Hydrogen‐bonding patterns in enaminones: (2Z)‐1‐(4‐bromophenyl)‐2‐(pyrrolidin‐2‐ylidene)ethanone and its piperidin‐2‐ylidene and azepan‐2‐ylidene analogues

The title compounds, namely (2Z)‐1‐(4‐bromophenyl)‐2‐(pyrrolidin‐2‐ylidene)ethanone, C₁₂H₁₂BrNO, (I), (2Z)‐1‐(4‐bromophenyl)‐2‐(piperidin‐2‐ylidene)ethanone, C₁₃H₁₄BrNO, (II), and (2Z)‐2‐(azepan‐2‐ylidene)‐1‐(4‐bromophenyl)ethanone, C₁₄H₁₆BrNO, (III), are characterized by bifurcated intra‐ and intermolecular hydrogen bonding between the secondary amine and carbonyl groups. The former establishes a six‐membered hydrogen‐bonded ring, while the latter leads to the formation of centrosymmetric dimers. Weak C—H...Br interactions link the individual molecules into chains that run along the [011], [101] and [101] directions in (I)–(III), respectively. Additional weak Br...O, C—H...π and C—H...O interactions further stabilize the crystal structures.     

Synthesis of 6‐Aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles by the Cu‐Catalyzed Reaction of 2‐(2‐Bromophenyl)‐1H‐indoles with CH2(CN)2

A series of 6‐aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles 4 have been prepared by treatment of 2‐(2‐bromophenyl)‐1H‐indoles 1 , available from 1‐(2‐bromophenyl)ethanones or 1‐(2‐bromophenyl)propan‐1‐ones by using Fischer indole synthesis, with propanedinitrile in the presence of a catalytic amount of CuBr and an excess of K₂CO₃ in DMSO at 100°.     

π‐stacking and C—X...D (X = H,NO2; D = O, π) interactions in the crystal network of both C—H...N and π‐stacked dimers of 1,2‐bis(4‐bromophenyl)‐1H‐benzimidazole and 2‐(4‐bromophenyl)‐1‐(4‐nitrophenyl)‐1H‐benzimidazole

Molecules of 1,2‐bis(4‐bromophenyl)‐1H‐benzimidazole, C₁₉H₁₂Br₂N₂, (I), and 2‐(4‐bromophenyl)‐1‐(4‐nitrophenyl)‐1H‐benzimidazole, C₁₉H₁₂BrN₃O₂, (II), are arranged in dimeric units through C—H...N and parallel‐displaced π‐stacking interactions favoured by the appropriate disposition of N‐ and C‐bonded phenyl rings with respect to the mean benzimidazole plane. The molecular packing of the dimers of (I) and (II) arises by the concurrence of a diverse set of weak intermolecular C—X...D (X = H, NO₂; D = O, π) interactions.     

Synthesis of a soluble conjugated cumulene polymer: poly(biphenyl‐4,4′‐diyl‐1,4‐bis(4‐dodecyloxyphenyl)‐buta‐1,2,3‐triene‐1,4‐diyl)

A conjugated polymer with a butatriene segment in the main chain, poly(biphenyl‐4,4′‐diyl‐1,4‐bis(4‐dodecyloxyphenyl)buta‐1,2,3‐triene‐1,4‐diyl), was synthesized from 1,4‐bis(4‐bromophenyl)‐1,4‐bis(4‐dodecyloxyphenyl)buta‐1,2,3‐triene by dehalogenative polycondensation using Ni(cod)₂. The polymer was well soluble in usual organic solvents such as CHCl₃ and THF. Structural analyses and characterizations were carried out by IR, NMR, UV‐Vis, PL, and Raman spectroscopy, as well as electrical conductivity. It is suggested that π‐conjugation is extended to some degree through biphenylylene and butatrienylene linkages.     

