Pub Date : 2008-03-10DOI: 10.2174/1874095200801020001
M. Thimmaiah, R. Luck, Shiyue Fang
Five benzoferrocenyl phosphine ligands with the phosphorus atom attached to the 5-position of the benzofer- rocene and some ligand-Mo(CO)5 complexes were prepared and fully characterized; the structure of one ligand was con- firmed by X-ray crystallography. These ligands were applied in palladium-catalyzed allylic alkylation and Suzuki cou- pling of chlorobenzene with phenylboronic acid. Results were compared with those reported previously using ligands hav- ing the phosphorus atom attached to the 4-position of benzoferrocene. This structural modification resulted in an increase of activity of the ligands in allylic alkylation reaction but a decrease of activity in Suzuki coupling reactions. The underly- ing reasons are analyzed with the help of X-ray single crystal determined structures and CO stretching frequencies in the IR spectra of complexes between the ligands and Mo(CO)5.
制备了5个磷原子连接在苯并呋喃二茂烯5位的二苯并呋喃二茂烯配体和一些配体- mo (CO)5配合物，并对其进行了表征;其中一个配体的结构被x射线晶体学证实。这些配体应用于钯催化的烯丙基烷基化反应和氯苯与苯硼酸的铃木偶联反应。结果与先前报道的将磷原子连接到二茂二苯4位的配体的结果进行了比较。这种结构修饰导致配体在烯丙基烷基化反应中的活性增加，而在铃木偶联反应中的活性降低。利用x射线单晶结构测定和红外光谱中Mo(CO)5与配体之间配合物的CO伸展频率分析了其根本原因。
{"title":"Steric and Electronic Effects of Benzoferrocenyl Phosphine Ligands on Palladium-Catalyzed Allylic Alkylation and Suzuki Coupling Reactions","authors":"M. Thimmaiah, R. Luck, Shiyue Fang","doi":"10.2174/1874095200801020001","DOIUrl":"https://doi.org/10.2174/1874095200801020001","url":null,"abstract":"Five benzoferrocenyl phosphine ligands with the phosphorus atom attached to the 5-position of the benzofer- rocene and some ligand-Mo(CO)5 complexes were prepared and fully characterized; the structure of one ligand was con- firmed by X-ray crystallography. These ligands were applied in palladium-catalyzed allylic alkylation and Suzuki cou- pling of chlorobenzene with phenylboronic acid. Results were compared with those reported previously using ligands hav- ing the phosphorus atom attached to the 4-position of benzoferrocene. This structural modification resulted in an increase of activity of the ligands in allylic alkylation reaction but a decrease of activity in Suzuki coupling reactions. The underly- ing reasons are analyzed with the help of X-ray single crystal determined structures and CO stretching frequencies in the IR spectra of complexes between the ligands and Mo(CO)5.","PeriodicalId":23020,"journal":{"name":"The Open Organic Chemistry Journal","volume":"74 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2008-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90051530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-03-10DOI: 10.2174/1874095200801020010
C. Escolástico, M. Blanco, R. Claramunt, D. Sanz, J. Elguero
The synthesis under MW irradiation without solvent of 19 pyrazoles, of which only 8 were known, is described. They bear C-methyl groups and trityl, diphenylmethyl and benzyl groups at positions 1 and 4 of the pyrazole ring. In the reaction between pyrazole and trityl bromide an unexpected reaction occurred and 4-(9-phenyl-9H-fluoren-9-yl)-1H- pyrazole (7) was isolated.
{"title":"Microwave Synthesis of Arylmethyl Substituted Pyrazoles","authors":"C. Escolástico, M. Blanco, R. Claramunt, D. Sanz, J. Elguero","doi":"10.2174/1874095200801020010","DOIUrl":"https://doi.org/10.2174/1874095200801020010","url":null,"abstract":"The synthesis under MW irradiation without solvent of 19 pyrazoles, of which only 8 were known, is described. They bear C-methyl groups and trityl, diphenylmethyl and benzyl groups at positions 1 and 4 of the pyrazole ring. In the reaction between pyrazole and trityl bromide an unexpected reaction occurred and 4-(9-phenyl-9H-fluoren-9-yl)-1H- pyrazole (7) was isolated.","PeriodicalId":23020,"journal":{"name":"The Open Organic Chemistry Journal","volume":"31 1","pages":"10-16"},"PeriodicalIF":0.0,"publicationDate":"2008-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79060763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-01DOI: 10.2174/1874095200802010107
Sun‐Hee Hwang, M. Blaskovich, H. Kim
A convenient one-pot synthesis of 1,2-amino alcohols from -amino acids with retention of optical purity by use of 1,1’-carbonyldiimidazole and sodium borohydride is described.
