Crystal structure and Hirshfeld surface analysis of (Z)-4-oxo-4-{phen-yl[(thio-phen-2-yl)meth-yl]amino}-but-2-enoic acid.

In the title compound, C15H13NO3S, the mol-ecular conformation is stable with the intra-molecular O-H⋯O hydrogen bond forming a S(7) ring motif. In the crystal, mol-ecules are connected by C-H⋯O hydrogen bonds, forming C(8) chains running along the a-axis direction. Cohesion of the packing is provided by weak van der Waals inter-actions between the chains. A Hirshfeld surface analysis was undertaken to investigate and qu-antify the inter-molecular inter-actions. The thio-phene ring is disordered in a 0.9466 (17):0.0534 (17) ratio over two positions rotated by 180°.

Crystal structure and Hirshfeld surface analysis of dieth-yl (3aS,3a1R,4S,5S,6R,6aS,7R,9aS)-3a1,5,6,6a-tetra-hydro-1H,3H,4H,7H-3a,6:7,9a-di-epoxy-benzo[de]isochromene-4,5-di-carboxyl-ate.

In the title compound, C18H22O7, two hexane rings and an oxane ring are fused together. The two hexane rings tend toward a distorted boat conformation, while the tetra-hydro-furan and di-hydro-furan rings adopt envelope conformations. The oxane ring is puckered. The crystal structure features C-H⋯O hydrogen bonds, which link the mol-ecules into a three-dimensional network. According to a Hirshfeld surface study, H⋯H (60.3%) and O⋯H/H⋯O (35.3%) inter-actions are the most significant contributors to the crystal packing.

Influence of Substituents in a Six-Membered Chelate Ring of HG-Type Complexes Containing an N→Ru Bond on Their Stability and Catalytic Activity.

An efficient approach to the synthesis of olefin metathesis HG-type catalysts containing an N→Ru bond in a six-membered chelate ring was proposed. For the most part, these ruthenium chelates can be prepared easily and in high yields based on the interaction between 2-vinylbenzylamines and Ind II (the common precursor for Ru-complex synthesis). It was demonstrated that the increase of the steric volume of substituents attached to the nitrogen atom and in the α-position of the benzylidene fragment leads to a dramatic decrease in the stability of the target ruthenium complexes. The bulkiest iPr substituent bonded to the nitrogen atom or to the α-position does not allow the closing of the chelate cycle. N,N-Diethyl-1-(2-vinylphenyl)propan-1-amine is a limiting case; its interaction with Ind II makes it possible to isolate the corresponding ruthenium chelate in a low yield (5%). Catalytic activity of the synthesized complexes was tested in RCM reactions and compared with α-unsubstituted catalysts obtained previously. The structural peculiarities of the final ruthenium complexes were thoroughly investigated using XRD and NMR analysis, which allowed making a reliable correlation between the structure of the complexes and their catalytic properties.

Hoveyda-Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors.

A novel and efficient approach to the synthesis of 2-vinylbenzylamines is reported. This involves obtaining 2-vinylbenzylamine ligands from tetrahydroisoquinoline by alkylation and reduction followed by the Hofmann cleavage. The resultant 2-vinylbenzylamines allowed us to obtain new Hoveyda-Grubbs catalysts, which were thoroughly characterised by NMR, ESIMS, and X-ray crystallography. The utility of this chemistry is further demonstrated by the tests of the novel catalysts (up to 10-2 mol %) in different metathesis reactions such as cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening cross metathesis (ROCM).

Classical Example of Total Kinetic and Thermodynamic Control: The Diels-Alder Reaction between DMAD and Bis-furyl Dienes.

A rare example of chemospecificity in the tandem Diels-Alder reaction of activated alkynes and bis-dienes has been revealed. The reaction between bis-furyl dienes and DMAD occurs at 25-80 °C and leads to kinetically controlled "pincer" adducts, 4a,8a-disubstituted 1,4:5,8-diepoxynaphthalenes. On the contrary, only thermodynamically controlled "domino" adducts (2,3-disubstituted 1,4:5,8-diepoxynaphthalenes) are formed in the same reaction at 140 °C. The "pincer" adducts can be transformed to the "domino" adducts at heating. The rate constants for reactions of both types were calculated using dynamic 1H NMR spectroscopy.

Diels-Alder reactions between hexafluoro-2-butyne and bis-furyl dienes: kinetic versus thermodynamic control.

The tandem [4+2] cycloaddition between hexafluoro-2-butyne and bis-furyl dienes, like difurfuryl ester, at room temperature leads to the kinetically controlled "pincer"-adducts - annulated 4a,8a-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes. On the other hand, if these reactions proceed at 140 °C, only the thermodynamically controlled "domino"-adducts - annulated 2,3-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes - are formed. Therefore, a very rare and unexpected example of full kinetic and thermodynamic control in the Diels-Alder reaction is reported in this paper.

Crystal structure of methyl (3RS,4SR,4aRS,11aRS,11bSR)-5-oxo-3,4,4a,5,7,8,9,10,11,11a-deca-hydro-3,11b-ep-oxy-azepino[2,1-a]iso-indole-4-carboxyl-ate.

