The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Hossein Reza Darabi - One of the best experts on this subject based on the ideXlab platform.
-
Naturally occurring organic acids for organocatalytic Synthesis of Pyrroles via Paal–Knorr reaction
Research on Chemical Intermediates, 2020Co-Authors: Farshid Mohsenzadeh, Kioumars Aghapoor, Hossein Reza Darabi, Mahsa Alivand, Yadollah BalavarAbstract:In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr Pyrrole Synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60 °C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the Synthesis of Pyrrole scaffolds. Graphic abstract
-
Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr Pyrrole Synthesis: a safe, expeditious, and sustainable protocol
Research on Chemical Intermediates, 2018Co-Authors: Kioumars Aghapoor, Farshid Mohsenzadeh, Hossein Reza Darabi, Saeed RastgarAbstract:Among various alkali (Na, K) and alkaline-earth (Ca, Mg, Sr, Ba) chlorides, calcium(II) chloride was found to be a cost-effective Lewis acid catalyst for solvent-free Synthesis of Pyrroles from primary aromatic and aliphatic amines under open-vessel focused microwave irradiation. The salient features of this environmentally benign method are high to quantitative conversion, short reaction time, safe and clean reaction profile, possibility of scale-up to multigram quantities, and use of a low-cost, widely available, nontoxic catalyst. Graphical abstract
-
l-Tryptophan-catalyzed Paal–Knorr Pyrrole cyclocondensation: an efficient, clean and recyclable organocatalyst
Research on Chemical Intermediates, 2016Co-Authors: Kioumars Aghapoor, Hani Sayahi, Farshid Mohsenzadeh, Hossein Reza Darabi, Yadollah BalavarAbstract:A simple, clean, and efficient solvent-free protocol is introduced for Paal–Knorr Pyrrole Synthesis catalyzed by l -tryptophan as a thermally resistant, natural primary amino acid. The products were obtained mostly in excellent yields through the reaction of hexane-2,5-dione with aromatic primary amines bearing a variety of substituents. The catalyst could be easily isolated from the reaction mixture and recycled at least six times without significant loss of activity. The procedure has an environmentally benign nature in agreement with the concepts of green chemistry.
-
Catalytic activity of the nanoporous MCM-41 surface for the Paal–Knorr Pyrrole cyclocondensation
Zeitschrift für Naturforschung B, 2015Co-Authors: Kioumars Aghapoor, Khosrow Jadidi, Farshid Mohsenzadeh, Mostafa M Amini, Hossein Reza DarabiAbstract:AbstractThe investigation of different oxide surfaces revealed that nanoporous silica (MCM-41) had the best catalytic activity for Paal–Knorr Pyrrole Synthesis. Despite the same composition, MCM-41 proved to be more effective than SiO2 itself, probably due to a significantly higher surface area of the SiO2 nanopores. The important features of this “clean” solvent-free protocol are the ease of recovery and the reuse of the catalyst for several cycles, operational simplicity, and easy product isolation and purification.
-
Vitamin B_1 as a metal-free organocatalyst for greener Paal–Knorr Pyrrole Synthesis
Environmental Chemistry Letters, 2012Co-Authors: Hossein Reza Darabi, Abbas Darestani Farahani, Kioumars Aghapoor, Farshid MohsenzadehAbstract:This investigation discloses a greener reaction to prepare Pyrrole derivatives. Metal-free catalysts are greener alternatives to existing metal catalysts in synthetic organic chemistry. Indeed, transition metals are often costly and toxic. They may be found as traces in health reaction products such as pharmaceuticals. Alternatively small organic molecules termed “organocatalysts” allow the Synthesis of valuable products without traces of toxic metals. Here, we show for the first time the use of vitamin B_1 as new organocatalyst for the Paal–Knorr Pyrrole Synthesis under ambient conditions. Reaction conditions were optimized for the reaction of hexane-2,5-dione with 4-methoxyaniline. Ethanol was the most effective solvent. The conversion was quantitative using vitamin B_1, by comparison with a low yield of 30 % without catalysis. The best conditions were performed in ethanol with 5 mol % of vitamin B_1 during 1 h. This reaction was tested using various aromatic amines. To conclude the use of vitamin B_1 for the Paal–Knorr Pyrrole, cyclocondensation has mild reaction conditions, is simple to perform, and gives moderate to excellent yields. It is therefore a promising reaction for the preparation of various Pyrrole derivatives.
Farshid Mohsenzadeh - One of the best experts on this subject based on the ideXlab platform.
