Organophosphorus Chemistry 2018

Organophosphorus chemistry is an important discipline within organic chemistry. Phosphorus compounds, such as phosphines, trialkyl phosphites, phosphine oxides (chalcogenides), phosphonates, phosphinates and >P(O)H species, etc., may be important starting materials or intermediates in syntheses. Let us mention the Wittig reaction and the related transformations, the Arbuzov- and the Pudovik reactions, the Kabachnik–Fields condensation, the Hirao reaction, the Mitsunobu reaction, etc. Other reactions, e.g., homogeneous catalytic transformations or C-C coupling reactions involve P-ligands in transition metal (Pt, Pd, etc.) complex catalysts. The synthesis of chiral organophosphorus compounds means a continuous challenge. Methods have been elaborated for the resolution of tertiary phosphine oxides and for stereoselective organophosphorus transformations. P-heterocyclic compounds, including aromatic and bridged derivatives, P-functionalized macrocycles, dendrimers and low coordinated P-fragments, are also of interest. An important segment of organophosphorus chemistry is the pool of biologically-active compounds that are searched and used as drugs, or as plant-protecting agents. The natural analogue of P-compounds may also be mentioned. Many new phosphine oxides, phosphinates, phosphonates and phosphoric esters have been described, which may find application on a broad scale. Phase transfer catalysis, ionic liquids and detergents also have connections to phosphorus chemistry. Green chemical aspects of organophosphorus chemistry (e.g., microwave-assisted syntheses, solvent-free accomplishments, optimizations, and atom-efficient syntheses) represent a dynamically developing field. Last, but not least, theoretical approaches and computational chemistry are also a strong sub-discipline within organophosphorus chemistry

Editorial for the 100+75 Anniversary Issue of Periodica Polytechnica Chemical Engineering

Editorial for the 100+75 Anniversary Issue of Periodica Polytechnica Chemical Engineerin

Új α-hidroxi-biszfoszfonát származékok előállításának tanulmányozása Al2O3 felületén: The synthesis of new α-hydroxy bisphosphonate derivatives on alumina

The α-hydroxy phosphonates and their derivatives are of importance due to their biologically activity. The molecules are enzyme inhibitors. Preparative methods for α-hydroxy phosphonates are mostly based on the Pudovik reaction, which is the addition of dialkyl phosphite to the corresponding carbonyl compound. There are many examples in the literature for the synthesis of α-hydroxy phosphonates, most of them use different catalysts and solvents. Our research group studied the preparation of α-hydroxy phosphonates under microwave conditions without the use of any solvent. In view of the protection of the environment, as well as the efficient production, an attempt was made to prepare α-hydroxy phosphonate derivatives on the surface of alumina. Diethyl-(2-oxopropyl)phosphonate was selected as the model compound and reacted with five different dialkyl phosphites and diphenyl phosphine oxide. We optimized the conditions of the solid phase to the carbonyl compound. The conclusion is that the acidic surface Al2O3 and a sufficient amount of KF is needed to prepare α-hydroxy phosphonate derivatives in good conversions and in suitable yield. Furthermore, we have to note that the α-hydroxy phosphonate derivatives have interesting NMR properties. Kivonat Az α-hidroxifoszfonátok és származékaik jelentősége biológiai aktivitásukban rejlik. Ezeket a vegyületeket elsősorban enzim-inhibitorként tartják számon. A legáltalánosabbnak mondható módszer α-hidroxifoszfonátok szintézisére a Pudovik-reakció, ahol a dialkil-foszfit addícionálódik az oxovegyületre. Az irodalomban számos példát találunk az α-hidroxifoszfonátok előállítására, mely eljárások többsége a környezetet terheli katalizátorok és oldószerek alkalmazásával. Kutatócsoportunkban széles körben tanulmányozták különböző α-hidroxifoszfonát származékok előállítását környezetbarát módon, mikrohullámú körülmények között, oldószer felhasználása nélkül. A környezet kímélését, valamint a hatékony előállítást szem előtt tartva kísérletet tettünk α-hidroxi-biszfoszfonát származékok előállítására alumínium-oxid felületén. Modellvegyületként a dietil-(2-oxopropil)foszfonátot választottuk, és öt különböző dialkil-foszfittal, valamint difenilfoszfin-oxiddal reagáltattuk. Optimalizáltuk a szilárd fázisban megvalósított karbonil csoportra törénő addíciót, melynek során arra az erdményre jutottunk, hogy savas felületű Al2O3 és megfelelő mennyiségű KF jelenlétében lehet hatékonyan előállítani a kívánt α-hidroxi-biszfoszfonát származékokat, melyek érdekes NMR tulajdonságokkal rendelkeznek

Sugar-based Crown Ethers in Enantioselective Syntheses

A number of chiral macrocyclic compounds have been prepared that contain a monosaccharide-derived sub-unit. These sugar-based crown ethers were used as chiral phase transfer catalysts in a few asymmetric reactions. A few of them proved to be effective catalysts in Michael additions, a Darzens condensation and an epoxidation of α,β-enones. It was found that the type of the monosaccharide, the substituents on the sugar unit and on the nitrogen atom of the macroring have a significant influence on both the yield and the enantioselectivity

