Reaction of 5,5-diphenyl-2-thiohydantoin with 1,3-dibromopropane under phase transfer catalytic conditions : Crystal and molecular structure of 2,3,4,5-tetrahydro-7,7-diphenylimidazo-[2,1-b]-thiazine -6(7H)-one

The reaction of the potassium salt of 5,5-diphenyl-2-thiohydantoin with 1,3-dibromopropane and triethylamine carried out under phase transfer catalytic conditions gave almost quantitatively two isomeric diphenylimidazothiazine 2 and 3 in a ratio ca 1:2. 2,3,4,5-Tetrahydro-7,7-diphenylimidazo- [2,1-b]-thiazine-6(7H)-one (3) crystallises from DMSO in the space group P2₁2₁2₁ with a = 8.488(3), b = 11.682(4), c = 15.522(5)Å. The 6-membered thiazine ring in 3 adopts a sofa conformation.     

Azetidines and 1-pyrrolines from an electron-deficient allene and C  N compounds

The (2+2) cycloadditions of 1,3-di-t-butylallene-1,3-dicarbonitrile (3) to azomethines or an acyclic amidine afford 2-alkylidene azetidines 12, 19. In the reaction of 3 with the 3-dimethylamino-2H-azirine 20 the 1,2 bond of the 3-membered ring is cleaved to give the stereoisomeric 1-pyrrolines 23.     

Regio- and stereoselective reactions of a rhodanine derivative with optically active 2-methyl- and 2-phenyloxirane

The reaction of a rhodanine derivative (=(Z)-5-benzylidene-3-phenyl-2-thioxo-1,3-thiazolidin-4-one; 1) with (S)-2-methyloxirane (2) in the presence of SiO₂ in dry CH₂Cl₂ for 10 days led to two diastereoisomeric spirocyclic 1,3-oxathiolanes 3 and 4 with the Me group at C(2) (Scheme 2). The analogous reaction of 1 with (R)-2-phenyloxirane (5) afforded also two diastereoisomeric spirocyclic 1,3-oxathiolanes 6 and 7 bearing the Ph group at C(3) (Scheme 3). The structures of 3, 4, 6, and 7 were confirmed by X-ray crystallography (Figs. 1 and 2). These results show that oxiranes react selectively with the thiocarbonyl group (CS) in 1. Furthermore, the nucleophilic attack of the thiocarbonyl S-atom at the SiO₂-activated oxirane ring proceeds with high regio- and stereoselectivity via an S_N2-type mechanism.     

REACTION OF 5,5-DIPHENYL-2-THIOHYDANTOIN WITH 1,4-DIBROMOBUTANE. THE CRYSTAL AND MOLECULAR STRUCTURE OF 2,3,4,5-TETRAHYDRO-7,7-DIPHENYLIMIDAZO-[2,1-b]-THIAZEPINE-8(7H)-ONE

Abstract

The reaction of 5,5-diphenyl-2-thiohydantoin (1) (DPTH) or its potassium salt (DPTH-K) with 1,4-dibromobutane gave two isomeric bicyclic products: 2,3,4,5-tetrahydro-7,7-diphenylimidazo-[2,1-b]-thiazepine-8(7H)-one (6) and 2,3,4,5-tetrahydro-8,8-diphenylimidazo-[2,1-b]-thiazepine-7(8)-one (7) in different ratios depending on the reaction conditions: [DPTH-K, EtOH, N-ethylpiperdine; phase transfer catalytical conditions: DPTH-K, Et₃N, benzene/water or DPTH acetone/K₂CO₃]. Compound (6) crystallizes in the space group P2₁/c with a = 10.4624(2), b = 8.3643(1), c = 18.4371(3) Å β = 96.3(1)°. The 7-membered thiazepine ring in (6) adopts a disordered chain conformation. The discussion of some physico-chemical properties and some factors showing the influence on the yield and ratios of isomeric compounds [(2), (3)], [(4), (5)] and [(6), (7)], obtained in the alkylation of DTPH (1) with dibromoalkanes, has been carried out.     

