(3aS,7aS)‐1‐{2‐Oxo‐1,3‐bis­[(S)‐1‐phen­ylethyl]­per­hydro‐1,3,2λ5‐benzodi­aza­phosphol‐2‐yl}‐1‐phenylmethanol: a mixture of dia­stereoiso­mers in a disordered crystal

In the title compound, C₂₉H₃₅N₂O₂P, the stereogenic C center α to the P atom, formed during the Pudovik condensation reaction between a deprotonated chiral diaza­phosphole and benz­aldehyde, has disordered substituents, giving a mixture of Cα‐R and Cα‐S diastereoisomers. Moreover, this compound crystallizes with two independent mol­ecules in the asymmetric unit. The observed configuration at the Cα atom is 0.741 (6)‐S mixed with 0.259 (6)‐R, indicating diastereoisomeric enrichment during crystallization. Data from solution and solid‐state studies consistently point to an epimerization process at the Cα atom.     

(4S,5S)‐(+)‐4‐Hydro­xy­methyl‐2,5‐di­phenyl­oxazoline

The absolute configuration of the title compound, alter­natively called (+)‐(4,5‐di­hydro‐2,5‐di­phenyl­oxazol‐4‐yl)­methanol, C₁₆H₁₅NO₂, has been confirmed as 4S,5S. The hydroxy­methyl group and phenyl ring at the asymmetric C atoms exhibit β and α orientations, respectively. The exocyclic C—C bonds at the asymmetric C atoms are mutually anticlinal (?ac). The hydroxyl group and the N atom of the oxazoline ring are involved in an intermolecular hydrogen bond leading to chains of mol­ecules.     

A new optically pure half‐sandwich Cp–Ru diphosphine complex with a chiral metal centre, (S)‐Ru(η5‐C5H5)(EPHOS)Cl {EPHOS is (+)‐(1R,2S)‐2‐[(diphenylphosphino)methylamino]‐1‐phenylpropyl diphenylphosphinite}

The crystal structure of the title compound, chloro(η⁵‐cyclopenta­dienyl){(1R,2S)‐2‐[(di­phenyl­phosphino)­methyl­amino]‐1‐phenyl­propyl di­phenyl­phosphinite‐κ²P,P′}ruthenium(II), [Ru(C₅H₅)Cl(C₃₄H₃₃NOP₂)], is reported. The pseudo‐octa­hedral complex is chiral and the configuration at the Ru atom is S. The seven‐membered metallacycle adopts a boat‐like conformation.     

Absolute configuration of (+)‐(S)‐2‐(5‐fluoro‐2‐methoxy‐1,4‐benzodioxan‐2‐yl)­imidazolinium bromide

The title compound, C₁₂H₁₄FN₂O₃⁺·Br^?, crystallizes in the non‐centrosymmetric P2₁2₁2₁ space group. The absolute configuration of the pharmacologically active mol­ecule could be resolved in the hydro­bromide salt, the structure of which is reported. The mol­ecule of the title compound has the S configuration. The molecular packing in the crystal is stabilized by weak N—H?Br [N?Br = 3.240 (4) and 3.302 (4) Å] hydrogen bonding.     

rac‐(Z)‐Ethyl 2‐bromo‐2‐[(3R,5R)‐3‐bromo‐5‐methyl­tetra­hydro­furan‐2‐yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan‐2‐yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry‐equivalent mol­ecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers.     

Resolution of (S,S)‐4‐(2,2,4‐tri­methyl­chroman‐4‐yl)­phenyl camphanate and its 4‐chromanyl epimer by crystallization

Dianin's compound (4‐p‐hydroxy­phenyl‐2,2,4‐tri­methyl­chroman) has been resolved by crystallization of the (S)‐(−)‐camphanic esters (S,S)‐ and (R,S)‐4‐(2,2,4‐tri­methyl­chroman‐4‐yl)­phenyl 4,7,7‐tri­methyl‐3‐oxo‐2‐oxabi­cyclo[2.2.1]heptane‐1‐carboxyl­ate, both C₂₈H₃₂O₅, from 2‐methoxy­ethanol, yielding the pure S,S diastereomer. The relative stereochemistry of both diastereomers has been determined by X‐ray crystallography, from which the absolute stereochemistry could be deduced from the known configuration of the camphanate moiety. The crystallographic conformations have been analysed, including the 1:1 disorder of the R,S diastereomer.     

