Calcium Hydride Catalyzed Highly 1,2‐Selective Pyridine Hydrosilylation

Reaction of the calcium hydride complex (DIPPnacnac‐CaH?THF)₂ with pyridine is much faster and selective than that of the corresponding magnesium hydride complex (DIPPnacnac = [(2,6‐iPr₂C₆H₃)NC(Me)]₂CH). With a range of pyridine, picoline and quinoline substrates, exclusive transfer of the hydride ligand to the 2‐position is observed and also at higher temperatures no 1,2→1,4 isomerization is found. The heteroleptic product DIPPnacnac‐Ca(1,2‐dihydropyridide)?(pyridine) shows fast ligand exchange into homoleptic calcium complexes and therefore could not be isolated. Calcium hydride reduction of isoquinoline gave well‐defined homoleptic products which could be characterized by X‐ray diffraction: Ca(1,2‐dihydroisoquinolide)₂?(isoquinoline)₄ and Ca₃(1,2‐dihydroisoquinolide)₆?(isoquinoline)₆. The striking selectivity difference in the dearomatization of pyridines by Mg or Ca complexes could be explained by DFT theory and was utilized in catalysis. Whereas hydroboration of pyridine with pinacol borane with a calcium hydride catalyst gave only minor conversion, the hydrosilylation of pyridine and quinolines with PhSiH₃ yields exclusively 1,2‐dihydropyridine and 1,2‐dihydroquinoline silanes with 80–90 % conversion. Similar results can be achieved with the catalyst Ca[N(SiMe₃)₂]₂?(THF)₂. These calcium complexes represent the first catalysts for the 1,2‐selective hydrosilylation of pyridines.     

Using the 1,2‐dihydro‐1,2‐diphosphinine ring as a template for the synthesis of new bicyclic structures and new trans‐chelating bis‐phosphines

The 1,2‐dihydro‐1,2‐diphosphinine decacarbonylditungsten complex 1 has been used as a synthetic equivalent of the corresponding 1,2‐dianion 2 . These two 1,2‐positions can be linked by a (CH₂)₄ bridge to yield a [4.4.0] bicyclic structure 6 whose identity has been confirmed by X‐ray crystal structure analysis. Alternatively, two ω‐iodohexyl chains can be grafted onto these positions and the resulting diiodo derivative 9 transformed into a long‐chain bis‐phosphine 10 by reaction with lithium diphenylphosphide. This bis‐phosphine gives a chelate complex with PdCl₂ whose trans‐stereochemistry was established by X‐ray crystal structure analysis. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:44–48, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20073     

C1‐Symmetric Bicyclo[2.2.2]octa‐2,5‐diene (bod*) Ligands in Rhodium‐Catalyzed Asymmetric 1,4‐Addition of Arylboronic Acids to Enones and 1,2‐Addition to N‐[(4‐Nitrophenyl)sulfonyl]imines

A set of ten C₁‐symmetric chiral bicyclo[2.2.2]octa‐2,5‐dienes (bod*) 2 (Fig. 1) were tested as ligands in Rh‐catalyzed arylation reactions. The 1,4‐addition of arylboronic acids to cyclohex‐2‐en‐1‐one, cyclopent‐2‐en‐1‐one, and tert‐butyl cinnamate proceeded smoothly with excellent enantioselectivities (up to 99% ee; Tables 1–3). The challenging 1,2‐addition of triphenylboroxine to N‐[(4‐nitrophenyl)sulfonyl]imines yielded the product in high yield and in good enantioselectivity (up to 92% ee; Table 4). Generally, the use of C₁‐symmetric chiral bod* ligands bearing bulky substituents resulted in lower enantioselectivities, whereas several electron‐poor and electron‐rich bod* ligands gave higher enantioselectivities than the benchmark ligands reported in literature.     

An Imidazoline–Aminophenol (IAP) Nickel Catalyst: Structure and Catalytic Activity in the Enantioselective 1,4‐Addition of 3′‐Indolyl‐3‐Oxindoles to Nitroethylene

The structure of a nickel complex of imidazoline–aminophenol (IAP) prepared from IAP with Ni(OAc)₂ was elucidated as cis‐bis(imidazolineaminophenoxide) [Ni(IAP)₂]. The [Ni(IAP)₂] complex smoothly promoted catalytic asymmetric 1,4‐addition of 3′‐indolyl‐3‐oxindole to nitroethylene to provide chiral mixed 3,3′‐bisindoles with high enantioselectivities. Mechanistic studies using ESI‐MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)₂] to generate the Ni–enolate of 3′‐indolyl‐3‐oxindole. From the optically active 3,3′‐mixed indole adduct, biologically important 3′‐indolyl‐3‐pyrrolidinoindoline was successfully synthesized in a three‐step reaction sequence.     

