A hydrogen‐bonded chain of rings in 5‐amino‐1‐(4‐methoxybenzoyl)‐3‐methylpyrazole and a three‐dimensional hydrogen‐bonded framework in 5‐amino‐3‐methyl‐1‐(2‐nitrobenzoyl)pyrazole

The molecules of 5‐amino‐1‐(4‐methoxybenzoyl)‐3‐methylpyrazole, C₁₂H₁₃N₃O₂, (I), and 5‐amino‐3‐methyl‐1‐(2‐nitrobenzoyl)pyrazole, C₁₁H₁₀N₄O₃, (II), both contain intramolecular N—H...O hydrogen bonds. The molecules of (I) are linked into a chain of rings by a combination of N—H...N and N—H...π(arene) hydrogen bonds, while those of (II) are linked into a three‐dimensional framework structure by N—H...N and C—H...O hydrogen bonds.     

Microwave-assisted synthesis of fused pyrazolo[3,4-b]pyrazines by the reaction of ortho-aminonitrosopyrazoles and cyclic β-diketones

Novel fused pyrazolo[3,4-b]pyrazines 3 were prepared by assisted microwave cyclocondensation reaction of ortho-aminonitrosopyrazoles 1 and cyclic β-diketones 2 in dimethylformamide. This protocol provides a simple procedure for the synthesis of the title compounds with the advantages of easy work-up, mild reaction conditions and good yields.     

Three-component synthesis of hexahydropyridopyrimidine-spirocyclohexanetriones induced by microwave

Pyridopyrimidine-spirocyclohexanetriones (5, 6) and pyrimido[4,5-b]quinolinones (8) were obtained in a three-component microwave-assisted reaction of 6-aminopyrimidin-4-ones (1) with dimedone (2) and formaldehyde solution or paraformaldehyde, respectively. A mechanism is proposed based on the presence of a basic catalyst (triethylamine in this case) and the fact that single condensation intermediates are isolated prior to the cyclization leading to the final products.     

Regioselective synthesis of novel 4-aryl-2-ethylthio-7-methyl pyrazolo[1,5-a]-[1,3,5]-triazines

Pyrazolo[1,5-a]-[1,3,5]-triazines 6a-d were obtained by an efficient one-step reaction from S,S-diethyl aroyliminodithiocarbonates 4a-d and 5-amino-3-methylpyrazole 5 or by an alternative two-step reaction from 5 and aroyl isothiocyanates 8a-d to give initially the thiourea derivatives 9a-d, which after S-ethylation and cyclization afforded compounds 6a-d. The intermediate 7a isolated from reaction between 4a and 5 permitted us to establish the orientation.     

Microwave‐assisted three‐component synthesis and in vitro antifungal evaluation of 6‐cyano‐5,8‐dihydropyrido[2,3‐d]pyrimidin‐4(3H)‐ones

The reaction of 6‐aminopyrimidin‐4‐ones 1 with benzaldehydes 2 and β‐aminocrotononitrile 3 or benzoylacetonitrile 4 under microwave irradiation in dry media yields the 6‐cyano‐5,8‐dihydropyrido[2,3‐d]‐pyrimidinones 5a‐t . The structure of the synthesized compounds was determined on the basis of nmr measurements, especially by ¹H,¹H?, ¹H,¹³C COSY, DEPT and NOESY experiments. In contrast with other pyrido‐[2,3‐d]pyrimidine derivatives, these compounds did not show any antifungal in vitro activity up to 250 μg/mL.     

Microbial transformation of two 15α-hydroxy-ent-kaur-16-ene diterpenes by Mucor plumbeus

The microbiological transformation of candidiol (15α,18-dihydroxy-ent-kaur-16-ene) by Mucor plumbeus led to 3β,15α,18-trihydroxy-ent-kaur-16-ene, 6α,15α,18-trihydroxy-ent-kaur-16-ene, 3α,15α,18-trihydroxy-ent-kaur-16-ene, 11β,15α,18-trihydroxy-ent-kaur-16-ene and 15α,17,18-trihydroxy-11β,16β-epoxy-ent-kaurane, whilst the incubation of 15α,19-dihydroxy-ent-kaur-16-ene gave 9β,15α,19-trihydroxy-ent-kaur-16-ene, 3α,15α,19-trihydroxy-ent-kaur-16-ene, 11β,15α,19-trihydroxy-ent-kaur-16-ene, 6α,15α,19-trihydroxy-ent-kaur-16-ene, 15α,17,19-trihydroxy-11β,16β-epoxy-ent-kaurane, 19-(β-d-glucopyranosyl)-15α-hydroxy-ent-kaur-16-ene and 19-(β-d-glucopyranosyl)-15-oxo-ent-kaur-16-ene. An interesting rearrangement in dilute acid medium of 9β,15α,19-trihydroxy-ent-kaur-16-ene into 16-oxo-19-hydroxy-ent-abiet-8(9),15-diene, is also described in this work.     

Preparation of 6-chloropyrazolo[3,4-b]pyridine-5-carbaldehydes by Vilsmeier-Haack reaction and its use in the synthesis of heterocyclic chalcones and dipyrazolopyridines

Novel 6-chloropyrazolo[3,4-b]pyridine-5-carbaldehydes 5 have been synthesized from the 4,5-dihydropyrazolo[3,4-b]pyridine-6-ones 4 via Vilsmeier-Haack reaction. Further treatment of carbaldehydes 5 with acetophenones 6 and hydrazine hydrate afforded chalcone analogues 7 and dipyrazolo[3,4-b:4′,3′-e]pyridines 8, respectively.     

Two-step demodulation based on the Gram-Schmidt orthonormalization method

This Letter presents an efficient, fast, and straightforward two-step demodulating method based on a Gram-Schmidt (GS) orthonormalization approach. The phase-shift value has not to be known and can take any value inside the range (0,2π), excluding the singular case, where it corresponds to π. The proposed method is based on determining an orthonormalized interferogram basis from the two supplied interferograms using the GS method. We have applied the proposed method to simulated and experimental interferograms, obtaining satisfactory results. A complete MATLAB software package is provided at http://goo.gl/IZKF3.