Formation of 3-[amino(aryl)-methylidene]-1,3-dihydro-2H-indol-2-ones involving ring transformation of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles

The reaction of 3-bromooxindole with substituted (hetero)aromatic thioamides in acetonitrile was studied. At room temperature the reaction preferably gives products of ring transformation i.e. 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles (3b-f,h) whereas at elevated temperature products of an Eschenmoser coupling reaction, i.e. 3-[amino(aryl)-methylidene]-1,3-dihydro-2H-indol-2-ones (2b-f), are formed exclusively. There exist only two exceptions (4-methoxy and 2-pyridinthioamide) in which the Eschenmoser coupling reaction always takes place giving 2a and 2g. Also N-methylation of the starting 3-bromooxindole completely prevents formation of thiazoles. The prepared thiazoles 3b-f are unstable in solution and they undergo slow ring transformation to 2b-f. The rate limiting step of this rearrangement involves cleavage of an intermediary thiirane ring, which is slowed down by electron-withdrawing substituents on the thioamide (ρ = ?1.15).     

(Fluorosilyl)ethylenediamines and fluorosilyl-1,3-diaza-2-silacyclopentanes

This paper presents the chemistry of ethylenediamines and fluorosilanes. The synthesis of thermally stable monosilyl (1-5)- and bis(fluorosilyl)ethylenediamines (6) is described. Starting with the dilithium salt of ethylenediamine and F₂Si(CMe₃)₂ the five-membered 1,3-diaza-2-silacyclopentane (8) is obtained. The reaction of tetra- and trifluorosilanes with dilithiated bis(silyl)ethylenediamines leads to the formation of 1,3-diaza-2-fluorosilylsilacyclopentanes (9-14). Fluorosilanes substitute 8 in 1 and 3 positions (15-28). A fluorosilyl-bridged five-membered ring (29) is isolated in the reaction of 1-trimethylsilyl-1,3-diaza-2-silacyclopentane, BuLi and MeSiF₃. In the synthesis of N-fluorosilyl-1,3-diaza-2-silacyclopentanes constitutional isomers were formed (30-33). Quantum-chemical calculations support the isomerisation mechanism. An iminosilane with an SiN double bond is the intermediate product of the rearrangement process.Crystal structures of 7, 13, 20 and 23 are reported.     

A novel synthesis of 2'-hydroxy-1',3'-xylyl crown ethers

Six novel 2' - hydroxy - 1',3' - xylyl crown ethers (8a–e and 13)¹ have been synthesized utilizing the allyl group to protect the OH function during the cyclization reaction. The macrocycles 6a-e were formed in yields of 26 to 52%, by intermolecular reaction of 4 - chloro - 2,6 - bis(bromomethyl) - 1 - (2 - propenyloxy)benzene (5) with polyethylene glycols; 6a was also obtained by an intramolecular cyclization reaction of monotosylate 14.A 30-membered ring with a 2' - hydroxy - 1',3' - xylyl sub-unit was obtained in 87% yield by reaction of ditosylate 9 with bis [2 - (o - hydroxyphenoxy)ethyl]ether (11) in the presence of cesium fluoride. The synthesis of crown ethers with a 2' - hydroxy - 1',3' - xylyl sub-unit (1c–e, H for CH₃) by demethylation of the corresponding 2'-methoxy crown ethers 1c–e with lithium iodide were unsuccessful; it would appear that the demethylation reaction is restricted to 15- and 18-membered rings. One of the 2' - hydroxy - 1',3' - xylyl crown ethers 8d forms a crystalline 1:1-complex with water.     

Cyclic Polysilanes : XIII. Ring closure reactions of α,ω-dichloropermethylpolysilanes; The preparation of heterocyclic phenylphosphapermethylsilanes (PhP)m(SiMe2)n

The reactions of the dichloropermethylsilanes Cl(SiMe₂)_nCl (n = 1?6) with dilithium phenylphosphide yield a series of novel heterocyclic phosphasilanes. For n = 4, 5 and 6, the reaction leads to the corresponding 5-, 6- and 7-membered cyclic monophosphapolysilanes PhP(SiMe₂)_n, but when n = 3, a polymeric material of probable formula [PhP(SiMe₂)₃]_n is formed. For n = 2, ring closure again occurs, to yield the 6-membered P₂Si₄ ring compound [PhP(SiMe₂)₂]₂. With dimethyldichlorosilane, cyclization results in the dimeric phosphasilane (PhPSiMe₂)₂ at ?40°C, and the corresponding trimeric derivative (PhPSiMe₂)₃ at +40°C. These two ring sizes exist in an equilibrium (PhPSiMe₂)₂ ? (PhPSiMe₂)₃, the dimer being stable at room temperature, but being converted into the trimer above 150°C. The ¹H, ¹³C, ²⁹Si and ³¹P NMR parameters are reported for all the compounds, and the chemical shifts and coupling constants interpreted in terms of the molecular and electronic structures of the different ring sizes.     