Stereocomplementary Synthesis of cis‐ and trans‐2‐(p‐Bromophenyl)‐5‐methylthiazolidin‐4‐ones: Useful Umpolung‐type Suzuki–Miyaura Cross‐coupling Partner and Donor

Novel cis‐ and trans‐2‐(p‐bromophenyl)‐5‐methylthiazolidin‐4‐ones, S,N‐containing heterocyclic compounds, were provided in a cis‐stereocomplementary and trans‐stereocomplementary synthetic manner. cis‐Selective cyclo‐condensation proceeded between 2‐sulfanylpropanoic acid (thiolactic acid) and an imine derived from 4‐bromobenzaldehyde and methylamine, whereas Ti(OiPr)₄ and Ti(OiBu)₄‐promoted trans‐selective cyclo‐condensation proceeded between benzyl 2‐sulfanylpropanoate and the imine. The obtained cis‐ and trans ‐ 2‐(p‐bromophenyl)‐5‐methylthiazolidin‐4‐ones were successfully converted to 2‐(3‐furyl)phenyl derivatives and bis(pinacolato)diborane derivatives utilizing Suzuki–Miyaura and Miyaura–Ishiyama cross‐coupling reactions, respectively, in an umpolung manner.     

4‐Styrylquinolines from cyclocondensation reactions between (2‐aminophenyl)chalcones and 1,3‐diketones: crystal structures and regiochemistry

Structures are reported for two matched sets of substituted 4‐styrylquinolines which were prepared by the formation of the heterocyclic ring in cyclocondensation reactions between 1‐(2‐aminophenyl)‐3‐arylprop‐2‐en‐1‐ones with 1,3‐dicarbonyl compounds. (E)‐3‐Acetyl‐4‐[2‐(4‐methoxyphenyl)ethenyl]‐2‐methylquinoline, C₂₁H₁₉NO₂, (I), (E)‐3‐acetyl‐4‐[2‐(4‐bromophenyl)ethenyl]‐2‐methylquinoline, C₂₀H₁₆BrNO, (II), and (E)‐3‐acetyl‐2‐methyl‐4‐{2‐[4‐(trifluoromethyl)phenyl]ethenyl}quinoline, C₂₁H₁₆F₃NO, (III), are isomorphous and in each structure the molecules are linked by a single C—H…O hydrogen bond to form C(6) chains. In (I), but not in (II) or (III), this is augmented by a C—H…π(arene) hydrogen bond to form a chain of rings; hence, (I)–(III) are not strictly isostructural. By contrast with (I)–(III), no two of ethyl (E)‐4‐[2‐(4‐methoxyphenyl)ethenyl]‐2‐methylquinoline‐3‐carboxylate, C₂₂H₂₁NO₃, (IV), ethyl (E)‐4‐[2‐(4‐bromophenyl)ethenyl]‐2‐methylquinoline‐3‐carboxylate, C₂₁H₁₈BrNO₂, (V), and ethyl (E)‐2‐methyl‐4‐{2‐[4‐(trifluoromethyl)phenyl]ethenyl}quinoline‐3‐carboxylate, C₂₂H₁₈F₃NO₂, (VI), are isomorphous. The molecules of (IV) are linked by a single C—H…O hydrogen bond to form C(13) chains, but cyclic centrosymmetric dimers are formed in both (V) and (VI). The dimer in (V) contains a C—H…π(pyridyl) hydrogen bond, while that in (VI) contains two independent C—H…O hydrogen bonds. Comparisons are made with some related structures, and both the regiochemistry and the mechanism of the heterocyclic ring formation are discussed.     

The absolute configuration of (2S,4S)‐ and (2R,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolyl­sulfon­yl)‐1,3‐oxazolidine‐4‐carbaldehyde

The title enanti­omorphic compounds, C₁₆H₂₃NO₄S, have been obtained in an enanti­omerically pure form by crystallization from a diastereomeric mixture either of (2S,4S)‐ and (2R,4S)‐ or of (2R,4R)‐ and (2S,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolyl­sulfon­yl)‐1,3‐oxazolidine‐4‐carbaldehyde. These mixtures were prepared by an aziridination rearrangement process starting with (S)‐ or (R)‐2‐tert‐butyl‐5‐methyl‐4H‐1,3‐dioxine. The crystal structures indicate an envelope conformation of the oxazolidine moiety for both compounds.     

