Columnar catenar bisoxazoles and bisthiazoles

Three new series of catenar liquid crystals 1a–c derived from heterocyclic bisoxazoles and bisthiazoles exhibiting columnar phases were reported. All compounds 1a–c exhibited hexagonal columnar phases, which were confirmed by powder XRD diffractometer. Compounds 1a have a slightly wider temperature range of columnar phases than that of compounds 1b, which might be attributed to higher dipole polarized in 1a. A N_cell and R_ar value equal to 2.54–2.76 and 19.99–20.45 Å² within a slice of 9.0 Å thick were obtained for three derivatives 1a–c (all ns=12), indicating that a single molecule was packed within columns in Col_h phases. All derivatives showed good stabilities at temperature below T=408 °C on TGA. The PL spectra of all compounds 1a–c showed one intense peak at λ_max=505–510 nm, and these photoluminescent emissions originated from quinoxaline moiety.     

Unsymmetric 1,3,4-oxa(thia)diazoles of quinoxaline–naphthalene conjugates

Two new series of unsymmetric 1,3,4-oxa(thia)diazoles 1a,b containing both quinoxaline and naphthalene moieties were prepared and their mesomorphic properties were investigated. The mesomorphic behavior of compounds 1a,b and 2 was studied by DSC analysis and polarized optical microscopy. All compounds 1a and 2 exhibited hexagonal columnar phases (Col_h), which were also confirmed by powder XRD diffractometer. N_cell and R_ar values equal to 5.23 and 22.73 Å² within a slice of 9.0 Å thick were also obtained for 1a (n=16), indicating that a more disc-like structure constructed by two molecules lying side-by-side was correlated in Col_h phases. In contrast, all compounds 1b were not mesogenic, and the lack of mesomorphic properties in 1b might be due to their unfavorable conformations. The PL spectra of all compounds 1a,b showed one intense peak at λ_max=509–512 nm, and these photoluminescent emissions originated from quinoxaline moiety.     

Synthesis of quinoxaline-benzoxale conjugates and mesomorphic properties

A new series of non-discotic heterocyclic compounds 1a-e derived from quinoxaline was prepared and their mesomorphic properties investigated. The crystal and molecular structures of nonmesogenic 2,3-bis(3,4-didodecyloxyphenyl)quinoxaline-6-carboxylic acid 4-[(4-butoxy2-hydroxyphenylimino)methyl]phenyl ester 2a (n=4, m=12) were determined by means of X-ray structural analysis. It crystallizes in a monoclinic space group P2(1)/c, with a=21.9193(13) Å, b=8.3693(4) Å, c=30.896(2) Å, and Z=4. The molecule was considered as an elongated or tapered triangle. Both inter- and intra-molecular H-bonds were observed in the crystal lattice, which was attributed to the formation of columnar mesophase in compounds 2. The mesomorphic behavior of compounds 1-2 was studied by thermal analysis and polarized optical microscopy. All compounds 1-2 exhibited hexagonal columnar phases (Col_h), which were also confirmed by powder XRD diffractometer. A N_cell and R_ar value equal to 4.74 and 4.34 within a slice of 9.0 Å thick were obtained for 1b and 2b, indicating that a more disc-like correlated structure by two molecules lying side-by-side was formed in Col_h phases. The fluorescent properties of the compounds 1-4 in CH₃Cl were also examined.     

Catenar bimetallomesogens derived from quinoxaline–salicylaldimine conjugates

The preparation, characterization, and mesomorphic properties of two series of tridentate N-salicylidene-2-hydroxyanilines and their metal complexes were described. The crystal and molecular structure of bis[2-hydroxy-4-propyloxy-N-(2-hydroxy-3,4-dipropyloxybenzylidene) aniline]copper(II) were determined by means of X-ray analysis. It crystallizes in the monoclinic space group P2(1)/n and a Z=4. The geometry at Cu²⁺ ions is square pyramidal with a THF solvent molecule coordinated. The core structure was nearly flat, and the intramolecular Cu–Cu atoms were separated by ca. 3.0163(6) Å. All compounds 2a formed smectic C phases, and copper complexes 1a–Cu were not mesogenic. In contrast, compound 2e and complexes 1b–Cu, 1d–Cu, 1e–Cu, and 1e–Pd exhibited columnar phases. The lack of mesomorphism in 1e–Zn was attributed to a preferred tetrahedral over square planar geometry. A N_cell equal to 2.44–2.92, calculated from powder XRD data within a 9.0 Å thick indicated that an induced structure correlated by two catenar-shaped molecules was formed in Col_h phases.     

