. Therefore, to improve efficacy, we engineered an IgG-like bispecific antibody GW01-REGN10989 (G9) consisting of single-chain antibody fragments (scFv) of GW01 and REGN10989. We found that G9 could neutralize 100% of NAb-escape mutants (23 out of 23), including Omicron variant, with a geometric mean (GM) 50% inhibitory concentration of 8.8 ng/mL. G9 showed prophylactic and therapeutic effects against SARS-CoV-2 infection of both the lung and brain in hACE2-transgenic mice. Site-directed mutagenesis analyses revealed that GW01 and REGN10989 bind to the receptor-binding domain in different epitopes and from different directions. Since G9 targets the epitopes for both GW01 and REGN10989, it was effective against variants with resistance to GW01 or REGN10989 alone and other NAb-escape variants. Therefore, this novel bispecific antibody, G9, is a strong candidate for the treatment and prevention of infection by SARS-CoV-2, NAb-escape variants, and other sarbecoviruses that may cause future emerging or re-emerging coronavirus diseases.

We report here a sequential enantioselective reduction/C-H functionalization to install contiguous stereogenic carbon centers of benzocyclobutenols and cyclobutanols. This strategy features a practical enantioselective reduction of a ketone and a diastereospecific iridium-catalyzed C-H silylation. Further transformations have been explored, including controllable regioselective ring-opening reactions. In addition, this strategy has been utilized for the synthesis of three natural products, phyllostoxin (proposed structure), grandisol and fragranol.

Abstract We reported here a facile synthesis of dibenzo[a,e]cyclooctene-5,11(6H,12H)-diones via dimerization of benzocyclobutenones in the presence of simple base via the elusive benzocyclobutenone anion. The temperature effect played a crucial role in the dimerization reaction. Further synthesis of 5,11-disubstituted dibenzo[a,e]cyclooctenes (dibenzo[a,e][8]annulenes) from dibenzo[a,e]cyclooctene-5,11(6H,12H)-diones was also explored.

A practical synthesis of enantioenriched indane derivatives with quaternary stereocenters was developed via sequential enantioselective reduction and C-H functionalization. Good to excellent enantioselectivity could be achieved by either the CuH-catalyzed asymmetric reduction or the Corey-Bakshi-Shibata (CBS) reduction of indanone derivatives. The subsequent diastereospecific and regioselective rhodium-catalyzed silylation of the methyl C-H bond led to indane derivatives with quaternary centers. This strategy was further applied in syntheses of (nor)illudalane and botryane sesquiterpenoids.

Summary of main observation and conclusion Divergent skeleton rearrangements of cyclobutanones under simply basic conditions have been described. The reaction pathway is controlled by the nature of Z group on 3‐substituted cyclobutanones, leading to the formation of various lactones, lactams and acids. Preliminary results on enantioselective reaction were also reported.

Self-assembly of the amphiphilic copolymer into core-shell-like nanoparticles is the new tactic to tailor carriers toward rationalization in the field of drug-delivery systems. Herein, a facile route for examining how the entrapment of a hydrophobic and negative-charge drug affects the micellar structure of a positive-charged copolymer and its biological behavior was developed. In this study, Pluronic F127-grafted chitosan (CF127) was utilized as a positive-charged copolymer for in situ loading of nanocurcumin in a cosolvent condition. Ultrasonication was found to be an effective method to control the self-assembly of phosphocasein and its interaction with curcumin. The superstructure of the incorporated nanoparticles was fabricated in the medium under unimolecular micelles as vesicular structure (SV) at lower ultrasonic condition while large complex micelles (multimicelle aggregates, LCMs) at higher ultrasonic power density. According to transmission electron microscopy, variable UV-visible spectrophotometry, as well as fluorescence spectroscopy, nanocurcumin was not only incorporated into the hydrophobic micelle cores via hydrophobic interaction but also underwent electrostatic interaction with amine groups on chitosan backbone, resulting in micellar aggregation and finally turning in LCMs. Furthermore, regarding dynamic light scattering measurements, correlation coefficients of SV, as well as LCMs, were higher than 0.9, which means that all nanostructures were homogeneous in size under precise control by ultrasonication. Cell-culture studies showed that both unique morphologies endowed fibroblast cell development. Interestingly, the more complex structure as LCM exhibited as a potential candidate in cancer therapy. These corollaries suggest that the morphology of micelles based on cationic amphiphilic block copolymer can be modulated by adding negative-charged/hydrophobic molecules under varying condition of ultrasonication that reinforces their prospective applications as nanocarriers for drug-delivery systems.

The enantioselective intramolecular α-arylation of cyclobutanones has been established by combining palladium and enamine catalyst systems. Two different enantioselective control strategies have been developed for cyclobutanone substrates bearing O- or N-tethered aryl bromides. Further synthetic applications are also reported.

At room temperature, dibenzoyl peroxide undergoes oxidative addition reaction with metallic copper powder and pyridine N-oxide (triphenylphosphine oxide or 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthrolin) which affords the last products as binuclear copper(II) complexes, [Cu(C5H5NO)-(C6H5COO)2]2(1), [Cu(OPPh3)(C6H5COO)2]2(2) and [Cu(C6H5COO)(C26H20N2)](3, C26H20N2 is 2,9-dimethyl-4,7-diphenyl-l,l∼phenanthrolin). The structure of the Complexes were characterized by elemental analyses. IR spectra, TGDTA and magnetic property. Crystals(1) are triclinic, space group P1, a=0.92617(36), b=1.06973(17), c=1.08813(29) nm, a=59.60(2)°, β=74.83(3)°, γ=72.80(2)°, V=0.880 nm3, Dc = 1.520 g/cm3. Z=1, R=0.044, R,=0.048, Mr=805.78, 3477 reflections with I > 3o(I). Esch copper(II) ion is coordinated by two bridging bidentate benzoate ligands and one pyridine N-oxide or triphenylphosphine oxide to form dimeric binuclear molecules. The structure of the compound(1) shows a clear centre of symmetry.

Four copper( II) complexes were synthesized at room temperature by oxidative addition reaction of metallic copper powder and dibenzoyl peroxide in the presence of ligands(2,2'-bipy,dppe, 2 -aminopyridine and benzoimidazole, respectively). Four copper( I) complexes were synthesized by reduction substitution reaction of copper( II)salts with different diphosphine ligands[Ph2P(CH2)(n)PPh2, dppm(n =1),dppe(n =2),dppp(n =3)and dppb(n =4)]. The complexes were characterized by elemental analysis and single crystal X-ray analysis. The reaction mechanism was discussed on the basis of electronic spectra. A facile synthetic method of copper(I,II) complexes was provided.