Room‐temperature Suzuki–Miyaura cross‐coupling reaction with α‐diimine Pd(II) catalysts

An α‐diimine Pd(II) complex containing chiral sec‐phenethyl groups, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dichloropalladium (rac‐ C1 ), was synthesized and characterized. rac‐ C1 was applied as an efficient catalyst for the Suzuki–Miyaura cross‐coupling reaction between various aniline halides and arylboronic acid in PEG‐400–H₂O at room temperature. Among a series of aniline halides, rac‐ C1 did not catalyze the cross‐coupling of aniline chlorides and fluorides but efficiently catalyzed the cross‐coupling of aniline bromides and iodides with phenylboronic acid. The catalytic activity reduced slightly with increasing steric hindrance of the aniline bromides. The complexes {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]‐2,3‐butadiene}dichloropalladium and {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]acenaphthene}dichloropalladium were also found to be efficient catalysts for the reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

Regiodirected Synthesis and Stereochemistry of 2,4,8‐Trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes and α,ω‐Bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes

2,4,8‐Trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes have been obtained by the regioselective and stereoselective cyclocondensation of 1,2‐ethanediamine with aldehydes RCHO (R═Me, Et, Prⁿ, Buⁿ, Pentⁿ) and H₂S at molar ratio 1:3:2 at 0°C. The increase in molar ratio of thiomethylation mixture RCHO–H₂S (6:4) at 40°C resulted in selective formation of bis‐(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)ethanes. Cyclothiomethylation of aliphatic α,ω‐diamines with aldehydes RCHO (R═Me, Et) and H₂S at molar ratio 1:6:4 and at 40°С led to α,ω‐bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes. Stereochemistry of 2,4,8‐trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes have been determined by means of ¹H and ¹³С NMR spectroscopy and further supported by DFT calculations at the B3LYP/6‐31G(d,p) level. The structure of α,ω‐bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes was confirmed by single‐crystal X‐ray diffraction study.     

Adducts of 1,1,1‐tris(4‐hydroxy­phenyl)­ethane with 1,2‐bis(4‐pyridyl)­ethane and 1,2‐bis(4‐pyridyl)­ethene: continuously interwoven structures in three dimensions

In the adduct 1,2‐bis(4‐pyridyl)­ethane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₂H₁₂N₂·2C₂₀H₁₈O₃, the bipyridyl component lies across an inversion centre in P. The tris‐phenol mol­ecules [systematic name: 4,4′,4′′‐(ethane‐1,1,1‐triyl)­triphenol] are linked by O—H?O hydrogen bonds to form sheets built from R(38) rings, and symmetry‐related pairs of sheets are linked by the bipyridyl mol­ecules via O—H?N hydrogen bonds to form open bilayers. Each bilayer is interwoven with two adjacent bilayers, forming a continuous three‐dimensional structure. In the adduct 1,2‐bis(4‐pyridyl)­ethene–1,1,1‐tris(4‐hydroxy­phenyl)­ethane–methanol (1/1/1), C₁₂H₁₀N₂·C₂₀H₁₈O₃·CH₄O, the mol­ecules are linked by O—H?O and O—H?N hydrogen bonds into three interwoven three‐dimensional frameworks, generated by single spiral chains along [010] and [001] and a triple‐helical spiral along [100].     

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

(Z)‐1,2‐Diaryl‐1,2‐bis(pinacolatoboryl)ethenes underwent double‐cross‐coupling reactions with 1‐bromo‐2‐[(Z)‐2‐bromoethenyl]arenes in the presence of [Pd(PPh₃)₄] as a catalyst and 3 M aqueous Cs₂CO₃ as a base in THF at 80 °C. The double‐coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2‐bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd₂(dba)₃] (dba=dibenzylideneacetone) and 2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)‐2‐bromoethenyl]benzenes as diboryl coupling partners.     