Polarization effects in mesogenic isoxazoles and 1,3,4-oxadiazoles

Four new series of unsymmetric isoxazoles and 1,3,4-oxadiazoles were prepared, characterized and their mesomorphic properties investigated. Isoxazoles were obtained by condensation–cyclization of β-diketones with hydroxylamine hydrochloride in refluxing THF, while 1,3,4-oxadiazoles were obtained from hydrazine-carboxylate in refluxing POCl₃. Two single crystallographic structures were determined by X-ray crystallographic analysis. A correlated dimeric structure was formed by H-bonds in isoxazoles 1a (n=6), leading to a more elongated structure required for the formation of mesophases. All compounds 1a–c formed N, SmA or/and SmC phases. In contrast, compounds 1d exhibited columnar phases, and an N_cell=14.6 obtained from powder XRD data indicated that a correlated structure formed by four molecules was probably induced in Col_h phases. The better mesomorphic behavior formed in 1a than 1b might be attributed to stronger intermolecular interactions and higher polarization induced in isoxazoles 1a.     

Calamitic metallomesogens derived from unsymmetric pyrazoles

Three series of copper(II) complexes 1a-1c derived from unsymmetric pyrazoles 2a-2c were prepared and their mesomorphic properties investigated. The mesomorphic behavior of compounds was studied by differential scanning calorimetry, polarizing optical microscopy, and powder X-ray diffractometry. The crystal and molecular structures of mesogenic copper complex (2a; n=10) of 3-[4-decyloxyphenyl]-1H-pyrazole were determined by means of X-ray structural analysis. It crystallizes in the triclinic space group P-1, with a=4.0890(1) Å, b=18.0167(2) Å, c=25.5015(5) Å, and Z=2. The geometry at copper center was not perfectly square planar. A weak intermolecular H-bond (d=2.36 Å) between Cl1 and H2 atoms and π-π interaction (ca. 3.45-3.55 Å) was also observed. All their precursors 2a-2c were not mesogenic. In contrast, copper complexes 1a formed nematic or smectic C phases and complexes 1b-1c formed crystalline phases. Powder X-ray diffraction experiments confirmed the presence of SmC phase.     

Phase transitions in K3AlF6

Phase transitions in the elpasolite-type K₃AlF₆ complex fluoride were investigated using differential scanning calorimetry, electron diffraction and X-ray powder diffraction. Three phase transitions were identified with critical temperatures , and . The α-K₃AlF₆ phase is stable below T₁ and crystallizes in a monoclinic unit cell with a=18.8588(2)Å, b=34.0278(2)Å, c=18.9231(1)Å, β=90.453(1)° (a=2a_c−c_c, b=4b_c, c=a_c+2c_c; a_c, b_c, c_c—the basic lattice vectors of the face-centered cubic elpasolite structure) and space group I2/a or Ia. The intermediate β phase exists only in very narrow temperature interval between T₁ and T₂. The γ polymorph is stable in the T₂<T<T₃ temperature range and has an orthorhombic unit cell with a=36.1229(6)Å, b=17.1114(3)Å, c=12.0502(3)Å (a=3a_c−3c_c, b=2b_c, c=a_c+c_c) at 250 °C and space group Fddd. Above T₃ the cubic δ polymorph forms with a_c=8.5786(4)Å at 400 °C and space group . The similarity between the K₃AlF₆ and K₃MoO₃F₃ compounds is discussed.     

Synthesis and structural, spectroscopic, and electrochemical characterization of benzo[c]quinolizinium and its 5-aza-, 6-aza, and 5,6-diaza analogues