Mechanism of thermolysis of 2-hydrazono-Δ3-1,3,4-oxadiazolines to diazetidinium hydroxide inner salts : Evidence for an N-isocyanatoimine intermediate and its novel reaction with phenylisocyanate

Thermolysis of 5,5-dimethyl-2-diphenylmethylenehydrazone-Δ³-1,3,4-oxadiazoline (1a) in chlorobenzene at 130° leads to 1-diphenylmethyleneimino-4,4-dimethyl-3-oxo-1,2-diazetidinium hydroxide, inner salts (2). Evidence for initial fragmentation of 1a to 2-diazopropane (4) and N-isocyanatodiphenylmethylene imine (3), which subsequently recombine with loss of N₂ to form 2, includes trapping of both intermediates with phenylisocyanate and trapping of 3 with methanol. Intermediate 3, which is the first N-isocyanatoimine intermediate to be reported, undergoes a novel 1,3-cycloaddition reaction with phenylisocyanate.Examples of similar chemistry involving reactions of analogs of 1a in the presence of arylisocyanates are also included.     

Crystal structures of 2-ferrocenylmethylidenehydrazono-1,3-dithiane and 2-ferrocenylmethylidenehydrazono-1,3-dithiepane

Two compounds of 2-ferrocenylmethylidenehydrazono-1,3-dithiane (1) and 2-ferrocenylmethylidenehydrazono-1,3-dithiepane (2) are synthesized and their single crystal structures are determined by the X-ray diffraction method. Compound 1 belongs to the orthorhombic Pca2₁ space group with the cell parameters: a = 13.989(4) Å, b = 5.785(2) Å, c = 18.231(5) Å, V = 1475.4(7) ų; while compound 2 crystallizes in a monoclinic symmetry, P2₁/c space group with a = 15.320(2) Å, b = 5.8028(6) Å, c = 36.584(4) Å, β = 91.932(1)° and V = 3250.4(6) ų.     

Spectroscopic,anti-bacterial,anti-cancer and molecular docking of Pd(II) and Pt(II) complexes with (E)-4-((dimethylamino)methyl)-2-((4,5-dimethylthiazol-2-yl)diazenyl)phenol ligand

New ligand (E)-4-((dimethylamino)methyl)-2-((4,5-dimethylthiazol-2-yl)diazenyl)phenol (HDmazo) was prepared by the coupling reaction between 4,5-dimethylthiazol-2-amine and 4-((dimethylamino)methyl)phenol. Moreover, the [MCl₂(HDmazo)] and [M(HDmazo)₂] [M^II = Pd and Pt] were prepared using the direct reaction of equivalent molar of HDmazo and Na₂PdCl₄ or K₂PtCl₄. The HDmazo and its complexes were investigated by different spectroscopic techniques. In complexes (1–2) HDmazo ligand behaves as bidentate style through the nitrogen of azo group and nitrogen of thiazole ring towards Pd(II) and Pt(II). Or in a bidentate fashion via the oxygen atom of the hydroxylate group and nitrogen atom of azo group as mono-anion in complexes (3–4). Further, the study of biological activity against four pathogenic bacteria showed that compound (3) exhibited good activity compared to other compounds. Additional the anti-tumor action against A2870 cell lines was screened, and the complexes (1) and (2) displayed good activity with 7.45 ± 0.98 µM and 13.23 ± 1.43 µM, respectively. The binding mechanism of the prepared compounds with EGFR tyrosine kinase, was investigated using molecular docking experiments.     

Reactions of [LiC(SiMe2H)3]·2THF: Sterically hindered tris(dimethylsilyl)methane derivatives and their hydrosilylation

Treatment of LiC(SiMe₂H)₃]·2THF (1) with alkeny1chlorosilanes produced sterically hindered alkenylsilanes (4–10) of structure H₂C=CH---(CH₂)_nSiRR′C(SiMe₂H)₃ (R=Me; R′=Me or Cl; n=0, 1, or 4). The Peterson reaction of 1 with carbonyl compounds gave sterically hindered olefins R(R′)C=C(SiMe₂H)₂. Pt or Rh catalyzed intramolecular hydrosilylation of H₂C=CHSiMe₂C(SiMe₂H)₃ (4) occurred to produce a new 1,3-disilacyclobutane derivative 15. Intermolecular hydrosilylation was favored for 5, 8, and 10, producing oligomeric products.     

