Tej K. Razdan

Solid‐Phase One Step Synthesis of 4H,4′‐Exomethylene‐bis[quinazolin‐2‐enols]

Abstract The solid‐phase one step synthesis of 4H,4′‐exomethylene‐bis[quinazolin‐2‐enols] via 1,3‐dipolar cycloaddition of urea on benzylideneacetophenone using Sb(III) chloride impregnated alumina is described. The reaction provides 80–85% dimeric quniazolinenols. The process is convenient, cost‐effective and eco‐friendly.

Bi(NO3)3–Al2O3-Mediated Efficient Synthesis of 4-Aryl-2,6-dicoumarinylpyridines Under Solventless Conditions

A new efficient and eco-friendly methodology has been developed for the synthesis of 4-aryl-2,6-dicoumarinylpyridines from coumarinylchalcones and urea, using Bi(iii) nitrate–Al2O3 as catalyst. Coumarinylchalcones were in turn prepared from salicylaldehyde and ethylacetoacetate by the tandem reaction with aldehydes on the surface of Bi(iii) nitrate–Al2O3 in the presence of the co-catalyst Zn(ii) chloride.

ONE STEP DIMERIZATION OF LINEAR FURANOCOUMARINS

ABSTRACT The one step annular dimerisation of naturally occuring linear furanocoumarins has been effected in 70–85% yield by PPA-SiO2.

Solid-phase synthesis and crystal structure of 5(3-nitrophenyl)-3,7-diphenyl-4H,6H-1,2-diazepine

The title compound, 5-(3-nitrophenyl)-3,7-diphenyl-4H,6H-1,2-diazepine (C23H19N3O2), was synthesized, in 76% yield, by one-pot multicomponent solid-phase reaction of 3-nitrobenzylidene phenyl ketone, acetophenone and hydrazine, using the catalyst bismuth nitrate, co-catalyst ZnCl2, adsorbed on neutral alumina, at 110°C. The compound was characterized by spectral methods and X-ray diffraction studies. The crystals are monoclinic, space group P21/c: a = 12.186(2), b = 14.769(3), c = 11.046(2) Å, β = 115.023(3)°, Z = 4; R = 0.0418 for 2576 observed reflections. The diazepine ring assumes a twist chair conformation. The dihedral angles between the mean planes through the diazepine ring and the nitrophenyl rings and two phenyl are: 89.19(5)°, 45.85(5)° and 20.80(6)°, respectively. The crystal structure is stabilized by C-H…N, C-H…O, C-H…π hydrogen bonds and π-π-stacking interactions.

Conyzagenin-A and B, two new epimeric lanostane triterpenoids from Conyza canadensis

Two new epimeric lanostane triterpenoids Conyzagenin-A (1) and Conyzagenin-B (2) were isolated from roots of Conyza canadensis, along with nine known compounds (3–11). The structures of these triterpenoids were elucidated by detailed spectral methods and chemical derivatisation.