Four heterocyclic salts 1a-d were prepared by Ca²⁺-assisted cyclization of fluoro derivatives 3, and investigated by spectroscopic (NMR and UV), electrochemical, and computational (DFT and MP2) methods. The mechanism for the formation of the cations was investigated at the DFT level of theory. 2-D NMR spectroscopy for 1[ClO₄] in DMSO­d₆ aided with DFT results permitted the assignment of ¹H and ¹³C NMR signals in cations 1. The molecular and crystal structures for 1a[ClO₄] [C₁₃H₁₀ClNO₄ triclinic, P−1, a=9.6517(12) Å, b=11.0470(13) Å, c=12.2373(15) Å, α=67.615(1)°, β=78.845(2)°, γ=87.559(2)°; V=1183.0(2) Å³, Z=4] and 1d[ClO₄] [C₁₂H₉ClN₂O₄ triclinic, P−1, a=5.9525(6) Å, b=8.3141(9) Å, c=12.2591(13) Å, α=73.487(1)°, β=83.814(1)°, γ=83.456(1)°; V=576.07(10) Å³, Z=2] were determined by X-ray crystallography and compared with results of DFT and MP2 calculations. Electrochemical analysis gave the reduction potential order (1b>1c∼1d>1a), which is consistent with computational results.     

Half-sandwich η-arene–ruthenium(II) complexes bearing 1-alkyl(benzyl)-imidazo[4,5-f][1,10]-phenanthroline (IP) derivatives: the effect of alkyl chain length of ligands to catalytic activity

The reaction of bromoalkanes (R–Br; (3), R=C_nH_2n+1, n=4 (a), 8 (b), 12 (c),18 (d)) and bromobenzyl derivatives (R′–Br; (4), R′=CH₂C₆H₂(CH₃)₃-2,4,6 (a); CH₂C₆H(CH₃)₄-2,3,5,6 (b); CH₂C₆(CH₃)₅ (c)) with 1H-imidazo[4,5-f][1,10]-phenanthroline (IP)(L₂) gave the corresponding 1-R-imidazo[4,5-f][1,10]-phenanthroline (IPR)(L_3a–d) and 1-R′-imidazo[4,5-f][1,10]-phenanthroline(IPR')(L_4a–c) ligands, respectively. Treatment of L_3a–d and L_4a–d with [Ru(p-cymene)Cl₂]₂ led to the formation of [Ru(p-cymene)(IPR)Cl]Cl (RuL_3a–d) and [Ru(p-cymene)(IPR′)Cl]Cl (RuL_4a–c). New ruthenium(II) complexes RuL_3a–d and RuL_4a–c were characterized by elemental analysis, FTIR, UV–visible and NMR spectroscopy. In order to understand effects of these changes on the N-substituent of imidazol on IP and how they translate to catalytic activity, these new RuL₂, RuL_3a–d and RuL_4a–c were applied in the transfer hydrogenation of ketones by 2-propanol in presence of potassium hydroxide. The activities of the catalysts were monitored by NMR and GC analysis.     

Synthesis of l-azaisotryptophan and its analogs: a general access to new 2-substituted azaindoles

l-(N-Cbz)-7-azaisotryptophan, l-(N-Cbz)-1a, a new isostere of tryptophan, was synthesized by reacting Li₂-(N-Boc)-2-amino-3-picoline, Li₂-(N-Boc)-2a, with appropriately protected l-aspartic acid followed by simple functional group manipulation. This synthetic success led us to access a set of analogs of azaisotryptophan (4a–c; 6a–c) as well as a new class of chiral amines (7a–c; 8a–c) for future application in asymmetric synthesis and design of homochiral ligands. Further, we have generalized the method substantiating a variety of new azaindol-2-yl derivatives (10aa–10lc) with functionalized substituents. In a preliminary luminescence characterization, l-(N-Cbz)-1a has exhibited about 30 nm bathochromic shifted fluorescence emission compared to tryptophan and (N-Cbz)-tryptophan.     

An unexpected formation of pyrazolopyrimidines during the attempted to obtain 5-substituted tetrazoles from carbonitriles

In this Letter, we described the synthesis of new 5-(5-amino-1-aryl-1H-pyrazole-4-yl)-1H-tetrazoles 2a–c from 5-amino-1-aryl-1H-pyrazole-4-carbonitriles 1a–c as well as the unexpected 1H-pyrazolo[3,4-d]pyrimidine derivatives 6a–c from 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles 4a–c, instead of 5-(5-amino-1-aryl-3-methyl-1H-pyrazole-4-yl)-1H-tetrazoles 5a–c as desired. In an attempt to obtain these tetrazole derivatives containing the methyl group at C3-position in the pyrazole ring, the amino group in 5-amino-1-(4-methoxyphenyl)-3-methyl-1H-pyrazole-4-carbonitrile 4c was protected by the reaction with sodium hydride and di-tert-butyl-dicarbonate (Boc). The tetrazole derivative 5c was synthesized from the protected compound 7c using analogue methodology to obtain 2a–c and 6a–c.     