Zoanthoxanthin,a natural 1,3,5,7-tetrazacyclopent-azulene from Parazoanthus axinellae

Zoanthoxanthin, the principal fluorescent pigment of the mediterranean zoanthid Parazoanthus axinellae, has been isolated in crystalline form and identified as 2-amino-3,4-dimethyl-6-dimethylamino-3H-1,3,5,7-tetrazacyclopen 1 from its chemical and spectral properties and by X-ray crystallographic analysis of its 2-chloro-derivative 3.Crystals of 3 are monoclinic, space group P2₁c, with Z = 4, in a unit cell of dimensions a = 7·282, b = 8·408, c = 25·422 A°, β = 94·31°. The structural analysis, carried out by direct methods and refined to an R value of 0·040, has shown that the molecule is nearly planar, the 7-membered carbocyclic ring assuming a shallow boat conformation while the two imidazole rings are slightly bent in the opposite direction with respect to the folding of the central ring.     

Studies in macrolide synthesis: A concise asymmetric synthesis of a macrolide intermediate for the erythronolides.

The enantiomerically-pure 14-membered ring macrolide 1 is prepared in 14 steps from the racemic aldehyde 4, Z=SPh. The C₂-C₄ and C₈-C₁₀ stereorelationships in 1 are controlled in a single step by an Evans aldol condensation with (±)-4. Macrolactonisation, 23 → 1, takes place in high yield (91%).     

Lipase mediated resolution of 1,3-butanediol derivatives: chiral building blocks for pheromone enantiosynthesis. Part 3

(R,S)-1,3-Butanediol 5 was kinetically resolved by enzymatic acetylation with vinyl acetate under the presence of Chirazyme™ L-2, c–f, yielding (S)-1-O-acetyl-1,3-hydroxybutane 6 and (R)-1,3-di-O-acetyl-1,3-butanediol 7 with enantiomeric excesses of 91% (E=67.3). Compounds 6 and 7 were easily transformed into the corresponding (S)-3-O-(2-methoxyethoxymethyl)-3-hydroxybutanal 10 and (R)-3-benzyloxybutanal 19, through a protection–deprotection and functional group interchange methodology. Subsequent reaction of 10 and 19 with 3-(methoxycarbonylpropionylmethylene)triphenylphosphorane afforded methyl (E,S)-8-O-(2-methoxyethoxymethyl)-4-oxo-5-nonenoate 12 and (E,R)-8-benzyloxy-4-oxo-5-nonenoate 20. The alkenes 19 and 20 were then catalytically hydrogenated to the corresponding saturated esters 13 and 21. Treatment of 13 and 21 with 1,2-ethanedithiol/F₃B·OEt₂ afforded dithioketals 14 and 22, which were respectively reduced to (S)-1,8-dihydroxy-4-nonanone ethylidenedithioketal 15 and (R)-8-O-benzyl-1,8-dihydroxy-4-nonanone ethylidenedithioketal 23. Finally, deprotection of 15 by catalytic hydrogenation under acidic conditions gave the expected (5S,7S)-(−)-7-methyl-1,6-dioxaspiro[4.5]decane 1. The (5R,7R)-(+)-1 enantiomer was analogously prepared from 23. Both compounds were formed by this procedure with an e.e. of 91%.     

Crystal structure and fluorescent properties of a 2D cadmium coordination polymer

A new 2D cadmium(II) coordination polymer {[Cd(MBD)(L)]·(H₂O)₂} _n (1) (H₂MBD = 5-methoxycarbonyl-benzene-1,3-dicarboxylic acid, L = 1,3-bis(benzimidazol-l-yl)-2-propanol) is synthesized, in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during the synthesis. In the structure of complex 1, each cadmium center is octahedrally coordinated by four O atoms from three carboxylate groups and two N of distinct L ligands. A detailed structural analysis reveales that compound 1 exhibits a unique 2D binodal (3,5)-connected (4².6⁷.8)(4².6) topology structure. Furthermore, the 2D layer is extended into a 3D network through π-π stacking interactions. The solid-state fluorescence properties of 1 are investigated at room temperature.     

Influence of CH3 substituents on tetrahydropyrimidin-2-ylidene: σ-donating properties and in situ catalytic activities of precursor salts/Pd(OAc)2 system for C-C coupling reactions

In this study, symmetrical and non-symmetrical 1,3-dialkyltetrahydropyrimidinium salts (1·HCl and 2·HBr, respectively), bearing two methyl groups at C₅ position of the pyrimidine ring were synthesized and characterized. One of the new salts 1,3-bis(2,4,6-trimethylbenzyl)-5,5-dimethyl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate (1a·HBF₄, 1a = 6-Bn∗-Me₂) was converted to cis-[RhCl(6-Bn∗-Me₂)(CO)₂] to determine the σ-donating properties in comparison to those of their 5-membered NHC complexes. Furthermore, the in situ catalytic activities of all salts, in combination with Pd(OAc)₂, were tested for the Heck-Mizoraki and Suzuki-Miyaura type C-C coupling reactions. In contrast to the expectation, only the substituents on N,N′-atoms were found to play an important role in the catalytic activity.     

