D. Kannan

Solid-state melt reaction for the domino process: highly efficient synthesis of fused tetracyclic chromenopyran pyrimidinediones using Baylis-Hillman derivatives.

A solid-state melt reaction (SSMR) has been demonstrated via a domino process for the synthesis of tetracyclic chromenopyran pyrimidinedione frameworks using Baylis-Hillman derivatives through in situ formation of an olefin followed by an intramolecular [4 + 2] cycloaddition reaction sequence. The tetracyclic frameworks were obtained without using catalyst and solvent in a highly stereoselective and stereospecific fashion. The isolated yield is excellent and does not require column chromatography purification to obtain the pure product.

A multicomponent cascade reaction for the synthesis of novel chromenopyranpyrazole scaffolds

A catalyst, solvent, work-up and column free synthesis of chromenopyranpyrazoles via multicomponent cascade reaction has been achieved with high stereoselectivity. This novel reaction creates two N-C, two C-C and one O-C bonds through a domino process for the construction of three new rings and three contiguous stereogenic centers.

A novel synthesis of tetra and pentacyclic quinolinopyran tethered pyrazole/coumarin scaffolds via a solid state melt reaction

A new protocol has been developed for the efficient synthesis of structurally diverse tetra- and pentacyclic quinolinopyran tethered pyrazole/coumarin architectures via a domino Knoevenagel intramolecular hetero-Diels–Alder (IMHDA) strategy using a solid state melt reaction (SSMR) in a highly diastereo and regioselective fashion. Gratifyingly, these heterocyclic frameworks were synthesized under solvent and catalyst free conditions, without the aid of a work-up and column chromatography purification. The generality and functional tolerance of this convergent and environmentally benign method is very attractive.

Methyl (Z)-2-{[N-(2-formyl-phen-yl)-4-methyl-benzene-sulfonamido]-meth-yl}-3-phenyl-prop-2-enoate.

In the title compound, C25H23NO5S, the sulfonyl-bound benzene ring forms dihedral angles of 37.2 (1) and 67.0 (1)°, respectively, with the formylphenyl and phenyl rings. The molecular conformation is stabilized by an intramolecular C—H⋯π interaction. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming a two-dimensional network in the (110) plane in which R 4 4(38) ring motifs are generated.

Methyl 11,14,16-triphenyl-8,12-dioxa-14,15-di-aza-tetra-cyclo-[8.7.0.0(2,7).0(13,17)]hepta-deca-2(7),3,5,13(17),15-penta-ene-10-carboxyl-ate.

In the title compound, C33H26N2O4, the pyrazole ring makes dihedral angles of 15.13 (7) and 60.80 (7)° with the adjacent phenyl rings. Both dihydropyran rings exhibit half-chair conformations. A weak intramolecular C—H⋯O interaction occurs. In the crystal, molecules are linked into inversion dimers through pairs of C—H⋯N interactions. Weak C—H⋯π interactions are also observed.

N-(2-Formyl­phen­yl)-4-toluene­sulfonamide: a second monoclinic polymorph

The title compound, C14H13NO3S, (I), is a second monoclinic polymorph. The original polymorph, (II), was reported by Mahía et al. [Acta Cryst. (1999), C55, 2158–2160]. Polymorph (II) crystalllized in the space group P21/c (Z = 4), whereas the title polymorph (I) occurs in the space group P21/n (Z = 4). The dihedral angle between the two aromatic rings is 75.9 (1)° in (I) compared to 81.9 (1)° for (II). In both polymorphs, two S(6) rings are generated by intramolecular N—H⋯O and C—H⋯O hydrogen bonds, resulting in similar molecular geometries. However, the two polymorphs differ concerning their crystal packing. In (I), molecules are linked into C(8) zigzag chains along the b axis by C—H⋯O hydrogen bonds, whereas in (II) molecules are linked by C—H⋯O hydrogen bonds, forming C(7) chains along the b axis. The title polymorph is further stabilized by intermolecular C—H⋯π and π–π interactions [centroid–centroid distance = 3.814 (1) Å]. These interactions are not evident in polymorph (II).

Methyl (Z)-2-[(2,4-dioxothia-zolidin-3-yl)meth-yl]-3-(2-methyl-phen-yl)prop-2-enoate.

The C=C bond in the title compound, C15H15NO4S, has a Z configuration. The thiazolidine ring is essentially planar [maximum deviation = 0.008 (1) Å for the N atom] and is oriented at a dihedral angle of 59.1 (1)° with respect to the benzene ring. In the crystal, pairs of C—H⋯O hydrogen bonds link centrosymmetrically related molecules into dimers, generating R 2 2(18) ring motifs. The crystal packing is further stabilized by C—H⋯π and C—O⋯π [O⋯centroid = 3.412 (2) Å and C—O⋯centroid = 115.0 (1)°] interactions.

Methyl (2Z)-2-{[N-(2-formyl-phen-yl)-4-methyl-benzene-sulfonamido]-meth-yl}-3-(naphthalen-1-yl)prop-2-enoate.

In the title compound, C29H25NO5S, the sulfonyl-bound benzene ring forms dihedral angles of 42.1 (1) and 48.5 (1)°, respectively, with the formyl-substituted benzene ring and the naphthalene residue. In the crystal, pairs of C—H⋯O interactions lead to the formation of R 2 2(10) inversion dimers, which are linked by further C—H⋯O interactions into supramolecular tapes running along [100]. The crystal packing is further stabilized by C—H⋯π interactions.

16-Methyl-11-(2-methyl­phen­yl)-14-phenyl-8,12-dioxa-14,15-di­aza­tetra­cyclo­[8.7.0.02,7.013,17]hepta­deca-2(7),3,5,13(17),15-penta­ene-10-carbo­nitrile

In the title compound, C28H23N3O2, the pyrazole ring makes a dihedral angle of 16.90 (6)° with the phenyl ring to which it is attached. Both dihydropyran rings exhibit half-chair conformations. Intramolecular C—H⋯O interactions generate S(6) and S(8) ring motifs. In the crystal, weak C—H⋯O and C—H⋯π interactions occur.

(Z)-3-(4-Chloro-phen-yl)-2-{[N-(2-formyl-phen-yl)-4-methyl-benzene-sulfonamido]-meth-yl}prop-2-ene-nitrile.

In the title compound, C24H19ClN2O3S, the sulfonyl-bound benzene ring forms dihedral angles of 38.1 (2) and 81.2 (1)°, respectively, with the formyl benzene and benzene rings. The molecular conformation is stabilized by a weak intramolecular C—H⋯O hydrogen bond, which generates an S(5) ring motif. The crystal packing is stabilized by C—H⋯O hydrogen bonds, which generate C(7) zigzag chains along [010] and R 3 3(19) ring motifs along [010]. The crystal packing is further stabilized by C—Cl⋯π interactions [Cl⋯centroid = 3.456 (2) Å and C—Cl⋯centroid = 173.4 (2)°].