Molecules

161 KiB

Open AccessArticle

2-Arylhydrazonopropanals as Building Blocks in Heterocyclic Chemistry: Microwave Assisted Condensation of 2-Arylhydrazonopropanals with Amines and Active Methylene Reagents

by Khadijah M. Al-Zaydi, Rita M. Borik and Mohamed H. Elnagdi

Molecules 2003, 8(12), 910-923; https://doi.org/10.3390/81200910 - 31 Dec 2003

Cited by 33 | Viewed by 10905

Abstract

Utilization of 2-arylhydrazonopropanals for the synthesis of 2-arylhydrazonoimino propanones, 1,2,4-trizolo[4,3-a]pyrimidines, pyridopyridazine hydrazones, 3-oxaloalkanonitriles and 1,2,3-trizole derivatives by conventional heating and under microwave irradiation is described. Structural assignments are based on spectroscopic data and confirmed in some cases by X-ray crystallography. Full article

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59 KiB

Open AccessArticle

New Bioactive Azaartemisinin Derivatives

by Mai M. Al-Oqail, Ahmed M. Galal, Mohamed S. Ahmad, Ahlam M. Al-Fishawi and Farouk S. El-Feraly

Molecules 2003, 8(12), 901-909; https://doi.org/10.3390/81200901 - 31 Dec 2003

Cited by 15 | Viewed by 11689

Abstract

Reaction of artemisinin (1) with ethanolamine, followed by acid treatment produced the lactam (4S,8S,9S,13S,1R,5R,12R)-11-aza-11-(2-hydroxyethyl)-1,5,9-trimethyl-14,15-dioxatetracyclo [10.2.1.0.0]pentadecan-10-one (4) and the diol (1S,2S,6S,7S,5R,8R)-4-aza-5,6-dihydroxy-4-(2-hydroxyethyl)-2,8-dimethyl-7-(3-oxobutyl) bicyclo[4.4.0]decan-3-one (7). When ethylenediamine was used instead of the ethanolamine, the dimeric lactam (1S,4S,8S,9S,13S,5R,12R)-11-[2-((1S,4S,8S,9S,13S,5R,12R)-11-aza-1,5,9-trimethyl-14,15-dioxa-10-oxotetracyclo[10.2.1.0.0] pentadec-11-yl)ethyl]-11-aza-1,5,9-tri-methyl-14,15-dioxatetracyclo-[10.2.1.0.0]-pentadecan-10-one (8) was obtained. All compounds are new azaartemisinin [...] Read more.

Reaction of artemisinin (1) with ethanolamine, followed by acid treatment produced the lactam (4S,8S,9S,13S,1R,5R,12R)-11-aza-11-(2-hydroxyethyl)-1,5,9-trimethyl-14,15-dioxatetracyclo [10.2.1.0<4,13>.0<8,13>]pentadecan-10-one (4) and the diol (1S,2S,6S,7S,5R,8R)-4-aza-5,6-dihydroxy-4-(2-hydroxyethyl)-2,8-dimethyl-7-(3-oxobutyl) bicyclo[4.4.0]decan-3-one (7). When ethylenediamine was used instead of the ethanolamine, the dimeric lactam (1S,4S,8S,9S,13S,5R,12R)-11-[2-((1S,4S,8S,9S,13S,5R,12R)-11-aza-1,5,9-trimethyl-14,15-dioxa-10-oxotetracyclo[10.2.1.0<4,13>.0<8,13>] pentadec-11-yl)ethyl]-11-aza-1,5,9-tri-methyl-14,15-dioxatetracyclo-[10.2.1.0<4,13>.0<8,13>]-pentadecan-10-one (8) was obtained. All compounds are new azaartemisinin derivatives lacking the peroxide functionality. These compounds were evaluated for antimalarial and cytotoxic activities. Only the dimer 8 was found to possess antimalarial activity, while only the diol 7 exhibited cytotoxic activity against human breast ductal carcinoma. Full article

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94 KiB

Open AccessArticle

Synthesis and Characterization of Benzo-15-Crown-5 Ethers with Appended N₂O Schiff Bases

by Carla Sousa, Cristina Freire and Baltazar De Castro

Molecules 2003, 8(12), 894-900; https://doi.org/10.3390/81200894 - 31 Dec 2003

Cited by 74 | Viewed by 12221

Abstract

New derivatives of benzo-15-crown-5 with flexible appended N₂O unsymmetrical Schiff bases were prepared by a two step procedure which involves: (i) preparation of N₂O Schiff bases by condensation of hydrazine with salicylaldehyde, 3-methoxysalicylaldehyde or 2-hydroxy-1-naphtaldehyde and (ii) reaction of [...] Read more.

New derivatives of benzo-15-crown-5 with flexible appended N₂O unsymmetrical Schiff bases were prepared by a two step procedure which involves: (i) preparation of N₂O Schiff bases by condensation of hydrazine with salicylaldehyde, 3-methoxysalicylaldehyde or 2-hydroxy-1-naphtaldehyde and (ii) reaction of the resulting NH₂ functionalized compounds with 4-formyl-benzo-15-crown-5. Full article

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156 KiB

Open AccessArticle

Epoxidation of Diosgenin, 25(R)-1,4,6-Spirostatrien-3-one and 25(R)-4,6-Spirostadien-3β-ol

by Eunsook Ma and Jongwon Kim

Molecules 2003, 8(12), 886-893; https://doi.org/10.3390/81200886 - 31 Dec 2003

Cited by 14 | Viewed by 11791

Abstract

Upon treatment of 25(R)-spirost-5-en-3β-ol (diosgenin), 25(R)-1,4,6-spirostatrien-3-one and 25(R)-4,6-spirostadien-3β-ol with 30% H₂O₂ and 5% NaOH in methanol, diosgenin did not react, 25(R)-1,4,6-spirostatrien-3-one was converted to 25(R)-1α,2α-epoxy-4,6-spirostadien-3-one and 25(R)-4,6-spirostadien-3β-ol was oxidized to give a small amount of 25(R)-4,6-spirostadien-3-one, while most of the [...] Read more.