Researches on alkoxysilanes

Reaction of 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-glycols, and of catechol, pentaerythritol, and glycerol with dialkyldichlorosilanes (in the presence of tertiary amines) dialkyldialkoxysilanes, or polydialkylsiloxanes gives 30 ethers of dialkylsilanediols containing 5, 6, 7, 8, 9, and 10-membered rings (16 being new). Among them are 8-membered ring ethers containing along with Si, O, and C, N or S, and 6-membered ring ethers containing NH₂, NO₂, and OH groups. 2-Sila -1,3-dioxolanes are obtained only when formation of the 1,3,6,8-tetraoxa-2, 7-disilacyclodecane ring is hindered or prevented by the presence of one or two substituents on each carbon atom with two substituents on the silicon. 2, 2-Dialkyl-1, 3-dioxa-2-silacyclanes, which contain 8 and 9-membered rings, can be obtained only by thermal depolymerization of originally formed polymeric ethers of the type [-O(CH₂)_nOSiR₂-]_m. Many of the monomeric cyclic ethers prepared dimerize or polymerize on keeping.For Part XVI see [1].     

Preparation and structural characterization of Os(II) and Ru(II) complexes,MCl2(vdpp)2 [M = Os or Ru,vdpp = 1,1-bis(diphenylphosphino)ethene]

A reaction between Os₂(O₂CCH₃)₄Cl₂ and vdpp [vdpp = 1,1-bis(diphenylphosphino) ethene] was investigated. When the reactants, in the presence of LiCl, were heated in toluene OsCl₂(vdpp)₂,1, was formed. In a similar reaction Ru₂(O₂CCH₃)₄Cl with vdpp afforded RuCl₂(vdpp)₂,2. The molecular structures of1 and2 were elucidated using X-ray crystallography. Single crystals of1 and2 grown from dichloromethanehexane crystallize in the space group P2₁/c with these cell dimensions: a = 11.046(2)Å, b = 18.168(3)Å, c = 12.678(3)Å, β = 110.24(2)° and V = 2387(2)ų for1 and a = 11.055(1)Å, b = 18.199(3)Å, c = 12.693(2)Å, β = 110.16(1)°, V = 2392(1)ų for2. The molecules of1 and2 are isostructural. Metal atoms reside on inversion centers relating the two halves of the molecules. The complexes are six-coordinate with two four-membered chelate rings and trans chlorine atoms. For RuCl₂(vdpp)₂ the PMP angle in the chelate ring is 73.13(2)° and the PCP angle in the chelate ring is 98.6(1)°. These values are 72.74(3)° and 97.9(2)°, respectively, for OsCl₂(vdpp)₂. There is a disordered dichloromethane solvent molecule present in the lattice and there are no unusual intermolecular contacts.     

A 3D Ba-MOF for selective adsorption of CO_2/CH_4 and CO_2/N_2

An unexpected in-situ hydrolysis reaction occurred during the solvothermal reaction of N,N'-bis(4-carboxy-2-methylphenyl)pyromellitic di-imide) and Ba(NO_3)_2,and a novel porous Ba-MOF,[H_2 N(CH_3)_2]_(0.5) [Ba_(1.5)(L)(DMA)]·1.5 DMA·1.5 H_2 O(UPC-70,H3 L=2-(4-ca rboxy-2-methylphenyl)-1,3-dioxoisoindoline-5,6-dicarboxylic acid,DMA=N,N-dimethylacetamide),was obtained on the basis of the partial hydrolysate.The as-synthesized 3 D network with 1 D open channels of different sizes(24 A and 10 A)contains abundant open metal sites after removal of solvents,which is conducive to the preferential adsorption of CO_2.The subsequent gas sorption measurement reveals the high separation selectivity of UPC-70 for CO_2/CH_4(15) and CO_2/N_2(32) at ambient conditions,and GCMC theoretical simulation provides good verification of the experimental results,indicating that UPC-70 is a potential candidate for CO_2 capture from flue gas and natural gas.