Bis(acesulfamato‐κ2N3,O4)bis­(2‐amino­pyrimidine‐κN1)copper(II)

In the crystal structure of the title compound, bis­(2‐amino­pyrimidine‐κN¹)bis­[6‐meth­yl‐1,2,3‐oxathia­zin‐4(3H)‐one 2,2‐dioxide(1−)‐κ²N³,O⁴]copper(II), [Cu(C₄H₄NO₄S)₂(C₄H₅N₃)₂], the first mixed‐ligand complex of acesulfame, the Cu^II centre resides on a centre of symmetry and has an octa­hedral geometry that is distorted both by the presence of four‐membered chelate rings and by the Jahn–Teller effect. The equatorial plane is formed by the N atoms of two amino­pyrimidine (ampym) ligands and by the weakly basic carbonyl O atoms of the acesulfamate ligands, while the more basic deprotonated N atoms of these ligands are in the elongated axial positions with a strong misdirected valence. The crystal is stabilized by pyrimidine ring stacking and by inter­molecular hydrogen bonding involving the NH₂ moiety of the ampym ligand and the carbon­yl O atom of the acesulfamate moiety.     

(E)‐(4‐Hydroxyphenyl)(4‐nitrophenyl)diazene, (E)‐(4‐methoxyphenyl)(4‐nitrophenyl)diazene and (E)‐[4‐(6‐bromohexyloxy)phenyl](4‐cyanophenyl)diazene

Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₂H₉N₃O₃, (Ia), (E)‐(4‐methoxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₃H₁₁N₃O₃, (IIIa), and (E)‐[4‐(6‐bromo­hexyl­oxy)­phenyl](4‐cyano­phenyl)­diazene, C₁₉H₂₀BrN₃O, (IIIc). In all of these compounds, the mol­ecules are almost planar and the azo­benzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent mol­ecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent mol­ecules are almost identical, whereas in crystal (IIIc), the two independent mol­ecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the mol­ecules are arranged in almost planar sheets. In the crystal of (IIIc), the mol­ecules are packed with a marked separation of the azo­benzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens.     

Solvatomorphism in (E)‐2‐(2,6‐dichloro‐4‐hydroxybenzylidene)hydrazinecarboximidamide

The structures of orthorhombic (E)‐4‐(2‐{[amino(iminio)methyl]amino}vinyl)‐3,5‐dichlorophenolate dihydrate, C₈H₈Cl₂N₄O·2H₂O, (I), triclinic (E)‐4‐(2‐{[amino(iminio)methyl]amino}vinyl)‐3,5‐dichlorophenolate methanol disolvate, C₈H₈Cl₂N₄O·2CH₄O, (II), and orthorhombic (E)‐amino[(2,6‐dichloro‐4‐hydroxystyryl)amino]methaniminium acetate, C₈H₉Cl₂N₄O⁺·C₂H₃O₂⁻, (III), all crystallize with one formula unit in the asymmetric unit, with the molecule in an E configuration and the phenol H atom transferred to the guanidine N atom. Although the molecules of the title compounds form extended chains via hydrogen bonding in all three forms, owing to the presence of different solvent molecules, those chains are connected differently in the individual forms. In (II), the molecules are all coplanar, while in (I) and (III), adjacent molecules are tilted relative to one another to varying degrees. Also, because of the variation in hydrogen‐bond‐formation ability of the solvents, the hydrogen‐bonding arrangements vary in the three forms.     