-
Naturally occurring organic acids for organocatalytic Synthesis of Pyrroles via Paal–Knorr reaction
Research on Chemical Intermediates, 2020Co-Authors: Farshid Mohsenzadeh, Kioumars Aghapoor, Hossein Reza Darabi, Mahsa Alivand, Yadollah BalavarAbstract:In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr Pyrrole Synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60 °C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the Synthesis of Pyrrole scaffolds. Graphic abstract
-
Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr Pyrrole Synthesis: a safe, expeditious, and sustainable protocol
Research on Chemical Intermediates, 2018Co-Authors: Kioumars Aghapoor, Farshid Mohsenzadeh, Hossein Reza Darabi, Saeed RastgarAbstract:Among various alkali (Na, K) and alkaline-earth (Ca, Mg, Sr, Ba) chlorides, calcium(II) chloride was found to be a cost-effective Lewis acid catalyst for solvent-free Synthesis of Pyrroles from primary aromatic and aliphatic amines under open-vessel focused microwave irradiation. The salient features of this environmentally benign method are high to quantitative conversion, short reaction time, safe and clean reaction profile, possibility of scale-up to multigram quantities, and use of a low-cost, widely available, nontoxic catalyst. Graphical abstract
-
l-Tryptophan-catalyzed Paal–Knorr Pyrrole cyclocondensation: an efficient, clean and recyclable organocatalyst
Research on Chemical Intermediates, 2016Co-Authors: Kioumars Aghapoor, Hani Sayahi, Farshid Mohsenzadeh, Hossein Reza Darabi, Yadollah BalavarAbstract:A simple, clean, and efficient solvent-free protocol is introduced for Paal–Knorr Pyrrole Synthesis catalyzed by l -tryptophan as a thermally resistant, natural primary amino acid. The products were obtained mostly in excellent yields through the reaction of hexane-2,5-dione with aromatic primary amines bearing a variety of substituents. The catalyst could be easily isolated from the reaction mixture and recycled at least six times without significant loss of activity. The procedure has an environmentally benign nature in agreement with the concepts of green chemistry.
-
Catalytic activity of the nanoporous MCM-41 surface for the Paal–Knorr Pyrrole cyclocondensation
Zeitschrift für Naturforschung B, 2015Co-Authors: Kioumars Aghapoor, Khosrow Jadidi, Farshid Mohsenzadeh, Mostafa M Amini, Hossein Reza DarabiAbstract:AbstractThe investigation of different oxide surfaces revealed that nanoporous silica (MCM-41) had the best catalytic activity for Paal–Knorr Pyrrole Synthesis. Despite the same composition, MCM-41 proved to be more effective than SiO2 itself, probably due to a significantly higher surface area of the SiO2 nanopores. The important features of this “clean” solvent-free protocol are the ease of recovery and the reuse of the catalyst for several cycles, operational simplicity, and easy product isolation and purification.
-
Vitamin B_1 as a metal-free organocatalyst for greener Paal–Knorr Pyrrole Synthesis
Environmental Chemistry Letters, 2012Co-Authors: Hossein Reza Darabi, Abbas Darestani Farahani, Kioumars Aghapoor, Farshid MohsenzadehAbstract:This investigation discloses a greener reaction to prepare Pyrrole derivatives. Metal-free catalysts are greener alternatives to existing metal catalysts in synthetic organic chemistry. Indeed, transition metals are often costly and toxic. They may be found as traces in health reaction products such as pharmaceuticals. Alternatively small organic molecules termed “organocatalysts” allow the Synthesis of valuable products without traces of toxic metals. Here, we show for the first time the use of vitamin B_1 as new organocatalyst for the Paal–Knorr Pyrrole Synthesis under ambient conditions. Reaction conditions were optimized for the reaction of hexane-2,5-dione with 4-methoxyaniline. Ethanol was the most effective solvent. The conversion was quantitative using vitamin B_1, by comparison with a low yield of 30 % without catalysis. The best conditions were performed in ethanol with 5 mol % of vitamin B_1 during 1 h. This reaction was tested using various aromatic amines. To conclude the use of vitamin B_1 for the Paal–Knorr Pyrrole, cyclocondensation has mild reaction conditions, is simple to perform, and gives moderate to excellent yields. It is therefore a promising reaction for the preparation of various Pyrrole derivatives.
Kioumars Aghapoor - One of the best experts on this subject based on the ideXlab platform.