Solid-liquid phase C-alkylation of active methylene containing compounds under microwave conditions

The solid–liquid phase C-alkylation of active methylene containing compounds with C=O or P=O functions under phase transfer catalysis or microwave conditions has been summarized in this minireview. The mono- and dialkylation of the methylene containing derivatives was investigated under microwave (MW) conditions. It was found that in many cases, there was no need to use phase transfer catalyst under MW conditions. Moreover, most of the reactions were carried out without any solvent. These results mean a serious green chemical advantage. © 2015 by the authors; licensee MDPI, Basel, Switzerland

Aril-halogenidek reaktivitása a palládium-acetát által katalizált P–C kapcsolási reakciókban: Reactivity of the aryl halides in the palladium-acetate catalyzed P–C coupling reaction

Hirao and co-workers described the first P–C coupling reaction between vinyl- or aryl halides and dialkyl phosphites in the presence of Pd(PPh3)4 as the catalyst in 1980. Due to the high cost and sensitivity of Pd(PPh3)4, the use of various Pd salts (eg. Pd(OAc)2) and added phosphine ligands is a better alternative. Keglevich and his group has been working on the environmentally friendly development of these types of reactions for years. They found that under MW conditions there is no need for expensive P-ligands, if the P-reagent is used in an excess. In our work we studied the coupling reaction of various aryl halides and >P(O)H-reagents. The order of reactivity iodobenzene>bromobenzene>chlorobenzene was confirmed, the coupling of Ph2P(O)H and bromobenzene, which is less reactive than iodobenzene, was optimized by KI additive, so the coupling could be carried out already at 100 °C. An induction period took place at 120 °C. 1.15 equiv. of Ph2P(O)H and 1-bromo-3-chlorobenzene resulted only the chloro-substitued product, in the case of 1,3- and 1,4-dibromobenzene, both the mono- and the biphosphorylated products were formed. To replace both bromine the use of 2.15 equiv. of Ph2P(O)H is required. Kivonat A P–C kötés kialakítására alkalmas keresztkapcsolási módszert Hirao kutatócsoportja dolgozta ki 1980-ban vinil- és aril-halogenidek dialkil-foszfitokkal tölténő kapcsolására Pd(PPh3)4 katalizátor jelenlétében. A katalizátor magas ára és annak érzékenysége miatt később különféle Pd-sókat (pl: Pd(OAc)2,) és foszfin-ligandumokat alkalmaztak.  Kutatócsoportunk évek óta foglalkozik ezen reakciók környezetbaráttabbá tételével, amely során olyan kapcsolási módszert dolgoztak ki, mellyel MW körülmények között a foszforreagens feleslegben történő alkalmazásával elkerülhető a szokásos foszfin-ligandumok használata. Munkánk során aril-halogenidek és >P(O)H-reagensek Pd(OAc)2 által katalizált kapcsolását tanulmányoztuk. Megerősítettük a jódbenzol>brómbenzol>klórbenzol reakcióképességi sorrendet, a jódbenzolhoz képest kevésbé reaktív brómbenzol Ph2P(O)H-al végbemenő foszforilezését KI adalék hozzáadásával optimalizáltuk, így a reakció már 100 °C-on lejátszódott. 120 °C-on egy ún. indukciós periódus jelenlétét figyeltük meg. 1,15 ekv. Ph2P(O)H 1-bróm-3-klórbenzollal végbemenő arilezése során szelektíven a klórszubsztituált termék, míg 1,3- és 1,4-dibrómbenzol esetében mono- és biszfoszforilezett termékek képződtek. Mindkét brómatom helyettesítésére 2,15 ekv. Ph2P(O)H bemérése volt szükséges

Continuous Flow Esterification of a H-Phosphinic Acid, and Transesterification of H-Phosphinates and H-Phosphonates under Microwave Conditions

The microwave (MW)-assisted direct esterification of phenyl-H-phosphinic acid, transesterification of the alkyl phenyl-H-phosphinates so obtained, and the similar reaction of dibenzyl phosphite (DBP) were investigated in detail, and the batch accomplishments were translated into a continuous flow operation that, after optimization of the parameters, such as temperature and flow rate, proved to be more productive. Alcoholysis of DBP is a two-step process involving an intermediate phosphite with two di�erent alkoxy groups. The latter species are of synthetic interest, as precursors for optically active reagents

Dichloridobis(2-methoxy­dibenzo[c,e][1,2]oxaphospho­rine-κP)platinum(II) trichloro­methane solvate

The title compound, [PtCl2(C13H11O2P)2]·CHCl3, has a rare PtCl2 bridging of two dibenzooxaphospho­rine ligands through the metal atom. The PtII ion is in a slightly distorted square-planar environment. The trichloro­methane solvent mol­ecule shows rotational disorder (major occupancy is 0.75) and is placed near to the inversion centre at (1/2, 1/2, 0) in channels parallel to the a axis. The solvent mol­ecule is linked to the complex mol­ecule via inter­molecular bifurcated C—H⋯Cl and C—H⋯O hydrogen bonds. The crystal structure is further stabilized by π–π inter­actions involving the benzene rings, with a centroid–centroid distance of 3.658 (8) Å