Synthesis of New C2‐Symmetric Chiral Bisamides from (1S,2S)‐Cyclohexane‐1,2‐dicarboxylic Acid

A series of new C₂‐symmetric (1S,2S)‐cyclohexane‐1,2‐dicarboxamides was synthesized from (1S,2S)‐cyclohexane‐1,2‐dicarbonyl dichloride and N‐benzyl‐substituted aromatic amines, which were prepared from 2‐aminopyridine, 2‐chloroaniline, and 2‐aminophenol via imine formation with benzaldehyde and subsequent reduction with NaBH₄. (1S,2S)‐N,N′‐Dibenzyl‐N,N′‐bis[2‐(benzyloxy)phenyl]cyclohexane‐1,2‐dicarboxamide was converted to (1S,2S)‐N,N′‐dibenzyl‐N,N′‐bis(2‐hydroxyphenyl)cyclohexane‐1,2‐dicarboxamide via hydrogenolysis in the presence of Pd(OH)₂ on active carbon powder.     

Reaktion von Bis(methylzink)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethan mit Triisopropylsilylphosphan und ‐arsan

Reaction of Bis(methylzinc)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane with Triisopropylsilylphosphane and ‐arsane The reaction of bis(methylzinc)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane ( 1 ) with triisopropylsilylphosphane gives the three‐nuclear complex [1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane]trizinc‐bis(μ‐triisopropylsilylphosphanediide) ( 2 ). Two zinc atoms show the coordination number of four whereas the third metal center is located between the two phosphorus atoms with a bent P–Zn–P‐moiety. The reaction of 1 with triisopropylsilylarsane proceeds analoguesly, however, we were not able to isolate analytically pure [1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane]trizinc‐bis(μ‐triisopropylsilylarsanediide) ( 3 ).     

(1R,2R)‐1,2‐Di­phenyl‐1,2‐bis(8‐quinoline­sulfonyl­amino)ethyl­enedi­amine–acetone (1/1)

The crystal structure of the new chiral complex (1R,2R)‐1,2‐di­phenyl‐1,2‐bis(8‐quinoline­sulfonyl­amino)‐ ethyl­enedi­amine–acetone (1/1), C₃₂H₂₆N₄O₄S₂^.C₃H₆O, is reported. The conformation of the C₃₂H₂₆N₄O₄S₂ (BQSDA) mol­ecule is determined by a bifurcated N—H?N hydrogen‐bond system. The acetone of solvation is linked to the BQSDA mol­ecule by an N—H?O hydrogen bond.     

Bismuth triflate–L(−)‐proline catalyzed synthesis of chiral 2,5‐diaryl‐2,3‐dihydropyrano[2,3‐b]quinolin‐4‐ones

The synthesis of chiral (2R) 2,5‐diaryl‐2,3‐dihydropyrano[2,3‐b]quinolin‐4‐ones, was achieved, at ambient temperature, by the reaction of 3‐acetyl‐4‐aryl‐carbostyril and an aldehyde, in the presence of bismuth triflate–L(?)‐proline complex, formed in situ. The products were obtained in 62–78% yield with high enantioselectivity (72–96% ee). J. Heterocyclic Chem., (2011).     

Synthesis,characterization, X‐ray crystal structure and in vitro antitumour activity of sodium bis(2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylato)triphenylstannate

Sodium bis[2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylato]triphenylstannate, [(CH₃OCH₂CH₂OCH₂CH₂OCH₂CH₂)‐1,2‐C₂B₁₀H₁₀‐9‐COO)₂SnPh₃]^? Na⁺, compound 1, was synthesized by the 1:1 condensation of triphenyltin(IV) hydroxide with 2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylic acid and crystallized in the presence of sodium bicarbonate. Its structure was determined by spectroscopy, elemental analysis and X‐ray diffraction. The structure of 1 consists of trigonal bipyramidal [Sn(Ph)₃(L)₂]^? anions and Na⁺ cations coordinated by oxygen atoms of polyoxaalkyl chains of different stannate anions, forming cation–anion chains elongated along the c axis. Compound 1 is significantly more active in vitro against seven tumour cell lines of human origin than 5‐fluorouracil, cis‐platin, carboplatin, and previously reported organotin carboranecarboxylates, but is less active than organotin polyoxaalkylcarboxylates. Copyright © 2004 John Wiley & Sons, Ltd.     