H-Bonded metallomesogens: preparation, characterization, and mesomorphic studies of (3-hydroxypropylimino)propan-1,2-diols

Two series of new Schiff bases 2 (n=8, 12, 16) derived from (3-hydroxypropyl imino)propan-1, 2-diol with a hydroxyl group at C₁₉/C₂₀-position and their palladium complexes 1 were prepared and their mesomorphic properties investigated by DSC, POM, and XRD. The presence of both hydroxyl groups was found to be crucial in forming the liquid crystalline behavior. All compounds 2a exhibited smectic A or and C phases, in contrast, all compounds 2b formed hexagonal columnar phases. The formation of mesophases in both compounds 1-2 was probably induced by inter-molecular H-bonds. Single crystallographic data in mesogenic compound 2a (n=8) indicated that a dimeric structure with a better linear or rod-like molecular shape was formed by an inter-molecular H-bond (O4-O1′, ∼1.854 Å). Another inter-molecular H-bond (∼1.903 Å) between two dimeric structures was also observed. It crystallizes in a monoclinic space group P2(1)/c. On the other hand, all palladium complexes 1 formed enantiotropic smectic A phases. Single crystallographic data in mesogenic compound 1a (n=8) indicated that the geometry at Pd²⁺ center was coordinated as slightly twisted square planar. It crystallizes in a monoclinic space group P2(1)/n. An inter-molecular H-bond (∼1.799 Å) between neighboring molecules were observed, which might have facilitated the formation of mesophases. Variable-temperature powder XRD experiments confirmed their mesophase structures.     

A novel and easy two-step,microwave-assisted method for the synthesis of halophenyl pyrrolo[2,3-b]quinoxalines via their pyrrolo precursors. Evaluation of their bioactivity

A novel, two-step, facile route for the synthesis of pyrrolo[2,3-b]quinoxalines via 2,3-dioxopyrroles, enhanced by microwave irradiation, is presented. The newly synthesized 2,3-dioxo-5-halophenyl pyrrolo precursors 4a–c as well as the non-aromatized ethyl 2-(4-halophenyl)-1-methyl-2,4-dihydro-1H-pyrrolo[2,3-b]quinoxaline-3-carboxylates 6a–c and the aromatized ethyl 2-(4-halophenyl)-1-methyl-1H-pyrrolo[2,3-b]quinoxaline-3-carboxylates 7a–c were evaluated for their antioxidant, cytostatic, and antiviral properties. Most of them proved to be potent hydroxyl radical scavengers and inhibited in vitro lipid peroxidation. The compounds showed moderate antiproliferative activity, while 6a inhibited vaccinia virus at an EC₅₀ value of 2 μM, and 4c and 6c inhibited Sindbis virus at EC₅₀ values of 4 μM.     

Phosphorus–nitrogen compounds: Part 19. Syntheses,structural and electrochemical investigations,biological activities,and DNA interactions of new spirocyclic monoferrocenylcyclotriphosphazenes

The reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆, with N-alkyl-N-ferrocenylmethylethylene diamines, FcCH₂NH(CH₂)₂NHR₁ [R₁ = Me (1) and Et (2)], and sodium [3-(N-ferrocenylmethylamino)-1-propanoxide] (3) produce spirocyclic monoferrocenyl tetrachlorophosphazenes (1a–3a). The tetrapyrrolidinophosphazenes (1b–3b) are prepared from the reactions of corresponding phosphazenes (1a–3a) with excess pyrrolidine. The reaction of 1a with excess morpholine affords geminal-morpholino phosphazene (1c), whilst the reactions of 2a and 3a give diethylaminotrimorpholino (2c) and fully substituted morpholino products (3c), respectively. The structural investigations of the compounds are examined by Fourier transform IR, MS, ¹H, ¹³C, ³¹P NMR, DEPT, HETCOR, and HMBC techniques. The crystal structures of 3b and 3c are determined using X-ray crystallography. Cyclic voltammetric and chronoamperometric data show that compounds 1a–3a, 1b–3b, and 1c–3c exhibit electrochemically reversible one-electron oxidation of Fc redox centers which are hardly affected by the substituents on the phosphazene ring. The compounds 1b, 2b, 3b, and 3c are screened for antibacterial activities against Gram-positive and Gram-negative bacteria and for antifungal activities against yeast strains. In addition, the antituberculosis activities (in vitro) of these compounds are evaluated against INH-susceptible reference strain M. tuberculosis H37Rv, and six multi-drug resistant clinical M. tuberculosis isolates. Compound 2b is found to be the most active against the susceptible the reference strain. In addition, 1b, 2b, and 3c are active against all the multidrug-resistant clinical isolates at the highest concentrations. Gel electrophoresis data indicate that the compounds promote the formation of strand breaks in plasmid DNA. Almost all the concentrations lost of supercoiled DNA suggests that the compound 3b is very efficient plasmid-modifier. The compounds inhibit BamHI cleavage of pUC18 DNA while restricting HindIII.     