Upon treatment of 25(R)-spirost-5-en-3β-ol (diosgenin), 25(R)-1,4,6-spirostatrien-3-one and 25(R)-4,6-spirostadien-3β-ol with 30% H₂O₂ and 5% NaOH in methanol, diosgenin did not react, 25(R)-1,4,6-spirostatrien-3-one was converted to 25(R)-1α,2α-epoxy-4,6-spirostadien-3-one and 25(R)-4,6-spirostadien-3β-ol was oxidized to give a small amount of 25(R)-4,6-spirostadien-3-one, while most of the original starting material remained unchanged. On the other hand, reactions of diosgenin, 25(R)-1,4,6-spirostatrien-3-one and 25(R)-4,6-spirostadien-3β-ol with m-chloroperoxybenzoic acid in chloroform yielded 25(R)-5α,6α-epoxyspirostan-3β-ol, 25(R)-6α,7α-epoxy-1,4-spirostadien-3-one and 25(R)-4β,5β-epoxy-6-spirosten-3β-ol, respectively. Full article

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45 KiB

Open AccessArticle

A Carboxylic Acid from Ilex integra

by Motoo Tori, Yoshie Mukai, Katsuyuki Nakashima and Masakazu Sono

Molecules 2003, 8(12), 882-885; https://doi.org/10.3390/81200882 - 31 Dec 2003

Cited by 3 | Viewed by 7056

Abstract

(12E,14E,17E)-11-Hydroxy-12,14,17-dodecatrienoic acid was isolated from the stems of Ilex integra and its structure was determined on the basis of the spectroscopic data of its methyl ester. Full article

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49 KiB

Open AccessArticle

Silane Reduction of 5-Hydroxy-6-methyl-pyridine-3,4-dicarboxylic Acid Diethyl Ester: Synthesis of Vitamin B₆

by Yves René Dumond and Andrew G. Gum

Molecules 2003, 8(12), 873-881; https://doi.org/10.3390/81200873 - 31 Dec 2003

Cited by 11 | Viewed by 11494

Abstract

Alternative methods for the synthesis of pyridoxine have been investigated. The key intermediate, 5-hydroxy-6-methyl-pyridine-3,4-dicarboxylic acid diethyl ester (5), was reduced with either a silane monomer (MeSiH(OEt)₂) or a polysiloxane (polymethylhydrosiloxane, PMHS) to afford crude pyridoxine. An isolation technique utilizing a commercially [...] Read more.

Alternative methods for the synthesis of pyridoxine have been investigated. The key intermediate, 5-hydroxy-6-methyl-pyridine-3,4-dicarboxylic acid diethyl ester (5), was reduced with either a silane monomer (MeSiH(OEt)₂) or a polysiloxane (polymethylhydrosiloxane, PMHS) to afford crude pyridoxine. An isolation technique utilizing a commercially available resin was devised, affording the desired product, vitamin B₆, in an overall yield of 38-54 % and a purity of 76%. Full article

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310 KiB

Open AccessArticle

Synthesis and Crystal Structure of Hexakis(imidazole) nickel (II) O,O′-diphenyldithiophosphate [Ni(Im)₆](Ph₂O₂PS₂)₂

by Shusheng Zhang, Shiying Wang, Yonghong Wen and Kui Jiao

Molecules 2003, 8(12), 866-872; https://doi.org/10.3390/81200866 - 31 Dec 2003

Cited by 6 | Viewed by 10040

Abstract

The crystal and molecular structures of [Ni(Im)₆](dtp)₂ (Im = imidazole, dtp = O,O′-diphenyldithiophosphate) have been determined by X-ray crystallography. It crystallizes in the triclinic system, space group Pī, with cell parameters a = 9.375 (2), b = 12.324(3), c = [...] Read more.

The crystal and molecular structures of [Ni(Im)₆](dtp)₂ (Im = imidazole, dtp = O,O′-diphenyldithiophosphate) have been determined by X-ray crystallography. It crystallizes in the triclinic system, space group Pī, with cell parameters a = 9.375 (2), b = 12.324(3), c = 13.285(3) Å, α = 107.86(3), β = 102.28(3), γ = 109.24(3), and Z = 1. The crystal structure of the title compound is built up of discrete monomeric molecules of [Ni(Im)₆](dtp)₂. The nickel (II) ion is hexacoordinated by six imidazole molecules and the coordination environment of Ni (II) is of octahedral geometry. In the solid state, a network of N-H···S intermolecular hydrogen bonds connect the Ni(Im)₆ moieties and O,O′-diphenyldithiophosphate molecules, forming a three-dimensional structure. Full article

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Molecules, Volume 8, Issue 12 (December 2003) – 7 articles , Pages 866-923

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