Phosphaalkine – Synthesen, Reaktionen, Koordinationsverhalten
TL;DR: In this paper, the authors show how PCR-Einheit in Heterocyclen, in Phosphaarene and deren Valenzisomere, in polycyclische Verbindungen, die Verwendung als neue Ligandensysteme in der Komplexchemie and schlieslich die Cyclooligomerisierung with Organometallreagentien belegen dies auf eindrucksvolle Weise.
Abstract: Organophosphorverbindungen werden auf zweierlei Art in der Synthesechemie eingesetzt: Entweder dienen sie als Hilfsreagentien wie etwa bei der Wittig-Reaktion, oder sie werden selbst in die Zielmolekule eingebaut. Gerade das zweite Anwendungsfeld hat sich durch die Herstellung niederkoordinierter Phosphorverbindungen in den letzten Jahren enorm erweitert. Zu den niederkoordinierten Phosphorverbindungen zahlen auch Phosphaalkine, die im Mittelpunkt dieses Beitrags stehen und viel Interesse sowohl bei Organikern als auch bei Anorganikern gefunden haben. Der Einbau der PCR-Einheit in Heterocyclen, in Phosphaarene und deren Valenzisomere sowie in polycyclische Verbindungen, die Verwendung als neue Ligandensysteme in der Komplexchemie und schlieslich die Cyclooligomerisierung mit Organometallreagentien belegen dies auf eindrucksvolle Weise. Phosphaalkine haben bezuglich ihrer Reaktivitat wenig mit Nitrilen gemeinsam, zeigen aber um so mehr Verwandtschaft mit den isoelektronischen Alkinen.
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636 citations
TL;DR: In this article, an overview is given for the period since 1989 describing the reaction of heterobutadienes and other dienophiles such as carbonyls, thiocarbonyls and iminium salts.
Abstract: The hetero Diels-Alder reaction is one of the most important methods for the synthesis of heterocycles. In this article an overview is given for the period since 1989 describing the reaction of heterobutadienes such as oxabutadienes, thiabutadienes, azabutadienes, diaazabutadienes, nitroso-alkenes and nitroalkenes as well as of heterodienophiles such as carbonyls, thiocarbonyls, imines, iminium salts, azo- and nitroso compounds. In addition, several other less common hetero Diels-Alder reactions such as cycloadditions of thiaazabutadienes, oxaazabutadienes, dioxabutadienes, dithiabutadienes, oxathiabutadienes, diazaoxabutadienes as well as the use of N-sulfinyl-phosphaalkynes and other dienophiles are mentioned. A main point of discussion is the stereoselectivity of the reactions and the preparation of enantiopure compounds either using dienes and dienophiles carrying a chiral auxiliary or employing chiral Lewis acids. A point stressed is the synthesis of natural products using hetero Diels-Alder reactions leading to carbohydrates, alkaloids, terpenes, antibiotics, mycotoxins, cytochalasans, antitumor agents and several other classes of natural products.
317 citations
TL;DR: Complexes discussed in this review facilitate the complexation of sensitive ligands, offer new aspects concerning chirality, allow novel reactions, and are beginning to be applied to transition metal catalysis.
Abstract: Bidendate ligands have proven important in a variety of complexes and are invaluable in a number of catalytic processes. While ligands of this type usually have two identical ligand fragments (homobidendate ligands), heterobidendate ligands allow for a differentiation of the ligands and therefore are prone to selective reactions. This is especially interesting in cases where the ligands are rather different from one another. Phosphane and cyclopentadienyl ligands are among the most commonly used in organometallic chemistry, and they are quite different in nature: Whereas a phosphane is electroneutral and often subjected to ligand exchange processes, the cyclopentadienyl ligand is normally considered to be negatively charged and rather tightly bound to a metal. Reviewing the literature in the field of cyclopentadienylmetal complexes bearing pendant phosphorus, arsenic, and sulfur ligands is timely given that the number of publications of relevance to this topic is growing exponentially as can easily be seen from the list of references in this review: the number of references since 1993 clearly exceeds that of all years before. The reason for this development may be that cyclopentadienylmetal complexes bearing pendant phosphorus, arsenic, and sulfur ligands are expected to perform chemistry different from that of usual cyclopentadienyl complexes. Indeed this has often been the case. Complexes discussed in this review facilitate the complexation of sensitive ligands, offer new aspects concerning chirality, allow