A Pair of New Spirocyclic Alkaloid Enantiomers with TrxR Inhibitory Activities Were Isolated from Marine-Derived Aspergillus ruber TX-M4-1

One new spirocyclic alkaloid,5-isopentenyl-cryptoechinuline D(1),along with 11 known compounds(2–12),were iso-lated from a marine fungus Aspergillus ruber TX-M4-1.The structures of compounds 1–12 were elucidated by spectroscopic evi-dences.Compound 1 was initially isolated as an enantiomer,and further separation of 1 by chiral HPLC afforded a pair of enantio-mers,including(-)-5-isopentenyl-cryptoechinuline D(1a)and(+)-5-isopentenyl-cryptoechinuline D(1b).Their absolute configura-tions were elucidated by ECD spectroscopic data.Compounds 1a,5 and 10 could inhibit thioredoxin reductase(TrxR)activity with IC50 values of 6.2,36.3 and 18.6μmol L^(-1),respectively.Surface plasmon resonance(SPR)study also demonsrated the interactions between compounds 6,8 and Niemann-Pick C1 Like 1(NPC1L1)respectively,which indicate that compounds 6 and 8 are potential NPC1L1 inhibitors.

Synthesis, Structure and Antimicrobial Activity of 2-Phenyl-4H-spiro[benzo[e][1,4,2]oxaza- phosphinine-3,3′-indolin]-2′-one 2-oxide

A novel spiro-compound（C20 H15 N2 O3 P） has been synthesized and characterized by means of IR and 1H NMR. Its crystal structure was determined by X-ray diffractometry. The crystal belongs to the monoclinic system, space group P21 /c with a = 9.1628（7）, b = 12.9490（7）, c = 15.7898（11）, β = 103.952（8）o, Mr = 36.08, V = 1818.2（2）3, Z = 4, Dc = 1.382 g/cm3, F（000） = 788, μ = 0.179 mm-1, R = 0.0701 and wR = 0.1513. The preliminary biological test showed that the title compound has activities against Escherichia coli, S.albus, Bacillus subtilis, Staphylocc- ocusaureus and Micrococcus tetragenus with MIC to be 0.038, 0.038, 0.075, 2.48, and 0.15 mg/mL, respectively.

Syntheses and Crystal Structures of Two Tin(Ⅳ) Complexes with Aminosilane Bearing Ligand

Aminosilane bearing bulky substituents on nitrogen： LH2 （L = Me2Si（NDipp＇）2, Dipp = 2,6-diisopropylphenyl） was reacted with BuLi in toluene. The resulting bulky chelating dianion Me2Si（NDipp）2 was used to synthesize the unusual spirocyclic heterotriatomic complex [MeESi（NDipp）2]ESn （1） by its reaction with SnCl4 and the bulky heterotriatomic complex Me2Si（NDipp）2SnPh2 （2） with Ph2SnC12. 1 belongs to the monoclinic system, space group P21/n with a = 13.193（2）, b = 20.663（3）, c = 20.403（3）A, β = 99.954（2）°, V = 5478.3（15） A3, C55H85.5N4Si2Sn, Mr = 977.64, Z = 4, Dc. = 1.185 Mg/m3, μ（MoKa） = 0.547 mm-1, F（000） = 2086, S = 1.000, the final R = 0.0614 and wR = 0.1322 for 14446 observed reflections （1 〉 2σ（I）） and R = 0.0797 and wR = 0.1456 for all data. 2 belongs to the triclinic system, space group P1 with a = 10.36（15）, b = 13.204（7）, c = 14.363（7） A, a = 90.214（10）, β = 106.182（7）, y = 109.854（8）°, V = 1764.4（15） A3, C38HsoN2SiSn, M,. = 681.58, Z = 2, Dc = 1.283 Mg/m^3,μ（MoKa） = 0.785 mm-1, F（000） = 712, S = 1.002, the final R = 0.0498 and wR = 0.0955 for 7533 observed reβections （I 〉 2σ（I）） and R = 0.0676 and wR = 0.1018 for all data. In the structure of 1, the tin atom is located in the spirocyclic center of the two fused four-membered SnN2Si rings. The two complexes were characterized by ^1H NMR, elemental analysis, and single-crystal X-ray structural analysis.