New chiral α‐diimine nickel(II) complexes bearing ortho‐sec‐phenethyl groups for ethylene polymerization

A series of new α‐diimine nickel(II) catalysts bearing bulky chiral sec‐phenethyl groups have been synthesized and characterized. The molecular structure of representative chiral ligand, bis[N,N′‐(4‐methyl‐2,6‐di‐sec‐phenethylphenyl)imino]‐1,2‐dimethylethane rac‐1c and chiral complexes, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dibromidonickel rac‐2a and bis{bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dibromidonickel rac‐2b, were confirmed by X‐ray crystallographic analysis. Complex rac‐2c bearing two chiral sec‐phenethyl groups in the ortho‐aryl position and a methyl group in the para‐aryl position, activated by diethylaluminum chloride (DEAC), showed highly catalytic activity for the polymerization of ethylene [4.12 × 10⁶ g PE (mol Ni.h.bar)^?1], and produced highly branched polyethylenes under low ethylene pressure (branching degree: 104, 118 and 126 branches/1000 C at 20, 40 and 60°C, respectively). Chiral 20‐electron bis‐α‐diimine Ni(II) complex rac‐2b also exhibited high activity toward ethylene polymerization [1.71 × 10⁶ g PE (mol Ni · h · bar)^?1]. The type and amount of branches of the polyethylenes obtained were determined by ¹H and ¹³C NMR. Copyright © 2013 John Wiley & Sons, Ltd.     

Recyclable 1,2‐bis[3,5‐bis(trifluoromethyl)phenyl]diselane‐catalyzed oxidation of cyclohexene with H2O2: a practical access to trans‐1,2‐cyclohexanediol

1,2‐Bis[3,5‐bis(trifluoromethyl)phenyl]diselane‐catalyzed oxidation of cyclohexene by hydrogen peroxide affords a quick, clean and practical access to the important compound trans‐1,2‐cyclohexanediol under mild conditions. The highly atom‐economic properties, clean procedures, high reaction concentration, short reaction time, mild conditions and eco‐friendly, recyclable and low loading catalysts facilitate this methodology for possible future practical industrial production. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel two‐dimensional MnII coordination polymer with 1,2‐bis­(imidazol‐1‐yl)­ethane

In the crystal structure of the title complex, poly­[[di­azido­manganese(II)]‐di‐μ‐1,2‐bis­(imidazol‐1‐yl)­ethane‐κ⁴N³:N^3′], [Mn(N₃)₂(C₈H₁₀N₄)₂]_n or [Mn(N₃)₂(bim)₂]_n, where bim is 1,2‐­bis(imidazol‐1‐yl)­ethane, each Mn^II atom is six‐coordinated in a distorted octahedral coordination environment to four N atoms from four bim ligands and two N atoms from two azide ligands. The Mn^II atoms, which lie on inversion centres, are bridged by four bim ligands to form a two‐dimensional (4,4)‐network. The azide ligands are monodentate (terminal).     

A three‐dimensional heterometallic CuI/VIV 1,2‐bis(1,2,4‐triazol‐4‐yl)ethane framework: a new insight into the structure of vanadium oxyfluoride coordination hybrids

The bitopic ligand 1,2‐bis(1,2,4‐triazol‐4‐yl)ethane (tr₂eth) provides an unprecedented short‐distance N¹:N²‐triazole bridging of Cu^I and V^IV ions in poly[bis[μ₄‐1,2‐bis(1,2,4‐triazol‐4‐yl)ethane]di‐μ₂‐fluorido‐tetrafluoridodi‐μ₂‐oxido‐dicopper(I)divanadium(IV)], [Cu₂V₂F₆O₂(C₆H₈N₆)₂]_n. The Cu^I ions and tr₂eth linkers afford a two‐dimensional square‐grid topology involving centrosymmetric (tr)Cu(μ‐tr)₂Cu(tr) [tr is triazole; Cu—N = 1.9525 (16)–2.0768 (18) Å] binuclear net nodes, which are expanded in a third dimension by centrosymmetric [V₂O₂F₆]²⁻ pillars. The concerted μ‐tr and μ‐O bridging between the Cu^I and V^IV ions allows a multi‐centre accommodation of the vanadium oxyfluoride moiety on a cationic Cu/tr₂eth matrix [Cu—O = 2.1979 (15) Å and V—N = 2.1929 (17) Å]. The distorted octahedral coordination of [VONF₄] is completed by two terminal and two bridging F⁻ ions [V—F = 1.8874 (14)–1.8928 (13) and 2.0017 (13)–2.1192 (12) Å, respectively]. The resulting three‐dimensional framework has a primitive cubic net topology and adopts a threefold interpenetration.     