novel reactions, and are beginning to be applied to transition metal catalysis. It is therefore hoped that this review will contribute to these developments by offering state of the art information for those active in the field and, even more important, for those who join in the future. This review covers the chemistry of cyclopentadienylmetal complexes, in which the cyclopentadienyl ligand bears a sidearm which includes a phosphorus, arsenic, or sulfur ligand. The pendant ligand has to be separated from the cyclopentadienyl part, that is, † Dedicated to Professor Günther Wilke on the occasion of his 75th birthday. * To whom correspondence should be addressed. Fax: +49/(0)511/ 762-4616. E-mail: holger.butenschoen@mbox.oci.uni-hannover.de. Holger Butenschön was born and raised in Hamburg, Germany. After his army service he studied chemistry at the University of Hamburg and obtained his Dr. rer. nat. degree in 1983 with Professor Armin de Meijere as a fellow of the Studienstiftung des Deutschen Volkes. From 1983 to 1984 he spent a postdoctoral year with Professor K. Peter C. Vollhardt at the University of California at Berkeley as a NATO fellow. Having returned to Germany, he joined the Max-Planck-Institut für Kohlenforschung in Mülheim an der Ruhr as a Liebig fellow to do preparative organometallic work in the fields of anellated arenechromium complexes and cyclopentadienyl cobalt complexes with pendant phosphane ligands. After his habilitation in 1991 (University of Hamburg), he became a Heisenberg fellow of the DFG at the University of Wuppertal from 1992 to 1993. Since 1993 he has been a professor of organic chemistry at the University of Hannover. In 1999 he was a foreign visiting professor at Kyushu University in Fukuoka, Japan. Holger Butenschön is the editor of the German translation of Peter Vollhardt’s and Neil Schore’s textbook Organic Chemistry as well as a coauthor of the Memofix OC. He currently serves as the chairman of the Hannover district of the German Chemical Society (GDCh). His spare time is occupied by the female part of his family, his wife Bettina and their four daughters Lisa, Nora, Inga, and Lara. 1527 Chem. Rev. 2000, 100, 1527−1564
248 citations
TL;DR: Recent developments, concepts and perspectives in the field of phosphinines and phosphinine-based ligands and their application as ligands in homogeneous catalytic reactions are focused on.
Abstract: Phosphinines belong to an intriguing class of phosphorus-containing heterocycles with interesting steric, electronic and coordinating properties. This article focuses on recent developments, concepts and perspectives in the field of phosphinines and phosphinine-based ligands and their application as ligands in homogeneous catalytic reactions.
156 citations
TL;DR: In this article, the authors show that the best known nomenclature of DME is a mixture of lithium-dihydrogen-phosphide and methyl-formate.
Abstract: Das aus Lithium-dihydrogenphosphid. DME(1) und Ethylformiat im Molverhaltnis 2 : 1 mit 87 proz. Ausbeute isolierte, flussige Lithium-formylphosphid. DME liegt als Lithoxy-methylidenphosphan. DME (1) mit einem an den Sauerstoff der Carbonylgruppe gebundenen, DME-komplexierten Lithium vor. Nach Rontgenstrukturanalysen an kristallinen Derivaten [5, 6] dimerisieren Verbindungen dieses Typs unter Ausbildung eines viergliedrigen LiOLiO-Ringes; die Auswertung der NMR-Spektren ergibt fur die an der PC-Gruppe E- und Z-konfigurierten Isomeren (δ1H P: 3,87 u. 4,49; 1JHP: 150,8 u. 136,5; δ1H C: 11,4 u. 10,05; 2JHP: 6,1 u. 81,2; 3JHH: 6,6 u. 13,9; δ31P: 38,6 u. 8,8; δ13C = P: 225,0 u. 215,4 ppm; 1JCP: 41,2 u. 65,0 Hz) des in 1,2-Dimethoxyethan gelosten Acylphosphids 1 ein Molverhaltnis von 1,86 : 1.
Lithium-bis(trimethylsilyl)phosphid. 1,6 THF(1) setzt sich in 1,2-Dimethoxyethan mit Dimethylcarbonat im Uberschus nach einem bisher nicht vollig geklarten Mechanismus zu Lithoxy-methylidinphosphan. 2DME (2) um. Die auch aus Lithium-dihydrogenphosphid. DME zugangliche Verbindung 2 kristallisiert monoklin in der Raumgruppe P21/n {a = 880,6(2); b = 1296,6(2); c = 1267,4(2)pm; β = 96,07(2)° bei - 100 ± 3°C; Z = 4}. Nach der Rontgenstrukturanalyse (Rw = 0,052) weist der zu 155,5 pm bestimmte PC-Abstand einen fur die Dreifachbindung typischen Wert auf, wahrend der CO-Abstand mit 119,8 pm gegenuber dem fur eine Einfachbindung gultigen Standard von 139 pm stark verkurzt ist. Mit Winkeln von 178,5° und 170,7° am Kohlenstoff-und Sauerstoffatom ist das P COLi-Fragment erwartungsgemas linear. Charakteristische NMR-Daten sind: δ31P −384,2; δ13C 166,6 ppm; 1JCP 41,5 Hz.