A Facile Synthesis of N-Substituted Spirocyclic Diester of α-Aminophosphonic Acid

A simple and direct method for preparation of N-substituted spirocyclic dieSter of □-amino phosphonic acid (4) in high yield is introduced. The reaction consists of the threecomponent reachon of phenylurea (1), an aromatic aldehyde (2), and 3,9-dichloro-2,4,8,10-tetraoxa- 3, 9 -diphosphaspiro [5,5] undecane (3) in anhydrous benzene.

Electrochemical Dearomative Spirocyclization of N-Acyl Sulfonamides in a Continuous-Flow Cell

The development of efficient and sustainable methods to obtain spirocyclic compounds is of significance as these structures are widely found in pharmaceuticals and agrochemicals.Herein,we disclose an electrochemical dearomative spirocyclization of N-acyl sulfonamides in a continuous-flow cell.The reaction is simple and efficient without external catalysts or supporting electrolytes and could be applied in a decagram-scale synthesis.

“Steric Armor”Strategy of Blue Fluorescent Emitters against Photooxidation-Induced Degradation

Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Generally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9′-fluorene](SFDBA)to pack tightly to resist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a“steric armor”,protecting the photosensitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the photoluminescence quantum yields(PLQYs)of the crystalline film is 327%higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.

Cobalt-Catalyzed Switchable[4+1]and[4+1+1]Spirocyclization of Aromatic Amides with 2-Diazo-1H-indene-1,3(2H)-dione:Access to Spiro Indene-2,1'-isoindolinones and Spiro Isochroman-3,1'-isoindolinones

Herein,we report a condition-controlled divergent synthesis of spiro indene-2,1'-isoindolinones and spiro isochroman-3,1'-isoindolinones through cobalt-catalyzed formal[4+1]and[4+1+1]spirocyclization of aromatic amides with 2-diazo-1H-indene-1,3(2H)-dione.When the reaction is carried out under air in ethyl acetate,spiro indene-2,1'-isoindolinones are formed through Co(II)-catalyzed C—H/N—H[4+1]spirocyclization.When the reaction is run under O2 in CH3CN,on the other hand,spiro isochroman-3,1'-isoindolinones are generated through Baeyer-Villiger oxidation of the in situ formed spiro indene-2,1'-isoindolinones with O2 as a cheaper and environmental-friendly oxygen source.In general,these protocols have advantages such as using non-precious and earth-abundant metal catalyst,no extra additive,high efficiency and regioselectivity.A gram-scale synthesis and the removal of the directing group further highlight its utility.

Aromatic and olefinic C–H alkenylation by catalysis with spirocyclic NHC Ru(Ⅳ) pincer complex

Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.

Rh(III)-catalyzed [5+1] spirocyclization to produce novel benzimidazole-incorporated spirosuccinimides

Transition-metal-catalyzed cross-coupling reactions as very efficient and atom-economical approaches have been widely used to build up complex heterocyclic compounds.However,modification of 2-oxyl benzimidazole skeleton using maleimide compounds via C–H activation has remained unprecedented.Herein,we developed a rhodium(III)-catalyzed[5+1]cascade spiroannulation to construct diversified novel benzimidazole-incorporated spirosuccinimide derivatives from 2-oxyl benzimidazoles and maleimides.

Chemical Constituents from Hypericum beanii

Objective To study the chemical constituents from the aerial parts of Hypericum beani/. Methods Various chromatographic techniques were used to separate the constituents and their structures were elucidated on the basis of extensive spectroscopic interpretation. Results Fifteen compounds were isolated from the aerial parts of H. beanii. Their structures were identified as hyperbeanol E （1）, （E）-Iinalool-l-oic acid （2）, （4S,5R）-5-（4＇-methyl-3＇-pentenyl）-4-hydroxy-5-methyl- dihydrofuran-2-one （3）, benzoic acid （4）, 4-（3-O-3＂）-3＂-methylbutenyl-6-phenyl- pyran-2-one （5）, 4-hydroxy-4a,7-dimethoxy-4,4a-dihydrodibenzo-p-dioxJn-2（3H）- one （6）, isoimperatorin （7）, 2,3-dimethoxyxanthone （8）, 3,4-dihydroxy-2- methoxyxanthone （9）, osajaxanthone （10）, nigrolineaxanthone F （1 1）, hypercohone G （12）, betulinic acid （1 3）, oleanolic acid 3.13-caffeate （14）, and isoastilbin （1 5）. Conclusion Compound 1 is a new menthane monoterpene derivative which owns an extra lactone ring. Compounds 2-7 and 10-1 5 are isolated from genus Hypericum Linn. for the first time and the other compounds are first obtained from the plants in H. beanii.