Identification of (6R)‐5,6,7,8‐Tetrahydro‐D‐monapterin (=(6R)‐2‐Amino‐5,6,7,8‐tetrahydro‐6‐[(1R,2R)‐1,2,3 ‐trihydroxypropyl]pteridin‐4(3H)‐one) as the Native Pteridine in Tetrahymena pyriformis

The structure of the native pteridine in Tetrahymena pyriformis was determined as (6R)‐5,6,7,8‐tetrahydro‐D ‐monapterin (=(6R)‐2‐amino‐5,6,7,8‐tetrahydro‐6‐[(1R,2R)‐1,2,3‐trihydroxypropyl]pteridin‐4(3H)‐one; 4 ). First, the configuration of the 1,2,3‐trihydroxypropyl side chain was confirmed as D ‐threo by the fluorescence‐detected circular dichroism (FDCD) spectrum of its aromatic pterin derivative 2 obtained by I₂ oxidation (Fig. 1). The configuration at the 6‐position of 4 was determined as (R) by comparison of its hexaacetyl derivative 6 with authentic (6R)‐ and (6S)‐hexaacetyl‐5,6,7,8‐tetrahydro‐D ‐monapterins 6 and 7 , respectively, in the HPLC, LC/MS, and LC‐MS/MS (Figs. 3 – 6). (6R)‐5,6,7,8‐Tetrahydro‐D ‐monapterin ( 4 ) is a newly discovered natural tetrahydropterin.     

(1R,2R)‐2‐(4‐Methylenecyclohex‐2‐enyl)propyl (1R,4S)‐camphanate

Esterification of a single diastereomer of 2‐(4‐methylene­cyclohex‐2‐enyl)propanol, (II), with (1R,4S)‐(+)‐camphanic acid [(1R,4S)‐4,7,7‐trimethyl‐3‐oxo‐2‐oxabicyclo[2.2.1]heptane‐1‐carboxylic acid] leads to the crystalline title compound, C₂₀H₂₈O₄. The relative configuration of the camphanate was determined by X‐ray diffraction analysis. The outcome clarifies the relative and absolute stereochemistry of the naturally occurring bisabolane sesquiterpenes β‐turmerone and β‐sesquiphellandrene, since we have converted (II) into both natural products via a stereospecific route.     

Synthesis of Novel Heterocyclic Compounds with Expected Antibacterial Activities from 4‐(4‐Bromophenyl)‐4‐oxobut‐2‐enoic Acid

This research describes the utility of 4‐(4‐bromophenyl)‐4‐oxobut‐2‐enoic acid as a key starting material for preparation of a novel series of aroylacrylic acids, pyridazinones, and furanones derivatives. These heterocyclic compounds were synthesized by reaction of 4‐(4‐bromophenyl)‐4‐oxobut‐2‐enoic acid with benzimidazole, ethyl glycinate hydrochloride, anthranilic acid and o‐phenylenediamine under Aza–Michael addition conditions. Every Aza–Michael adduct was allowed to react with haydrazine hydrate and acetic anhydride to form pyridazinones and furanones derivatives, respectively. In further step, some pyridazinones were allowed to react with ethyl acetoacetate, acetyl acetone, acetyl chloride, and aromatic aldehydes to form novel heterocylces. Finally, studying antibacterial activities of these compounds was performed.     

ZnII and CuII complexes generated from 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione

A new 1,3,4‐oxadiazole‐containing bispyridyl ligand, namely 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione (L), has been used to create the novel complexes tetranitratobis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}zinc(II), [Zn₂(NO₃)₄(C₁₄H₁₂N₄OS)₂], (I), and catena‐poly[[[dinitratocopper(II)]‐bis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}] nitrate acetonitrile sesquisolvate dichloromethane sesquisolvate], {[Cu(NO₃)(C₁₄H₁₂N₄OS)₂]NO₃·1.5CH₃CN·1.5CH₂Cl₂}_n, (II). Compound (I) presents a distorted rectangular centrosymmetric Zn₂L₂ ring (dimensions 9.56 × 7.06 Å), where each Zn^II centre lies in a {ZnN₂O₄} coordination environment. These binuclear zinc metallocycles are linked into a two‐dimensional network through nonclassical C—H...O hydrogen bonds. The resulting sheets lie parallel to the ac plane. Compound (II), which crystallizes as a nonmerohedral twin, is a coordination polymer with double chains of Cu^II centres linked by bridging L ligands, propagating parallel to the crystallographic a axis. The Cu^II centres adopt a distorted square‐pyramidal CuN₄O coordination environment with apical O atoms. The chains in (II) are interlinked via two kinds of π–π stacking interactions along [01]. In addition, the structure of (II) contains channels parallel to the crystallographic a direction. The guest components in these channels consist of dichloromethane and acetonitrile solvent molecules and uncoordinated nitrate anions.     