Acyl- and Alkylidenephosphines. XXXIII Lithoxy-methylidenephosphine · DME and -methylidynephosphine · 2DME — Syntheses and Structures
Lithium dihydrogenphosphide · DME(1) and ethyl formate in a molar ratio of 2 : 1 react in 1,2-dimethoxyethane to give liquid lithium formylphosphide · DME in 87% yield. Since lithium complexed by the chelate ligand DME is bound to the oxygen atom of the carbonyl group, the compound has to be considered as lithoxy-methylidenephosphine · DME (1). According to x-ray structure analyses of crystalline derivatives [5, 6], molecules of this type dimerize forming a four membered LiOLiO ring. Characteristic nmr-data show the presence of an E- and Z-isomer (δ1HP: 3.87 and 4.49; 1JHP: 150.8 and 136.5; δ1HC: 11.4 and 10.05; 2JHP: 6.1 and 81.2; 3JHH: 6.6 and 13.9; δ31P: 38.6 and 8.8; δ13CP: 225.0 and 215.4 ppm; 1JCP: 41.2 and 65.0 cps); in 1,2-dimethoxyethane an E : Z ratio of 1.86 : 1 is found.
In a similar reaction of lithium bis (trimethylsilyl)phosphide · 1.6 THF(1) with excess dimethyl carbonate lithoxy-methylidynephosphine · 2DME (2) is formed via an up to now poorly understood mechanism. The compound can also be prepared from lithium dihydrogenphosphide · DME; it crystallizes in the monoclinic space group P21/n {a = 880.6(2); b = 1296.6(2); c = 1267.4(2) pm; β = 96.07(2)° at −100 ± 3°C; Z = 4}. An x-ray structure analysis (Rw = 0.052) gives a PC distance of 155.5 pm which is typical for a triple bond. The CO bond length of 119.8 pm, however, is extremely short compared to the standard value of a single bond (139 pm). Angles of 178.5° and 170.7° at the carbon and oxygen correspond with the expected linear configuration of the PCOLi backbone of the molecule, Characteristic nmr-data are as follow: δ31P-384.2; δ13C 166.6ppm; 1Jcp 41.5 cps.
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References
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TL;DR: The first successful synthesis of mesomeric-stabilized phosphorus-carbon compounds with coordination number 2, seventeen years ago, was followed nine years later by the preparation of the imino-phosphanes whose intensive investigation has continued to the present day as discussed by the authors.
Abstract: Just as the octet rule had prevented the discovery of the inert-gas compounds, the systematic search for phosphorus-carbon- and phosphorus-nitrogen-compounds having (p-p)π-multiple bonds was hindered by the double bond rule. The first successful synthesis of mesomeric-stabilized phosphorus-carbon compounds with coordination number 2, seventeen years ago, was followed nine years later by the preparation of the imino-phosphanes whose intensive investigation has continued to the present day. A dramatic development has now begun in the phospha-alkene and -alkyne fields, and a large variety of preparative methods have been found. Several compounds of this type are amazingly stable, however they do not participate in typical ylide reactions such as the Wittig reaction. In contrast, the PC double bond is more comparable to that of olefins, which has been confirmed by the occurrence of E,Z-isomers and pericyclic reactions of phospha-l,5-hexadienes.
257 citations
229 citations
TL;DR: In this paper, eine sturmische Entwicklung auf dem Gebiet der Phospha-alkene und -alkine is discussed, e.g., eine Verwandtschaft der PC-Doppelbindung zu Olefinen, welche durch das Auftreten von E,Z-Isomeren sowie durch pericyclische Reaktionen an P-1,5-hexadien-Derivaten bestatigt wird.
Abstract: Wie die Oktettregel der Entdeckung der Edelgasverbindungen im Wege stand, so behinderte die Doppelbindungsregel lange Zeit die systematische Suche nach Phosphor-Kohlenstoff- und Phosphor-Stickstoff-Verbindungen mit (p-p)π-Mehrfachbindungen. Auf die erste Synthese mesomeriestabilisierter Kohlenstoffverbindungen von Phosphor mit der Koordinationszahl 2 vor siebzehn Jahren, die neun Jahre spater beschriebene Herstellung von Iminophosphanen, deren Erforschung bis heute andauert, folgt nun eine sturmische Entwicklung auf dem Gebiet der Phospha-alkene und -alkine. Etliche Mitglieder dieser Stoffklassen, fur die ein Bundel von Syntheseverfahren bereitsteht, erweisen sich als erstaunlich stabil. Typische Ylid-Reaktionen, wie die Wittig-Reaktion, gehen die Phospha-alkene nicht ein. Vielmehr zeigt sich eine Verwandtschaft der PC-Doppelbindung zu Olefinen, welche durch das Auftreten von E,Z-Isomeren sowie durch pericyclische Reaktionen an Phospha-1,5-hexadien-Derivaten bestatigt wird.
223 citations