The title compound, C15H19NO4, is the a product of the esterification of the corresponding carbonic acid with methanol. The mol-ecule comprises a fused tetra-cyclic system containing three five-membered rings (2-pyrrolidinone, tetra-hydro-furan and di-hydro-furan) and one seven-membered ring (azepane). The five-membered rings have the usual envelope conformations, with the quaternary C atom being the flap atom for the 2-pyrrolidinone ring, and the ether O atom being the common flap atom for the remaining rings. The seven-membered azepane ring adopts a chair conformation with the methine and middle methyl-ene C atoms lying above and below the mean plane defined by the remaining five atoms. The carboxyl-ate substituent is rotated by 77.56 (5)° with respect to the base plane of the tetra-hydro-furan ring. In the crystal, the mol-ecules are bound by weak C-H⋯O hydrogen-bonding inter-actions into puckered layers parallel to (001).

rac-Methyl (3aR*,4S*,5R*,7aR*)-5,7a-bis-(acet-yloxy)-3-oxo-2-phenyl-octa-hydro-1H-iso-indole-4-carboxyl-ate.

The title molecule, C20H23NO7, the product of nucleophilic cleavage of the 3a,6-ep-oxy bridge in 1-oxo-2-phenyl-octa-hydro-3a,6-ep-oxy-iso-indole-7-carboxyl-ate, comprises a cis-fused bicyclic system containing a 2-pyrrolidinone ring in an envelope conformation (with the C atom bearing the carboxyl-ate substituent as the flap) and a cyclo-hexane ring in a chair conformation. The carboxyl-ate substituent occupies the equatorial position, whereas the two acet-yloxy substituents are in axial positions. The N atom has a trigonal-planar geometry, the sum of the bond angles being 359.3 (3)°. The dihedral angle between the mean plane of the four planar atoms of the pyrrolidinone ring and the phenyl ring is 25.98 (6)°. In the crystal, mol-ecules are linked into zigzag chains along the c-axis direction by C-H⋯O hydrogen bonds.

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a,8-hexa-hydro-4H-furo[2,3-f]isoindole-4-carb-oxy-lic acid.

The asymmetric unit of the title compound, C(17)H(15)NO(4), contains two independent mol-ecules with similar geometric parameters. In both mol-ecules, the conformation of the cyclo-hexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the α-pyrrolidinone ring as the flap. In the crystal, O-H⋯O hydrogen bonds between the carb-oxylic and carbonyl groups link alternate independent mol-ecules into chains propagating in the b-axis direction. The crystal packing also features weak C-H⋯π inter-actions.

Methyl (9aR*,10S*,11R*,13aS*,13bS*)-9-oxo-6,7,9,9a,10,11-hexa-hydro-5H,13bH-11,13a-ep-oxy-pyrrolo-[2',1':3,4][1,4]diazepino[2,1-a]isoindole-10-carboxyl-ate.

The title compound, C(17)H(18)N(2)O(4), is the methyl ester of the adduct of intra-molecular Diels-Alder reaction between maleic anhydride and 1-(2-fur-yl)-2,3,4,5-tetra-hydro-1H-pyrrolo-[1,2-a][1,4]diazepine. The mol-ecule comprises a fused penta-cyclic system containing four five-membered rings (viz. pyrrole, 2-pyrrolidinone, tetra-hydro-furan and dihydro-furan) and one seven-membered ring (1,4-diazepane). The pyrrole ring is approximately planar (r.m.s. deviation = 0.003 Å) while the 2-pyrrolidinone, tetra-hydro-furan and dihydro-furan five-membered rings have the usual envelope conformations. The central seven-membered diazepane ring adopts a boat conformation. In the crystal, mol-ecules are bound by weak inter-molecular C-H⋯O hydrogen-bonding inter-actions into zigzag chains propagating in [010]. In the crystal packing, the chains are stacked along the a axis.

Methyl 4,5-diacet-oxy-1-oxo-2-phenyl-perhydro-4,6-epoxy-cyclo-penta-[c]pyridine-7-carboxyl-ate ethanol solvate.

The title compound, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as an ethanol monosolvate, C(20)H(21)NO(8)·C(2)H(6)O. The title mol-ecule comprises a fused tricyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) in the usual envelope conformations and one six-membered ring (piperidinone) adopting a flattened twist-boat conformation.

Dimethyl 11,13-dimethyl-16-[1,2-bis-(methoxy-carbon-yl)ethen-yl]-12-oxo-16,17-dioxa-18-aza-hexa-cyclo-[7.5.1.1.1.1.0]octa-deca-2,7-diene-2,3-dicarboxyl-ate.

The title compound, C(27)H(29)NO(11), is a product of the tandem 'domino' Diels-Alder reaction. The mol-ecule comprises a fused hexa-cyclic system containing four five-membered rings (two dihydro-furan and two tetra-hydro-furan) in the usual envelope conformations and two six-membered rings (tetra-hydro-pyridinone and piperidine) adopting slightly flattened boat and chair conformations, respectively. The dispositions of the carboxyl-ate substituents relative to each other are determined by both steric reasons and inter-molecular C-H⋯O hydrogen bonding and attractive anti-parallel C=O⋯C=O inter-actions [C⋯O = 2.995 (2) Å].

Methyl 7,8-diacet-oxy-11-oxo-5-(2-oxo-pyrrolidin-1-yl)-7,9-epoxy-cyclo-penta-[4,5]pyrido[1,2-a]quinoline-10-carboxyl-ate sesquihydrate.

The title compound, C(26)H(28)N(2)O(9)·1.5H(2)O, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol-ecules occupying a special position on a twofold axis. The organic mol-ecule comprises a fused penta-cyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) and three six-membered rings (piperidinone, tetra-hydro-pyridine and benzene). The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetra-hydro-pyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O-H⋯O hydrogen bonds, which link the organic mol-ecules and water mol-ecules into complex two-tier layers parallel to (001). The layers are further linked into a three-dimensional framework by attractive inter-molecular carbon-yl-carbonyl inter-actions.