New cyano-substituted organic dyes containing different electrophilic groups: aggregation-induced emission and large two-photon absorption cross section

Three aggregation-induced emission active dyes (3a–c) were synthesized and their one- and two-photon absorption properties have been investigated. They were all found to be weakly fluorescent in THF solution, while they exhibited dramatic fluorescence enhancement in water/THF mixtures. The solid fluorescence of 3a–c was recorded and their fluorescence quantum efficiency (Φ_F) values were determined to be 8.0%, 8.1%, and 16.4%, respectively. Moreover, the two-photon absorption (2PA) cross-sections (σ) of 3a–c were measured and 3a showed the highest value of 702 GM. The excellent aggregation-induced emission and 2PA properties provide a promising alternative for biophotonic materials.     

Synthesis and molecular structures of dinuclear complexes with 1,2-dihydro-1,2-diphenyl-naphtho[1,8-c,d]1,2-diphosphole as a bridging ligand

A bisphosphine in which a PhP-PPh bond bridges 1,8-positions of naphthalene, 1,2-dihydro-1,2-diphenyl-naphtho[1,8-cd]-1,2-diphosphole (1), was used as a bridging ligand for the preparation of dinuclear group 6 metal complexes. Free trans-1, a more stable isomer having two phenyl groups on phosphorus centers mutually trans with respect to a naphthalene plane, was allowed to react with two equivalents of M(CO)₅(thf) (M = W, Mo, Cr) at room temperature to give dinuclear complexes (OC)₅M(μ-trans-1)M(CO)₅ (M = W (2a), Mo (2b), Cr (2c)). The preparation of the corresponding dinuclear complexes bridged by the cis isomer of 1 was also carried out starting from the free trans-1 in the following way. Mono-nuclear complexes M(trans-1)(CO)₅ (M = W (3a), Mo (3b), Cr (3c)) which had been prepared by a reaction of trans-1 with one equivalent of the corresponding M(CO)₅(thf) (M = W, Mo, Cr) complex, were heated in toluene, wherein a part of the trans-3a-c was converted to their respective cis isomer M(cis-1)(CO)₅. Each cis trans mixture of the mono-nuclear complexes 3a-c was treated with the corresponding M(CO)₅(thf) to give a cis trans mixture of the respective dinuclear complexes 2a-c. The cis isomer of the ditungsten complex 2a was isolated, and its molecular structure was confirmed by X-ray analysis, showing a shorter W?W distance of 5.1661(3) Å than that of 5.8317(2) Å in trans-2a.     

Conjugated C3 symmetric aryl tripyrroles and aryl bipyrroles: synthesis,optical and electronic properties

Conjugated C₃ symmetric molecules have been pursued for their fluorescent and electrochemical properties. The synthesis of conjugated C₃ symmetric aryl tripyrroles has been performed by a route featuring three steps from trimethyl 1,3,5-benzene tricarboxylate 6: copper-catalyzed cascade addition of vinylmagnesium bromide to convert the carboxylates into γ,δ-unsaturated ketones, Tsuji–Wacker olefin oxidations to form tris(1,4-dione) 9, and Paal–Knorr condensation with ammonia and different amines to furnish the final tripyrroles (30–60% yields). In addition, incomplete reaction of vinylmagnesium bromide to 6 provided benzoate 8 possessing two γ,δ-unsaturated ketones, which were similarly converted to 3,5-dipyrrolylbenzoates 11. The absolute fluorescence quantum yields (Φ_fl) and electrochemical properties of 5a–c and 11a–c were investigated. The Φ_fl are the first reported for such compounds and they ranged between 2 and 40%, contingent on structure and solvent polarity. Cyclic voltammetry revealed that the compounds could be both oxidized and reduced, albeit irreversibly. The oxidation potentials (E_ox) varied between 0.73 V and 1.2 V and the reduction potentials (E_red) varied from −0.83 V to −1.36 V. The lowest redox processes were measured for the NH–pyrrole 5a. Moreover, tripyrrole 5a was air stable and on oxidative doping with ferric chloride exhibited a 50 nm bathochromic shift in its absorbance spectrum.     