Kristallstrukturen und spektroskopische Eigenschaften von 2λ3‐Phospha‐1, 3‐dionaten und 1, 3‐Dionaten des Calciums ‐ ein Vergleich am Beispiel der 1, 3‐Diphenyl‐ und 1, 3‐Di(tert‐butyl)‐Derivate

Crystal Structures and Spectroscopic Properties of 2λ³‐Phospha‐1, 3‐dionates and 1, 3‐Dionates of Calcium ‐ Comparative Studies on the 1, 3‐Diphenyl and 1, 3‐Di(tert‐butyl) Derivatives A hydrogen‐metal exchange between dibenzoylphosphane and calcium carbide in tetrahydrofuran (THF) followed by addition of the ligand 1, 3, 5‐trimethyl‐1, 3, 5‐triazinane (TMTA) furnishes the binuclear complex bis[(tmta‐N, N′, N″)calcium bis(dibenzoylphosphanide)] ( 1a ) co‐crystallizing with benzene. Similarly, reaction of bis(2, 2‐dimethylpropionyl)phosphane with bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in 1, 2‐dimethoxyethane (DME) gives bis(dme‐O, O′)calcium bis[bis(2, 2‐dimethylpropionyl)phosphanide] ( 1b ) in high yield. The carbon analogues 1, 3‐diphenylpropane‐1, 3‐dione (dibenzoylmethane) or 2, 2, 6, 6‐tetramethylheptane‐3, 5‐dione (dipivaloylmethane) and bis(thf‐O)calcium bis[tris(trimethylsilylmethyl)zincate] in DME afford bis(dme‐O, O′)calcium bis(dibenzoylmethanide) ( 2a ) and the binuclear complex (μ‐dme‐O, O′)bis[(dme‐O, O′)calcium bis(dipivaloylmethanide)] ( 2b ), respectively. Dialkylzinc formed during the metalation reaction shows no reactivity towards the 1, 3‐dionates 2a and 2b . Finally, from the reaction of the unsymmetrically substituted ligand 2‐(methoxycarbonyl)cyclopentanone and bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in toluene, the trinuclear complex 3 is obtained, co‐crystallizing with THF. The β‐ketoester anion bridges solely via the cyclopentanone unit.     

Synthesis and photovoltaic properties of 2,6‐bis(2‐thienyl) benzobisazole and 4,8‐bis(thienyl)‐benzo[1,2‐B:4,5‐B′]dithiophene copolymers

In an effort to design efficient low‐cost polymers for use in organic photovoltaic cells the easily prepared donor–acceptor–donor triad of a either cis‐benzobisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole flanked by two thiophene rings was combined with the electron‐rich 4,8‐bis(5‐(2‐ethylhexyl)‐thien‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene. The electrochemical, optical, morphological, charge transport, and photovoltaic properties of the resulting terpolymers were investigated. Although the polymers differed in the arrangement and/or nature of the chalcogens, they all had similar highest occupied molecular orbital energy levels (?5.2 to ?5.3 eV) and optical band gaps (2.1–2.2 eV). However, the lowest unoccupied molecular orbital energy levels ranged from ?3.1 to ?3.5 eV. When the polymers were used as electron donors in bulk heterojunction photovoltaic devices with PC₇₁BM ([6,6]‐phenyl C₇₁‐butyric acid methyl ester) as the acceptor, the trans‐benzobisoxazole polymer had the best performance with a power conversion efficiency of 2.8%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 316–324     

Crystal structure and photoreactivity of a halogen‐bonded cocrystal based upon 1,2‐diiodoperchlorobenzene and 1,2‐bis(pyridin‐4‐yl)ethylene

The formation of a photoreactive cocrystal based upon 1,2‐diiodoperchlorobenzene ( 1,2‐C₆I₂Cl₄ ) and trans‐1,2‐bis(pyridin‐4‐yl)ethylene ( BPE ) has been achieved. The resulting cocrystal, 2( 1,2‐C₆I₂Cl₄ )·( BPE ) or C₆Cl₄I₂·0.5C₁₂H₁₀N₂, comprises planar sheets of the components held together by the combination of I…N halogen bonds and halogen–halogen contacts. Notably, the 1,2‐C₆I₂Cl₄ molecules π‐stack in a homogeneous and face‐to‐face orientation that results in an infinite column of the halogen‐bond donor. As a consequence of this stacking arrangement and I…N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid‐state [2 + 2] cycloaddition reaction that produces rctt‐tetrakis(pyridin‐4‐yl)cyclobutane ( TPCB ) with an overall yield of 89%. A solvent‐free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield.