Wolfgang Rösch

Ungewöhnlich koordinierte Phosphorverbindungen

Abstract The phosphaalkenes are derived from tris(trimethylsilyl)phosphine and acid chlorides, with acylphosphines considered as intermediates of the reaction. Sodium hydroxide-catalysed elimination of hexamethyl disiloxane (120–160°C) at the phosphaalkenes yields the hitherto unknown phosphaalkynes. These are chemically characterised by [3 + 2]-cycloaddition reactions with diazomethane (→1,2,4-diazaphospholes), methyl azide (→ 1,2,3,4-triazapholes) and benzonitriloxide (1,2,4-oxazapholes).

Reaktive π-Komplexe der elektronenreichen Übergangsmetalle. IV: Cyclisierungsreaktionen von t-Butylphosphaacetylen an π-Areneisen-Komplexen

Abstract The reaction of t-butylphosphaacetylene and bis(ethene)(toluene)iron or (toluene)(1-methylnaphthalene)iron yields t-butyl derivatives of three new complexes (toluene)(1,3-diphosphete)iron (4), (1,3-diphospholyl)(1,3-diphosphete)iron (5), and (1,3-diphospholyi)(1,2,4-triphospholyl)iron (6). 4 shows interesting redox properties.

Ungewöhnlich koordinierte Phosphorverbindungen: XXIV. Methylidinphosphan (HCP), ein neuer Cycloadditionspartner für 1,3-Dipole

Abstract Methylidynephosphane ( 2 ) is generated under flash pyrolytic conditions by cleavage of isobutene from the phosphaalkyne ( 1 ) or by elimination of hydrogen chloride from dichloromethylphosphine ( 3 ). It undergoes [3 + 2]-cycloaddition reactions with stable dipoles eq. diazo compounds ( 2 + 4a,b → 5a,b ), methyl azide ( 2 + 7 → 8 ), benzonitriloxide ( 2 + 10 → 12 , 1:2-adduct) and 3-methyl-2,4-diphenyl-1,3-oxazolium-5-olate ( 2 + 13 → 15 ) to give the corresponding phospholes. Silylated phosphaalkene ( 19 ) can be used as a synthetic substitute for 2 : the 5-trimethylsilyl-1 H -1,2,4-diazaphospholes ( 22 ), which result from the reaction of 19 and the diazo compounds 4 with chlorotrimethylsilane elimination, are desilylated to 5 by potassium fluoride in dimethyl formamide.

PHOSPHOR(III)-VERBINDUNGEN UNGEWÖHNLICHER KOORDINATION, 2.1 ADDITION VON TERT-BUTYLLITHIUM AN 2H-1,2,3-DIAZAPHOSPHOLE

Abstract The 2H-1,2,3-diazaphospholes 1a and b undergo 1,2-addition with tert-butyllithium onto the P/C-double bond under the formation of the lithium derivatives 6a and b, which are transformed into 3-tert-butyl-3,4-dihydro-1,2,3-diazaphospholes with formic acid (6 → 7) or tert-butylchloride (6 → 8 → 7). The lithium compound 6b may be methylated, silylated or carboxylated in the 4-position under the formation of trans-substitution products [10a(A). 10b(A) and 11a(A)]. Some 3,4-dihydro-1,2,3-diazaphospholes are oxidized at the phosphorus atom with hydrogen peroxide or oxygen, sulfur and selenium (12a-g). Die 2H-1,2,3-Diazaphosphole 1a und b gehen mit tert-Butyllithium 1,2-Addition an die P/C-Doppelbindung unter Bildung der Lithiumderivate 6a und b ein, die mit Ameisensaure (6 → 7) oder tert-Butylchlorid (6 → 8 → 7) in 3-tert-Butyl-3,4-dihydro-1,2,3-diazaphosphole umgewandelt werden konnen. Die Lithiumverbindung 6b last sich in 4-Position methylieren, silylieren und carboxylieren, wobei trans-Substitutions...

Phosphorverbindungen ungewöhnlicher Koordination, 5 [3+2]- sowie [4+2]-Cycloadditionsreaktionen an ein kinetisch stabilisiertes Phosphaalken/ Phosphorus Compounds with Unusual Coordination, 5 [3+2]- as well as [4+2]-Cycloaddition Reactions to a Kinetically Stabilized Phosphaalkene

Abstract Aliphatic diazo compounds display different reactivity towards the phosphaalkene 9: diazomethane, diazoethane and terf-butyl diazoacetate (10a-c) formally react with Si/P-insertion to give the hitherto unknown phosphaalkenes 12a-c. In contrast, 1-diazo-2.2-dim ethylpropane (10d) and diazotrimethylsilylmethane (10e) lead to the 1.2.4-diazaphospholes 15 and 17, respectively, if the primary products (11d , 14) are treated with sodium hydroxide in tetrahydrofuran. T he reaction of the nitrile oxides 18a-c with 9 yields the 1.2.4-oxazaphospholes 20a-c; the [3+2] cycloadducts 19a-c are assumed to occur as intermediates, which eliminate hexamethylsiloxane either spontaneously (19a, b) or with OH- -catalysis. Azide dipoles (21a-c) add to 9 with formation of 4.5-dihydro-1.2.3.4-phospholes (22a-c) which - instead of aromatization by hexamethyldisiloxane elimination - prefer fragmentation to 23 (→25 ) and imidoesters 24a-c; hydrolysis produces the pivaloyl amides 26a-c. The 1:2 reaction between 9 and the o-quinones 31a-d proceeds via [4+2] cycloadducts (32a-d) to produce the phosphoranes 34a-d by a subsequent [4+1] cycloaddition process.

LD3- and λ5-1,3-Diphosphacyclobutadienes by Dimerisation of λ3- and λ5-Phospha-alkynes

Abstract λ3-Phosphaalkynes 1 dimerize in the presence of cyclopentadienylcobaltbis (ethylene) (2) to yield λ3-1,3-diphosphacyclobutadienes, which are stabilized by complex formation (3). An excess of 2, finally, is responsible for the formation of the complex 4.

Notizen: Phosphorverbindungen ungewöhnlicher Koordination, 12. Diels-Alder-Reaktionen mit tBu–C ≡ P – ein ergiebiger Weg zu λ3-Phosphininen/ Phosphorus Compounds with Unusual Coordination, 12. Diels-Alder Reactions with tB u–C≡ P–a Lucrative Access to λ3-Phosphinines

Abstract Diels-Alder reactions of the phosphaalkyne 4 with the cyclic 1,3-dienes 5 generate the adducts 6 which decompose spontaneously under elimination of “X ” to yield the λ3-phosphinines 7. The bicyclic 9 decomposes into 7b on flash pyrolysis