New star-shaped triarylamines: synthesis, mesomorphic behavior, and photophysical properties

A total of 18 compounds 1-6 derived from triphenylamine as core group were prepared and characterized, and their mesomorphic properties were also investigated. Compounds 1-4 and 5,6 were prepared from p,p′,p″-triformyltriphenylamine and p,p′-diformyltriphenylamine with appropriate alkoxyphenylamines. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimetry, polarized optical microscopy, and powder XRD diffraction. Compounds 1-3 exhibited columnar mesophase, however, compounds 4-6 were nonmesogenic. The mesophases observed in compounds 1-3 were found to be side dependent. Compounds 1a, 2a, and 3a appended with one, two, or three side chains exhibited lamellar columnar (Col_L) phases, and compounds 2b and 3b with four or six side chains formed hexagonal columnar (Col_h) phases. The formation of the mesophases, lamellar or columnar mesophases, was probably induced by H-bonding formed between -CH₂NH groups. The oxidation process determined by cyclic voltammetry showed two redox waves, one appeared at 220-255 mV and the other one at 503-677 mV, which gave energy to HOMOs range of 5.02-5.36 eV. The fluorescent properties of the compounds were examined. All λ_max peaks of the absorption and photoluminescence spectra of compounds occurred at ca. 307-392 nm and 368-456 nm, respectively. Compound 4a has a larger red shift due to a better conjugation linked by CC double bonds instead of -CH₂NH in other compounds.     

Hydrothermal syntheses and structures of the uranyl tellurates AgUO2(HTeO5) and Pb2UO2(TeO6)

Two uranyl tellurates, AgUO₂(HTeO₅) (1) and Pb₂UO₂(TeO₆) (2), were synthesized under hydrothermal conditions and were structurally, chemically, and spectroscopically characterized. 1 crystallizes in space group Pbca, a=7.085(2) Å, b=11.986(3) Å, c=13.913(4) Å, V=1181.5(5) Å³, Z=8; 2 is in P2(1)/c, a=5.742(1) Å, b=7.789(2) Å, c=7.928(2) Å, V=90.703(2) Å³, and Z=2. These are the first structures reported for uranyl compounds containing tellurate. The U⁶⁺ cations are present as (UO₂)²⁺ uranyl ions that are coordinated by O atoms to give pentagonal and square bipyramids in compounds 1 and 2, respectively. The structural unit in 1 is a sheet consisting of chains of edge-sharing uranyl pentagonal bipyramids that are one bipyramid wide, linked through the dimers of TeO₆ octahedra. In 2, uranyl square bipyramids share each of their equatorial vertices with different TeO₆ octahedra, giving a sheet with the autunite-type topology. Sheets in 1 and 2 are connected through the low-valence cations that are located in the interlayer region. The structures of 1 and 2 are compared to those of uranyl compounds containing octahedrally coordinated cations.     

A facile approach for the synthesis of novel substituted 4H-chromenes and condensation reactions of 4H-chromenes leading to chromenopyrrolones and triazolylchromenopyrrolones

A facile method has been developed for the synthesis of 4H-chromene-3-carboxylates 3a–d by the nucleophilic substitution reaction of 2-hydroxy-2H-chromene-3-carboxylates 2a–d with triethylsilane in the presence of BF₃·O(C₂H₅)₂. Cyclocondensation of 4H-chromene-3-carboxylates 3a–d with benzylamines 4a–d afforded a series of 2,3-dihydrochromenopyrrolones 5a–p and with propargylamine afforded 2-propynyl-2,3-dihydrochromenopyrrolones 6a–d. Click reaction of 6a–d with benzyl azides 7a–d provided a series of 1H-1,2,3-triazolylmethyl-2,3-dihydrochromenopyrrolones 8a–p. Thus synthesized compounds 3a–d, 5a–p, 6a–d, and 8a–p are novel heterocyclic compounds and being reported for the first time.