以1,1′-羰基二咪唑和硼氢化钠为原料，用一锅法合成了光学纯度保持不变的1,2-氨基醇。
{"title":"A convenient reduction of α-amino acids to 1,2-amino alcohols with retention of optical purity","authors":"Sun‐Hee Hwang, M. Blaskovich, H. Kim","doi":"10.2174/1874095200802010107","DOIUrl":"https://doi.org/10.2174/1874095200802010107","url":null,"abstract":"A convenient one-pot synthesis of 1,2-amino alcohols from -amino acids with retention of optical purity by use of 1,1’-carbonyldiimidazole and sodium borohydride is described.","PeriodicalId":23020,"journal":{"name":"The Open Organic Chemistry Journal","volume":"4 1","pages":"107-109"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83652752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-10-24DOI: 10.2174/1874095200701010013
A. Balaban, D. Klein, J. Dahl, R. Carlson
Diamond hydrocarbons (or diamondoids) are hydrocarbons that have a carbon skeleton superimposable on the diamond lattice and contain one or more adamantane units. Recently it was found that many higher diamondoids (contain- ing four to eleven adamantane units) are present in petroleum and can be isolated by a series of methods that include HPLC and GC techniques. We develop QSPR equations using molecular descriptors derived from the topology and geo- metry of diamondoids, by means of dualist graphs consisting of vertices placed at the centers of adamantane cells forming the diamondoid, and of edges connecting vertices centered in adamantane cells sharing faces. From distance (or distance- distance) matrices encoding the topology and geometry of diamondoids one can obtain distance-sums, distance-distance sums, or eigenvectors as molecular descriptors characterizing the diamondoids. These descriptors afford satisfactory cor- relations with GC and HPLC retention data, and may also facilitate the identification of diamondoid isomers.
{"title":"Molecular Descriptors for Natural Diamondoid Hydrocarbons and Quantitative Structure-Property Relationships for Their Chromatographic Data","authors":"A. Balaban, D. Klein, J. Dahl, R. Carlson","doi":"10.2174/1874095200701010013","DOIUrl":"https://doi.org/10.2174/1874095200701010013","url":null,"abstract":"Diamond hydrocarbons (or diamondoids) are hydrocarbons that have a carbon skeleton superimposable on the diamond lattice and contain one or more adamantane units. Recently it was found that many higher diamondoids (contain- ing four to eleven adamantane units) are present in petroleum and can be isolated by a series of methods that include HPLC and GC techniques. We develop QSPR equations using molecular descriptors derived from the topology and geo- metry of diamondoids, by means of dualist graphs consisting of vertices placed at the centers of adamantane cells forming the diamondoid, and of edges connecting vertices centered in adamantane cells sharing faces. From distance (or distance- distance) matrices encoding the topology and geometry of diamondoids one can obtain distance-sums, distance-distance sums, or eigenvectors as molecular descriptors characterizing the diamondoids. These descriptors afford satisfactory cor- relations with GC and HPLC retention data, and may also facilitate the identification of diamondoid isomers.","PeriodicalId":23020,"journal":{"name":"The Open Organic Chemistry Journal","volume":"96 1","pages":"13-31"},"PeriodicalIF":0.0,"publicationDate":"2007-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91276026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-09-28DOI: 10.2174/1874095200701010001
Sonia R. Miranda, P. López‐Alvarado, C. Avendaño, J. Menéndez
Several 3,4-disubstituted indole building blocks were synthesized, containing a one-carbon functional group at C-4 and a three-carbon chain bearing at least one functional group. A C-4 functionalized indole derivative was prepared by application of the Leimgruber-Batcho reaction. Several three-carbon chains were subsequently installed at the indole C-3 position. In the first strategy employed, a Mannich reaction was followed by the creation of a C-C bond by phosphine-induced generation of a 3-methyleneindolenine species, which was trapped by diethyl malonate. Alternatively, a Vilsmeier formylation at C-3 was followed by Knoevenagel or Wittig reactions or by treatment with ethyl diazoacetate in the presence of a Lewis acid. Direct introduction of the three-carbon chain at C-3 using a Lewis acid-catalyzed Michael reaction was also achieved. Further functionalization of the benzylic position attached to C-4 by attachment of a nitro group was carried out, but preparation of a tricyclic welwistatin fragment by intramolecular nitroalkane acylation or in- tramolecular Henry reactions was not possible.
{"title":"Convenient Synthesis of Highly Functionalized, 3,4-Disubstituted Indole Building Blocks","authors":"Sonia R. Miranda, P. López‐Alvarado, C. Avendaño, J. Menéndez","doi":"10.2174/1874095200701010001","DOIUrl":"https://doi.org/10.2174/1874095200701010001","url":null,"abstract":"Several 3,4-disubstituted indole building blocks were synthesized, containing a one-carbon functional group at C-4 and a three-carbon chain bearing at least one functional group. A C-4 functionalized indole derivative was prepared by application of the Leimgruber-Batcho reaction. Several three-carbon chains were subsequently installed at the indole C-3 position. In the first strategy employed, a Mannich reaction was followed by the creation of a C-C bond by phosphine-induced generation of a 3-methyleneindolenine species, which was trapped by diethyl malonate. Alternatively, a Vilsmeier formylation at C-3 was followed by Knoevenagel or Wittig reactions or by treatment with ethyl diazoacetate in the presence of a Lewis acid. Direct introduction of the three-carbon chain at C-3 using a Lewis acid-catalyzed Michael reaction was also achieved. Further functionalization of the benzylic position attached to C-4 by attachment of a nitro group was carried out, but preparation of a tricyclic welwistatin fragment by intramolecular nitroalkane acylation or in- tramolecular Henry reactions was not possible.","PeriodicalId":23020,"journal":{"name":"The Open Organic Chemistry Journal","volume":"5 1","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2007-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74961107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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