Sibdas Ray

Synthesis and crystal structures of 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole

Both 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide (AHIC) and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole (ACCI) have been synthesized and crystallized in the monoclinic space group P21/c, Z = 4, with a = 8.420(2), b = 9.759(2), c = 10.583(2) Å, β = 111.80(2)° for AHIC and a = 6.139(1), b = 8.522(2), c = 15.156(3) Å, β = 96.71(2)° for ACCI. Differences in the molecular geometries of the two compounds are attributed to the differences in the substituents at the 1- and 4-positions of the imidazole ring. The molecular conformation of AHIC is stabilized by intramolecular hydrogen bonding between the 5-amino and the vicinal carboxamide moiety, resulting in an extended planar structural pattern. The presence of the cyano group in the 4-position of ACCI prevents the formation of such an intramolecular hydrogen bond. Both the crystal structures are stabilized by networks of intermolecular hydrogen bonds.

Synthesis of Benz[d]oxazolones Involving Concomitant Acetyl Migration from Oxygen to Nitrogen

Heating of o-acetoxybenzoyl azides 6–10 in toluene leads to the Curtius reaction, which, when followed by closure of oxazolone ring with concomitant migration of acetyl group from oxygen to nitrogen, produces 3-acetoxybenz[d]oxazol-2(3H)-ones 11–15, which undergo hydrolysis with hot dilute hydrochloric acid to furnish benz[d]oxazol-2(3H)-ones 17–21. Thermal reaction of 2-hydroxy-5-nitrobenzoyl azide (22) in toluene finally yields a mixture of 5-nitrobenz[d]oxazol-2(3H)-one (20) and 5-nitrobenz[d]isoxazol-3(2H)-one (23).

Novel Sulfur‐to‐Nitrogen Migration of Ethenylmethyl Moiety in Benz[d]oxazole System via Internal Radical Capture

Abstract 2‐Ethenylmethylthiobenz[d]oxazoles 9–11, on heating at high temperature in bromobenzene, underwent migration of ethenylmethyl moieties without rearrangement from sulfur to nitrogen in an internal radical capture pathway, instead of [3,3]‐sigmatropic change, to furnish 3‐ethenylmethylbenz[d]oxazole‐2(3H)‐thiones 13–15.

5-Amino-1-[2-(diethylamino)ethyl]-1H-imidazole-4-carboxamide

Intramolecular hydrogen bonds influence the molecular conformation of the title compound, C 10 H 19 N 5 O, resulting in an extended planar hydrogen-bonded heterocyclic ring structure. The bulky diethylaminoethyl group adopts a butterfly conformation. The stabilization of the crystal structure is supported by an extensive network of intermolecular hydrogen bonds.

5-Amino-1-benzyl-4-cyano-3-methylimidazolium toluene-p-sulfonate

The title compound, C12H13N4+·C7H7O3S−, contains an imidazolium cation and a toluene-p-sulfonate anion in the asymmetric unit. Hydrogen-bonded dimers are formed between the cyano and amino groups of inversion-related imidazolium cations.

Putative Pheromone of the Indian Crestless Porcupine, Hystrix brachyura

The study on behavior and chemical analysis of urinary pheromone of Indian Porcupine, Hystrix brachyura (Linn. 1758) was performed during 2011–2014 in different phases at a rehabilitation Center near Kolkata, India. Ethological data based on five porcupines, including both male and female in different combinations revealed that urine and feces are deposited non-randomly at specific sites. The male collected urine in the hollow quills of the tail and sprayed it nearby for transmission of chemical information for social interactions. Males also sniffed and licked female urine. We identified urine and hollow quill, as the possible vectors of transmission of this information. Phenol, cresol and phenylacetylene were identified from the hexane extract of female urine and benzaldehyde, cresol and methyl cyclohexane from the male urine by Gas Chromatography Mass Spectrometry (GCMS). Two isomeric compounds o- and p-cresol were identified from both the sexes by High Performance Liquid Chromatography. Thin Layer Chromatography showed the presence of triglycerides and diglycerides in the urine which might act as fixatives.

Synthetic and Thermogravimetric Studies of 5-Amino-2-ethoxycarbonylaminothiazoles

Abstract 5-Amino-4-cyano-2-ethoxycarbonylaminothiazole (2), 2-ethoxycarbonylaminothiazolo[5,4-d]pyrimidine-7(6H)-one (4), and 5-ethoxymethyleneamino-4-cyano-2-ethoxycarbonylaminothiazole-4-carboxamide (9) were synthesized from 5-amino-2-ethoxycarbonylaminothiazole-4-carboxamide (1). Unlike simple 5-aminothiazoles, 1 and 2 did not undergo rearrangement in hot aqueous alkali, because of the role of their 2-ethoxycarbonylamino substituents. Thermogravimetric experiments on 1, 2, 4, and 9 revealed routine elimination of ethanol molecule from the NHCO 2C2H5 substituent of 1, 2, 4, and 9. GRAPHICAL ABSTRACT

Synthesis and crystal structure of (5-amino-4-carboxamidoimidazol-1-yl) acetamide, a possible PDE inhibitor

The crystal structure of 2-(5-amino-4-carboxamidoimidazol-1-yl)acetamide has been determined from X-ray diffractometric data, and refined to anR-value of 0.057 with 1179 observed reflections. Intramolecular hydrogen bonding between the 5-amino group and the vicinal carboxamide moiety stabilizes the molecular conformation and forms an extended planar structural pattern.