5‐(2‐Pyridyl)‐1,3‐di­thia­ne‐2‐thione

The title compound, C₉H₉NS₃, crystallizes with two mol­ecules in the asymmetric unit. In both mol­ecules, the di­thia­ne‐2‐thione rings adopt a symmetric half‐boat conformation with the C atom opposite the C—S_thione bond out of the plane. The pyridine ring is in an equatorial position and is twisted out of the plane of the half‐boat by 82.7 (2) and 84.5 (2)° in the two mol­ecules, so that the N atom is trans to the axial C—H bond in both cases.     

Two diastereomers of 9‐(2,6‐di­chloro­phenyl)‐4a‐hydroxy‐3,3,6,6‐tetra­methyl‐1,2,3,4,4a,5,6,7,8,9a‐deca­hydro­xanthene‐1,8‐dione in the same crystal

The reaction of dimedone with 2,6‐di­chloro­benz­aldehyde leads to the title compound, C₂₃H₂₆Cl₂O₄. In principle, the reaction could yield eight different stereoisomers. We have found four of them in the same crystal as two enantiomeric pairs of diastereomers, which means that the asymmetric unit is built up of two different diastereomers. Two of the three chiral centres display the same configuration, while the third is different in the two mol­ecules in the asymmetric unit. The packing of the mol­ecules is stabilized by hydrogen bonds between the hydroxy group and the carbonyl group attached to the cyclo­hexene ring, forming chains in which the different diastereomers alternate.     

Uncovering stereochemical relations in a compound with a stereogenic N—O axis: methyl 2‐(4‐methyl‐2‐thio­xo‐2,3‐di­hydro­thia­zol‐3‐yl­oxy)­propanoate

The geometry of racemic methyl 2‐(4‐methyl‐2‐thio­xo‐2,3‐di­hydro­thia­zol‐3‐yl­oxy)­propanoate, C₈H₁₁NO₃S₂, (I), is characterized by a distorted heterocyclic five‐membered ring and an enantiomorphic N‐alkoxy substituent, which is inclined at an angle of −68.8° to the thia­zole­thione plane in (M)‐(I). The unit cell consists of a 1:1 ratio of R,P‐ and S,M‐configured mol­ecules of (I). The combination of a P configuration at the N—O axis and an R configuration at the asymmetric propanoate C_β atom on one side, and an S,M configuration on the other side, is considered to originate from steric interactions. The largest substituent at the asymmetric propanoate C_β atom, i.e. the methoxycarbonyl group, resides above the methyl substituent; the medium‐sized propanoate γ‐methyl substituent points in the opposite direction with respect to the N—O bond, whereas the H atom is located above the C=S double bond of the thiazolethione subunit.     

Sodium 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate dihydrate

The title compound, Na⁺·C₉H₇N₄O₅S⁻·2H₂O, presents a Z configuration around the imine C=N bond and an E configuration around the C(O)NH₂ group, stabilized by two intra­molecular hydrogen bonds. The packing is governed by ionic inter­actions between the Na⁺ cation and the surrounding O atoms. The ionic unit, Na⁺ and 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate, forms layers extending in the bc plane. The layers are connected by hydrogen bonds involving the water mol­ecules.     

The first bipodal thio­carbamic acid ester,O,O′‐diethyl N,N′‐(p‐phenylene­di­carbonyl)­bis(­thio­carbamate)

The title compound, C₁₄H₁₆N₂O₄S₂, is the first reported X‐ray crystallographic structure determination of a bipodal O‐alkyl N‐benzoyl­thio­carbamate. This compound crystallizes in a cis‐S,O orientation (Z,Z′ configuration), with the two S/O moieties anti relative to one another, as indicated by the twofold rotation axis located at the center of the benzene ring.     