A spirocyclic oxindole analogue:Synthesis and antitumor activities

A new synthesis of spirocyclic oxindole analogue spiro[piperidine-4,3＇-pyrrolol2,3-b]pyridin]-2＇（1＇H）-one 1 is described. The key steps involve dialkylation of arylacetonitrile and cyclization of the azaoxindole ring by an intramolecular Buchwald-Hartwig amidation of carboxylic amide and aryl chloride. A small library was obtained by reductive amination of 1 with various aldehydes and was screened against human lung cancer cell A549, human liver cancer cell BEL7402, and human colon cancer cell HCT-8. The results show that most of the library compounds 2 have some inhibitory activities. 2-（Trifluoromethoxy） benzylic substituted spirocyclic azaoxindole 2e was identified as a nanomolar inhibitor against human lung cancer cell A-549 （IC50 = 50 nmol/L）.

Carbazole-endcapped Spiro[fluorene-9,9＇-xanthene] with Large Steric Hindrance as Hole-transporting Host for Heavily-doped and High Performance OLEDs

In this work, we designed and synthesized a novel spirocyclic compound functionalized spiro[fluorene-9,9＇- xanthene] with carbazole group （2-carbazolyl-spiro[fluorene-9,9＇-xanthene], SFX-Cz） via Friedel-Crafts and Ullmann reaction, which is expected to own high thermal and morphological stability, and good carrier injection/ transporting properties due to the excellent hole transporting characteristics of carbazole and cruciform structure of spiro[fluorene-9,9＇-xanthene]. The carbazole end-capped spiro[fluorene-9,9＇-xanthene] SFX-Cz based PhOLEDs with Flrpic as phosphor emitter have been researched by varying dopant concentration, which exhibit the maximum EQEs of 8.9%, 7.4%, 9.1%, and 4.7% with the doping increasing from 10% to 50%. The higher performance PhOLEDs are independent on concentration variation from 10% to 30%, which suggests the bulky steric hindrance of SFX-Cz might be a potential canditate for high performance and inexpensive device with simplified process.

Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety

In order to develop novel spirocyclic tetronic acid lead compounds,a series of new spirocyclic tetronic acid derivatives containing oxime ether moiety was synthesized and bioassayed.The stmctures of 16 target compounds were characterized by lH NMR spectra,13C NMR spectra and high-resolution mass spectrometer(HRMS).Preliminary bioassays indicated that most of the title compounds displayed excellent insecticidal activity against Aphis fabae and Nilapmyata lugens at 100 mg/L.In particular,compound 6k showed the similar activity(LC50=6.87 mg/L)against A.fabae as the spirotetramat(LC50=4.56 mg/L)and had better efIects(LC50=l.64 mg/L)against N.lugens in comparison with spirotetramat(LC5o=7.90 mg/L).The study showed that compound 6k exhibited more promising and broad-spectrum insecticide activity and may serve as a new insecticidal agent for sucking pests.

Asymmetric Double Michael Reaction Catalyzed by Simple Primary Amine Catalysts： A Straightforward Approach to Construct Spirocyclic Oxindoles

The enantioselective double Michael reaction of N-Boc-3-nonsubstitued oxindoles with dienones catalyzed by chiral monoimide protected cyclohexane-1,2-diamines was developed. A wide range of optically active spirocyclic oxindoles were obtained up to 98% yield and up to 89% ee.