-
Naturally occurring organic acids for organocatalytic Synthesis of Pyrroles via Paal–Knorr reaction
Research on Chemical Intermediates, 2020Co-Authors: Farshid Mohsenzadeh, Kioumars Aghapoor, Hossein Reza Darabi, Mahsa Alivand, Yadollah BalavarAbstract:In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr Pyrrole Synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60 °C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the Synthesis of Pyrrole scaffolds. Graphic abstract
-
Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr Pyrrole Synthesis: a safe, expeditious, and sustainable protocol
Research on Chemical Intermediates, 2018Co-Authors: Kioumars Aghapoor, Farshid Mohsenzadeh, Hossein Reza Darabi, Saeed RastgarAbstract:Among various alkali (Na, K) and alkaline-earth (Ca, Mg, Sr, Ba) chlorides, calcium(II) chloride was found to be a cost-effective Lewis acid catalyst for solvent-free Synthesis of Pyrroles from primary aromatic and aliphatic amines under open-vessel focused microwave irradiation. The salient features of this environmentally benign method are high to quantitative conversion, short reaction time, safe and clean reaction profile, possibility of scale-up to multigram quantities, and use of a low-cost, widely available, nontoxic catalyst. Graphical abstract
-
l-Tryptophan-catalyzed Paal–Knorr Pyrrole cyclocondensation: an efficient, clean and recyclable organocatalyst
Research on Chemical Intermediates, 2016Co-Authors: Kioumars Aghapoor, Hani Sayahi, Farshid Mohsenzadeh, Hossein Reza Darabi, Yadollah BalavarAbstract:A simple, clean, and efficient solvent-free protocol is introduced for Paal–Knorr Pyrrole Synthesis catalyzed by l -tryptophan as a thermally resistant, natural primary amino acid. The products were obtained mostly in excellent yields through the reaction of hexane-2,5-dione with aromatic primary amines bearing a variety of substituents. The catalyst could be easily isolated from the reaction mixture and recycled at least six times without significant loss of activity. The procedure has an environmentally benign nature in agreement with the concepts of green chemistry.
-
Catalytic activity of the nanoporous MCM-41 surface for the Paal–Knorr Pyrrole cyclocondensation
Zeitschrift für Naturforschung B, 2015Co-Authors: Kioumars Aghapoor, Khosrow Jadidi, Farshid Mohsenzadeh, Mostafa M Amini, Hossein Reza DarabiAbstract:AbstractThe investigation of different oxide surfaces revealed that nanoporous silica (MCM-41) had the best catalytic activity for Paal–Knorr Pyrrole Synthesis. Despite the same composition, MCM-41 proved to be more effective than SiO2 itself, probably due to a significantly higher surface area of the SiO2 nanopores. The important features of this “clean” solvent-free protocol are the ease of recovery and the reuse of the catalyst for several cycles, operational simplicity, and easy product isolation and purification.
-
Vitamin B_1 as a metal-free organocatalyst for greener Paal–Knorr Pyrrole Synthesis
Environmental Chemistry Letters, 2012Co-Authors: Hossein Reza Darabi, Abbas Darestani Farahani, Kioumars Aghapoor, Farshid MohsenzadehAbstract:This investigation discloses a greener reaction to prepare Pyrrole derivatives. Metal-free catalysts are greener alternatives to existing metal catalysts in synthetic organic chemistry. Indeed, transition metals are often costly and toxic. They may be found as traces in health reaction products such as pharmaceuticals. Alternatively small organic molecules termed “organocatalysts” allow the Synthesis of valuable products without traces of toxic metals. Here, we show for the first time the use of vitamin B_1 as new organocatalyst for the Paal–Knorr Pyrrole Synthesis under ambient conditions. Reaction conditions were optimized for the reaction of hexane-2,5-dione with 4-methoxyaniline. Ethanol was the most effective solvent. The conversion was quantitative using vitamin B_1, by comparison with a low yield of 30 % without catalysis. The best conditions were performed in ethanol with 5 mol % of vitamin B_1 during 1 h. This reaction was tested using various aromatic amines. To conclude the use of vitamin B_1 for the Paal–Knorr Pyrrole, cyclocondensation has mild reaction conditions, is simple to perform, and gives moderate to excellent yields. It is therefore a promising reaction for the preparation of various Pyrrole derivatives.
Yadollah Balavar - One of the best experts on this subject based on the ideXlab platform.