N‐(2‐Carboxy­benzoyl)‐l‐leucine methyl ester

The title compound (with the systematic name 2‐{[(1S)‐1‐(methoxy­carbonyl)‐3‐methyl­butyl]amino­carbonyl}benzoic acid), C₁₅H₁₉NO₅, crystallizes in the monoclinic space group P2₁, with two independent mol­ecules per asymmetric unit. The most notable difference between the two mol­ecules is in the dihedral angles between the planes of the carboxyl group and the benzene ring, which are 3.5 (3) and 25.7 (1)°. This difference may account for the fact that two competing reactions are observed in aqueous solution, namely cyclization to form the imide N‐phthaloyl­leucine and hydrolysis of N‐(2‐carboxy­benzoyl)‐l ‐leucine methyl ester to phthalic acid and leucine.     

Methyl (±)‐1‐ethyl‐2‐hydroxy‐4‐(4‐methoxybenzoyl)‐5‐(4‐methoxyphenyl)‐3‐oxo‐2,3‐di­hydro‐1H‐pyrrole‐2‐acetate

The title compound, C₂₄H₂₅NO₇, is a racemic mixture of 2,3‐di­hydro‐1H‐pyrrol‐3‐ones. It crystallizes in the triclinic system, space group P1, with Z = 2. The asymmetric unit contains two enantiomorphic mol­ecules and the structure is stabilized by hydrogen‐bond contacts.     

(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.     

(Z)‐3‐(1‐Methyl‐1H‐indol‐3‐yl)‐2‐(thio­phen‐3‐yl)­acrylo­nitrile

The title compound, C₁₆H₁₂N₂S, has been synthesized by base‐catalyzed condensation of 1‐methyl­indole‐3‐carbox­aldehyde with thio­phene‐3‐aceto­nitrile. The product assumes an approx­imately planar Z configuration. The mol­ecule has a thienyl‐ring flip disorder.     

The diastereoisomers methyl 5‐(S)‐[2‐(R)/(S)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate

The title diastereoisomers, methyl 5‐(S)‐[2‐(S)‐methoxy­carbonyl)‐2,3,4,5‐tetra­hydro­pyrrol‐1‐yl­carbonyl]‐1‐(4‐methyl­phenyl)‐4,5‐di­hydro­pyrazole‐3‐carboxyl­ate and methyl 5‐(S)‐[2‐(R)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methyl­phenyl)‐4,5‐di­hydro­pyrazole‐3‐carboxylate, both C₁₉H₂₃N₃O₅, have been studied in two crystalline forms. The first form, methyl 5‐(S)‐[2‐(S)‐methoxy­carbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐di­hydro­pyrazole‐3‐carboxyl­ate–methyl 5‐(S)‐[2‐(R)‐methoxy­carbonyl)‐2,3,4,5‐tetra­hydro­pyrrol‐1‐yl­carbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate (1/1), 2(S),5(S)‐C₁₉H₂₃N₃O₅·2(R),5(S)‐C₁₉H₂₃N₃O₅, contains both S,S and S,R isomers, while the second, methyl 5‐(S)‐[2‐(S)‐methoxycarbonyl)‐2,3,4,5‐tetrahydro­pyrrol‐1‐ylcarbonyl]‐1‐(4‐methyl­phenyl)‐4,5‐di­hydro­pyrazole‐3‐carboxyl­ate, 2(S),5(S)‐C₁₉H₂₃N₃O₅, is the pure S,S isomer. The S,S isomers in the two structures show very similar geometries, the maximum difference being about 15° on one torsion angle. The differences between the S,S and S,R isomers, apart from those due to the inversion of one chiral centre, are more remarkable, and are partially due to a possible rotational disorder of the 2‐­(methoxycarbonyl)tetrahydropyrrole group.     