Bis(acesulfamato‐κ2O4,N)bis­(3‐methyl­pyridine)copper(II)

In the crystal structure of the title compound {systematic name: bis­[6‐methyl‐1,2,3‐oxa­thia­zin‐4(3H)‐one 2,2‐dioxide(1−)‐κ²N³,O⁴]bis­(3‐meth­yl­pyridine)copper(II)}, [Cu(C₄H₄NO₄S)₂(C₆H₇N)₂], the Cu^II centre resides on a centre of symmetry and has an octa­hedral geometry that is distorted both by the presence of four‐membered chelate rings and because of the Jahn–Teller effect. The equatorial plane is formed by the N atoms of two methyl­pyridine ligands and by the more basic O atoms of the acesulfamate ligands, while the weakly basic N atoms of these ligands are in elongated axial positions with a misdirected valence. The crystal is stabilized by two inter­molecular C—H⋯O inter­actions involving the methyl and CH groups, and the sulfonyl O atoms of the acesulfamate group.     

Two (E)‐2‐({[4‐(dialkylamino)phenyl]imino}methyl)‐4‐nitrophenols

The slow evaporation of analytical NMR samples resulted in the formation of crystals of (E)‐2‐({[4‐(dimethylamino)phenyl]imino}methyl)‐4‐nitrophenol, C₁₅H₁₅N₃O₃, (I), and (E)‐2‐({[4‐(diethylamino)phenyl]imino}methyl)‐4‐nitrophenol, C₁₇H₁₉N₃O₃, (II). Despite the small structural difference between these two N‐salicylideneaniline derivatives, they show different space groups and diverse molecular packing. The molecules of both compounds are close to being planar due to an intramolecular O—H...N hydrogen bond. The 4‐alkylamino‐substituted benzene ring is inclined at an angle of 13.44 (19)° in (I) and 2.57 (8)° in (II) with respect to the 4‐nitro‐substituted phenol ring. Only very weak intermolecular π–π stacking and C—H...O interactions were found in these structures.     

Bis(acesulfamato‐κO4)diaqua­bis­(3‐methyl­pyridine‐κN)nickel(II)

In the crystal structure of the title compound [systematic name: diaqua­bis(6‐methyl‐2,2‐dioxo‐1,2,3‐oxathia­zin‐4‐olato‐κO⁴)bis­(3‐methyl­pyridine‐κN)nickel(II)], [Ni(C₄H₄NO₄S)₂(C₆H₇N)₂(H₂O)₂], the Ni^II centre resides on a centre of symmetry and has a distorted octa­hedral geometry. The basal plane is formed by two carbonyl O atoms of two monodentate trans‐oriented acesulfamate ligands and two trans aqua ligands. The axial positions in the octa­hedron are occupied by two N atoms of two trans pyridine ligands. Mol­ecules are stacked in columns running along the a axis. There are π–π stacking inter­actions between the mol­ecules in each column, with a distance of 3.623 (2) Å between the centroids of the pyridine rings. There are also O—H⋯O inter­actions between the columns.     

Stereoselective Synthesis of (Z)‐4‐(2‐Bromovinyl)benzene‐sulfonyl Azide and Its Synthetic Utility for the Transformation to (Z)‐N‐[4‐(2‐Bromovinyl)benzenesulfonyl]imidates

A novel method for the stereoselective synthesis of (Z)‐4‐(2‐bromovinyl)benzenesulfonyl azide by simultaneous azidation and debrominative decarboxylation of anti‐2,3‐dibromo‐3‐(4‐chlorosulfonylphenyl)propanoic acid using NaN₃ only was developed. Facile transformation of (Z)‐4‐(2‐bromovinyl)benzenesulfonyl azide to (Z)‐N‐[4‐ (2‐bromovinyl)benzenesulfonyl]imidates was also achieved by Cu‐catalyzed three‐component coulping of (Z)‐4‐(2‐bromovinyl)benzenesulfonyl azide, terminal alkynes and alcohols/phenols.     