-
Naturally occurring organic acids for organocatalytic Synthesis of Pyrroles via Paal–Knorr reaction
Research on Chemical Intermediates, 2020Co-Authors: Farshid Mohsenzadeh, Kioumars Aghapoor, Hossein Reza Darabi, Mahsa Alivand, Yadollah BalavarAbstract:In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr Pyrrole Synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60 °C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the Synthesis of Pyrrole scaffolds. Graphic abstract
-
l-Tryptophan-catalyzed Paal–Knorr Pyrrole cyclocondensation: an efficient, clean and recyclable organocatalyst
Research on Chemical Intermediates, 2016Co-Authors: Kioumars Aghapoor, Hani Sayahi, Farshid Mohsenzadeh, Hossein Reza Darabi, Yadollah BalavarAbstract:A simple, clean, and efficient solvent-free protocol is introduced for Paal–Knorr Pyrrole Synthesis catalyzed by l -tryptophan as a thermally resistant, natural primary amino acid. The products were obtained mostly in excellent yields through the reaction of hexane-2,5-dione with aromatic primary amines bearing a variety of substituents. The catalyst could be easily isolated from the reaction mixture and recycled at least six times without significant loss of activity. The procedure has an environmentally benign nature in agreement with the concepts of green chemistry.
-
Silica-Supported Bismuth(III) Chloride as a New Recyclable Heterogeneous Catalyst for the Paal—Knorr Pyrrole Synthesis.
ChemInform, 2012Co-Authors: Kioumars Aghapoor, Yadollah Balavar, Leila Ebadi-nia, Farshid Mohsenzadeh, Mina Mohebi Morad, Hossein Reza DarabiAbstract:The catalyst system exhibits a remarkable reusable activity and a higher performance compared to homogeneous BiCl3.
-
Silica-supported bismuth(III) chloride as a new recyclable heterogeneous catalyst for the Paal–Knorr Pyrrole Synthesis
Journal of Organometallic Chemistry, 2012Co-Authors: Kioumars Aghapoor, Yadollah Balavar, Leila Ebadi-nia, Farshid Mohsenzadeh, Mina Mohebi Morad, Hossein Reza DarabiAbstract:Abstract Silica-supported bismuth(III) chloride (BiCl 3 /SiO 2 ) acts as as a highly efficient heterogeneous Lewis acid catalyst for the Paal–Knorr Pyrrole Synthesis in hexane at room temperature. The catalyst exhibited remarkable reusable activity and higher catalytic performance than homogeneous BiCl 3 . A plausible mechanism for the catalytic action of BiCl 3 /SiO 2 has been introduced.
-
Silica-supported antimony(III) chloride as a mild and reusable catalyst for the Paal–Knorr Pyrrole Synthesis
Environmental Chemistry Letters, 2012Co-Authors: Hossein Reza Darabi, Mohammad Reza Poorheravi, Asyeh Mirzaee, Nazafarin Asadollahnejad, Hossein Taherzadeh, Farshid Mohsenzadeh, Kioumars Aghapoor, Yadollah BalavarAbstract:Heterogeneous catalysts are used for control of environmental pollution. Heterogeneous catalysts are easily separated from the reaction mixture, thus allowing their recovery and re-use. There is a need for catalysts that are efficient under mild conditions. Here, we show that silica-supported antimony(III) chloride (SbCl_3/SiO_2) acts as a highly efficient heterogeneous Lewis acid catalyst for the Paal–Knorr Pyrrole Synthesis at room temperature. We found that condensation of hexane-2,5-dione with aromatic and aliphatic primary amines in hexane using SbCl_3/SiO_2 with 7.6 wt% SbCl_3 was the best reaction condition. The silica support facilitated the workup of the reaction mixture and provided a reusable catalyst at least for 7 runs without significant loss in activity. Indeed, the yield was 98% for the first run and 84% for the 7th run. We conclude that low catalyst loading, operational simplicity, practicability and applicability to various substrates make this reaction an interesting alternative to previously applied procedures. From the environmental standpoint, this eco-friendly catalyst is stable, highly active, easy to prepare and handle.
Uredi Dilipkumar - One of the best experts on this subject based on the ideXlab platform.
-
Total Synthesis of a Pyrrole Lactone Alkaloid, Longanlactone.
ChemInform, 2015Co-Authors: Chada Raji Reddy, Motatipally Damoder Reddy, Uredi DilipkumarAbstract:Key reactions in the first asymmetric total assembly of the natural Pyrrole lactone longanlactone (I) are a Barbier propargylation and a Paal—Knorr Pyrrole Synthesis.
-
Total Synthesis of a Pyrrole Lactone Alkaloid, Longanlactone
European Journal of Organic Chemistry, 2014Co-Authors: Chada Raji Reddy, Motatipally Damoder Reddy, Uredi DilipkumarAbstract:The first asymmetric total Synthesis of the natural Pyrrole lactone longanlactone has been achieved. The key reactions, a Barbier propargylation and a Paal–Knorr Pyrrole Synthesis, have provided easy access to the target natural product from L-aspartic acid in six steps and 31 % overall yield. The C-4 epimer of the natural product and propionyllonganlactone have also been prepared by this strategy.