(4S)‐3‐[(2R,3S)‐3‐Hydr­oxy‐2‐methyl‐3‐phenyl­propion­yl]‐4‐isopropyl­oxazolidin‐2‐one

The mol­ecule of the title compound, C₁₆H₂₁NO₄, is chiral and has three asymmetric centres. The absolute configuration was not determined via diffraction measurements on the crystal, but was established from the known absolute configuration of the starting material. In the crystal structure, the mol­ecules assemble through inter­molecular hydrogen bonds into a macrostructure with helical channels.     

(E)‐2‐[2‐(1‐Naphthyl)­vinyl]‐3‐tosyl‐2,3‐di­hydro‐1,3‐benzo­thia­zole

The title compound, C₂₆H₂₁NO₂S₂, which consists of a benzo­thia­zole skeleton with α‐naphthyl­vinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium–copper‐catalyzed heteroannulation. The E configuration of the mol­ecule about the vinyl C=C bond is established by the benzothiazole–naphthyl C—C—C—C torsion angle of 177.5 (4)°. The five‐membered heterocyclic ring adopts an envelope conformation with the Csp³ atom 0.380 (6) Å from the C₂NS plane. The two S—C [1.751 (4) and 1.838 (4) Å] and two N—C [1.426 (5) and 1.482 (5) Å] bond lengths in the thia­zole ring differ significantly.     

cis‐[1,4‐Bis(di­phenyl­phosphino)­butane](μ‐tetra­thio­tungstato)­palladium(II) N,N′‐di­methyl­form­amide hemisolvate hemihydrate

In the title compound, [1,4‐bis(di­phenyl­phosphino)­butane‐2κ²P,P′]­di‐μ‐thio‐1:2κ⁴S‐di­thio‐1κ²S‐palladium(II)­tung­sten(VI) N,N′‐di­methyl­form­amide hemisolvate hemihydrate, [PdWS₄­(C₂₈H₂₈P₂)]·0.5C₃H₇NO·0.5H₂O, the Pd atom is coordinated by two S atoms from the distorted‐tetrahedral [WS₄]²⁻ anion and two P atoms from the dppb mol­ecule [dppb is 1,4‐bis(di­phenyl­phos­phino)­butane] in an approximately square‐planar configuration. A puckered seven‐membered ring is formed by the Pd atom and the dppb ligand.     

3,3′‐[o‐Phenyl­enebis­(methyl­eneoxy)]­bis(6‐chloro­flavone) and 3,3′‐propyl­ene­dioxy­bis­[6‐chloro‐2‐(2‐furyl)‐4H‐1‐benzopyran‐4‐one]

The title compound 3,3′‐[o‐phenyl­enebis­(methyl­eneoxy)]­bis(6‐chloro­flavone), C₃₈H₂₄Cl₂O₆, (I), crystallizes in the monoclinic space group C2/c, with the molecules lying across twofold rotation axes so that there is half a mol­ecule in the asymmetric unit, while the other title compound, 3,3′‐propyl­ene­dioxy­bis­[6‐chloro‐2‐(2‐furyl)‐4H‐1‐benzopyran‐4‐one], C₂₉H₁₈Cl₂O₈, (II), crystallizes in monoclinic space group P2₁/n with one mol­ecule in the asymmetric unit. In both compounds, the benzopyran moiety is nearly planar, with dihedral angles between the two fused rings of 1.43 (8)° in (I), and 2.54 (7) and 3.00 (6)° with respect to the benzopyran moieties in the two halves of (II). The furan rings are twisted by 8.3 (1) and 8.4 (1)° in the two halves of (II). In both compounds, the molecular structure is stabilized by intramolecular C—H⃛O hydrogen bonds, while the crystal packing is stabilized by C—H⃛Cl and C—H⃛O intermolecular hydrogen bonds in (I) and (II), respectively.