Conformational study of (Z)‐5‐(4‐chlorobenzylidene)‐2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]‐3H‐imidazol‐4(5H)‐one in different environments: insight into the structural properties of bacterial efflux pump inhibitors

The 2‐amine derivatives of 5‐arylidene‐3H‐imidazol‐4(5H )‐one are a new class of bacterial efflux pump inhibitors, the chemical compounds that are able to restore antibiotic efficacy against multidrug resistant bacteria. 5‐Arylidene‐3H‐imidazol‐4(5H )‐ones with a piperazine ring at position 2 reverse the mechanisms of multidrug resistance (MDR) of the particularly dangerous Gram‐negative bacteria E. coli by inhibition of the efflux pump AcrA/AcrB/TolC (a main multidrug resistance mechanism in Gram‐negative bacteria, consisting of a membrane fusion protein, AcrA, a Resistant‐Nodulation‐Division protein, AcrB, and an outer membrane factor, TolC). In order to study the influence of the environment on the conformation of (Z )‐5‐(4‐chlorobenzylidene)‐2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]‐3H‐imidazol‐4(5H )‐one, ( 3 ), two different salts were prepared, namely with picolinic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium pyridine‐2‐carboxylate, C₁₆H₂₀ClN₄O₂⁺·C₆H₄NO₂⁻, ( 3 a )} and 4‐nitrophenylacetic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium 2‐(4‐nitrophenyl)acetate, C₁₆H₂₀ClN₄O₂⁺·C₈H₆NO₄⁻, ( 3 b )}. The crystal structures of the new salts were determined by X‐ray diffraction. In both crystal structures, the molecule of ( 3 ) is protonated at an N atom of the piperazine ring by proton transfer from the corresponding acid. The carboxylate group of picolinate engages in hydrogen bonds with three molecules of the cation of ( 3 ), whereas the carboxylate group of 4‐nitrophenylacetate engages in hydrogen bonds with only two molecules of ( 3 ). As a consequence of these interactions, different orientations of the hydroxyethyl group of ( 3 ) are observed. The crystal structures are additionally stabilized by both C—H…N [in ( 3 a )] and C—H…O [in ( 3 a ) and ( 3 b )] intermolecular interactions. The geometry of the imidazolone fragment was compared with other crystal structures possessing this moiety. The tautomer observed in the crystal structures presented here, namely 3H‐imidazol‐4(5H )‐one [systematic name: 1H‐imidazol‐5(4H )‐one], is also that most frequently observed in other structures containing this heterocycle.     

A series of substituted (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐phenylprop‐2‐en‐1‐ones

In the molecular structures of a series of substituted chalcones, namely (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐phenylprop‐2‐en‐1‐one, C₂₁H₁₅FO₂, (I), (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐fluorophenyl)prop‐2‐en‐1‐one, C₂₁H₁₄F₂O₂, (II), (2E)‐1‐(4‐chlorophenyl)‐3‐(2‐fluoro‐4‐phenoxyphenyl)prop‐2‐en‐1‐one, C₂₁H₁₄ClFO₂, (III), (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐methylphenyl)prop‐2‐en‐1‐one, C₂₂H₁₇FO₂, (IV), and (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐methoxyphenyl)prop‐2‐en‐1‐one, C₂₂H₁₇FO₃, (V), the configuration of the keto group with respect to the olefinic double bond is s‐cis. The molecules pack utilizing weak C—H...O and C—H...π intermolecular contacts. Identical packing motifs involving C—H...O interactions, forming both chains and dimers, along with C—H...π dimers and π–π aromatic interactions are observed in the fluoro, chloro and methyl derivatives.