Harnessing the cyclization strategy for new drug discovery

The design of new ligands with high affinity and specificity against the targets of interest has been a central focus in drug discovery.As one of the most commonly used methods in drug discovery,the cyclization represents a feasible strategy to identify new lead compounds by increasing structural novelty,scaffold diversity and complexity.Such strategy could also be potentially used for the follow-on drug discovery without patent infringement.In recent years,the cyclization strategy has witnessed great success in the discovery of new lead compounds against different targets for treating various diseases.Herein,we first briefly summarize the use of the cyclization strategy in the discovery of new small-molecule lead compounds,including the proteolysis targeting chimeras(PROTAC)molecules.Particularly,we focus on four main strategies including fused ring cyclization,chain cyclization,spirocyclization and macrocyclization and highlight the use of the cyclization strategy in lead generation.Finally,the challenges including the synthetic intractability,relatively poor pharmacokinetics(PK)profiles and the absence of the structural information for rational structure-based cyclization are also briefly discussed.We hope this review,not exhaustive,could provide a timely overview on the cyclization strategy for the discovery of new lead compounds.

Development of unique dianionic Ir(Ⅲ) CCC pincer complexes with a favourable spirocyclic NHC framework

A new type of dianionic Ir(Ⅲ) CCC pincer complexes(SNHC-Ir, 1a–1c) is successfully designed and synthesized by developing a one-step methodology, which involves an initial coordination of Ir(I) with the NHC and subsequent metallation of double sp2C–H bonds. This method is considerably useful over those reported by using strong coordination ligand or carbonic anion exchange,and would provide an alternative efficient template of organometallics synthesis. Experimental and density functional theory(DFT) calculation results indicate that the spirocyclic framework is a favourable factor for the facile formation and stabilization of these complexes. Primary investigation shows that chloride 1b can well catalyze homo and hetero addition of styrene derivatives and remote olefin isomerization, which represents the first catalytic application of the dianionic CCC pincer complexes.

Rapid assembly of 1,3-indanedione-based spirocyclic tetrahydroquinolines for inducing human lung cancer cell apoptosis

The rapid collection of a library of biologically relevant molecules is essential in new drug discovery.Here we show a variety of bioactive 1,3-indanedione-based spirocyclic tetrahydroquinolines that have been concisely and efficiently constructed under the guidance of biology-oriented synthesis(BIOS).Using Pd(PPh_(3))_(4) as a catalyst,various 2-arylidene-1,3-indanediones can react with vinyl benzoxazinanones under the mild condition to afford a new class of spirocyclic tetrahydroquinolines in moderate to excellent yields(45%-99%)with high stereocontrol(>95:5 diastereoselectivity).Their structures were unambiguously confirmed by X-ray single crystal analysis.The biological evaluation revealed that two of the 1,3-indanedione-based spirocyclic tetrahydroquinolines show remarkable apoptosis-inducing activities over A549 human lung cancer cells,exceeding that of cisplatin.The antitur activities were triggered by reactive oxygen species,commonly overproduced in cancer cells.The clinical demand for antitumor chemotherapy for lung cancer has encouraged an all-out search for analogues with lower toxcity,improved therapeutic index and increased activity.

N-Heterocyclic Carbene-Catalyzed All Carbon-[4+2] Cyclocondensation of α,β-Unsaturated Acyl Chlorides with 3-Alkylenyloxindoles

Although the NHC-catalyzed cyclization reactions have been well established for the synthesis of various heterocycles,the corresponding all carbon cyclization reaction for the synthesis of carbocycles is far less established.In this note,the NHC-catalyzed all carbon[4+2]cyclocondensation of α,β-unsaturated acyl chlorides and 3-alkenyloxindoles was developed to give the corresponding spirocarbocyclic oxindoles in good yield with good to high diastereoselectivities.

Double[3+2] cycloaddition of nitrile oxides with allenoates:Synthesis of spirobidihydroisoxazoles

The double [3 + 2] cycloaddition of allenoates with nitrile oxides is presented. The reaction worked well under mild reaction conditions to give the spirobidihydroisoxazole in moderate to excellent yields with excellent diastereoselectivities. The two dihydroisoxazole rings have been formed via a sequential double [3 + 2] cycloaddition.

Dearomative spirocyclization via visible-light-induced reductive hydroarylation of non-activated arenes

A visible-light-induced spirocyclizative hydroarylation via reductive dearomatization of a series of non activated arenes including 2-phenyl indoles and naphthalene derivatives under mild conditions is de scribed.An intriguing chemoselective dearomative hydroarylation of 2-phenyl indoles is presented.Th dearomative hydroarylation protocol rapidly delivers valuable spirocycles with carbon-carbon doub bonds from readily accessible aromatic precursors in a single step.