By Addition of P-H to Unsaturated Compounds

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds, The first simple benzophosphepin (34) has been prepared by the base-catalysed addition of phenylphosphine to 1,2-diethynylbenzene. Two patents have appeared describing procedures for the synthesis of tris(2-cyanoethyl)phosphine by addition of phosphine to acrylonitrile in ethanol, in the presence of a tertiary (hydroxyalkyl)phosphine and a transition metal. The addition of diphenyl- 

Baudler, G. Reuschenbach, J. Heilman, and J. Hahn, Z. Anorg. Allg. Chem., 1983, 499, 89. 

-induced addition of secondary phosphines to chlorovinylsilanes and allyl(chloro)silanes leads to the silylphosphines (36). A similar addition to vinyl-substituted heterocyclic silanes has given compounds such as (37).  

The addition of secondary phosphines to acrylic acid systems in the presence of acid, followed by treatment with alkali, leads to the phosphinocarboxylates (41). Addition of P-H to carbonyl groups has been employed in the synthesis of the heterocyclic system (42), and to C=N units in the synthesis of the form-amidinophosphines (43). The reaction of phenyl(trimethylsilyl)phosphine to 

By Addition o/P—H to Unsaturated Compounds. There has been a marked reduction in the number of papers concerned with this route in the past year, but nevertheless a number of interesting studies have been reported. Thus, for example, the primary phosphine (21) undergoes free-radical-induced intramolecular cyclization to form the bicyclic phosphine l-phosphabicyclo[3,3,l]nonane (22).  

Issleib and W. Bottcher, Synth. React. Inorg. Metal-Org. Chem., 1976, 6, 179. K. Issleib and P. Thorausch, Phosphorus and Sulphur, 1977, 3, 203. 

The addition of secondary phosphines to vinylaminophosphines, e.g. (23), occurs under both free-radicaP and base-catalysed conditions to form, e.g., (24) or (25). Similar addition of primary phosphines to (23) occurs to form either polymers, e.g. (26), or diphosphacyclohexanes, e.g. (27), depending on the mode of initiation. 

Phosphine and primary phosphines add to vinyl acetate to form (2-acetoxyethyl)-phosphines, e.g. (28), which can be hydrolysed to form (2-hydroxyethyl)phosphines, e.g. (29). The addition of phenylacetylene to phenylphosphine that is co-ordinated to a dicarbonylcyclopentadienylmanganese unit occurs stereospecifically, with the formation of (co-ordinated) phenylbis( ra 5 -/ -styryl)phosphine (30).  

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Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. -Mechanistic aspects of the addition of P-H bonds to alkenes and alkynes have been reconsidered in the light of new activation methods. In the case of additions of diphenylphosphine, radical and ionic routes are indistinguishable, a duality of mechanism being apparent, the coexistence of the two routes bringing about a competition which depends on conditions. The additions of phosphine to simple alkenes, and bicyclic secondary phosphines, e.g., 9-... 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. Base-catalysed addition of diphenylphosphine to phosphazenes derived from diphenylvinylphosphine is the key step in a new route to monophosphazenes (103) of diphosphinoethanes. Base-catalysed additions of primary or secondary phosphines to methyl 1-cyclohexenecarboxylate provide a route to function-... 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. - The second part of a review of P-H addition to carbon-carbon multiple bonds has appeared.A range of heterogeneous catalysts has been developed for the addition of phosphine to alkenes. Radical-induced addition of bis(phenylphosphino)methane to vinylphosphines is the key step in the synthesis of the tetra(tertiary phosphines),(38) each of which exists in meso- and... 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. -This route has not received much attention over the past year. A stereoselective synthesis of tris(Z-styryl)phosphine is offered by the addition of phosphine to phenylacetylene in a superbasic system (HMPA-H20-K0H)." In a similar vein, the reaction of phosphine with styrene and a-methylstyrene in a superbasic medium (DMSO-KOH) provides a route to the primary phosphines, (2-phenylethyl)phosphine and (2-methyl-2-phenylethyl)phosphine, respectively. 7 Transition metal phosphine complexes have been shown to catalyse the a-hydroxylation, P-cyanoethylation, and P-alkoxycarbonylethylation of phosphine. 71 Addition of primary phosphines to acrylic esters has been used for the synthesis of the phosphines (80).7 A similar addition of diphenylphosphine to acrylic esters and amides has given a series of hydrophilic phosphines (81). 72 The bis(phosphorinanyl)ethane (82) is formed in the photochemical addition of l,2-bis(phosphino)ethane to 1,4-pentadiene. ... 

By the addition of P-H to unsaturated compounds. This route has continued to find application, with a slight increase in the number of papers published over the past year. An improved procedure has been reported for the synthesis of the phosphatrioxane system (60) by the direct addition of phosphine (PH3) under atmospheric pressure to an acidified aqueous... 

The Michael addition of nitroalkanes to a,P-unsaturated ketones followed by the Nef reaction has been extensively used as a method for the conjugated addition of acyl anions to enones (see Section 6.1, Nef Reaction). This strategy is one of the best methods for the preparation of 1,4-dicarbonyl compounds.156a h Various natural products have been prepared via this route.157 For example, r/.v-jasmone is prepared from readily available materials, as shown in Scheme 4.19.156f... 

Lowe H, Hessel V, Hubbard S, Lob P (2006) Addition of secondary amines to a, 3-unsaturated carbonyl compounds and nitriles by using microstructured reactors. Org Proc Res Dev 10 1144-1152... 

One of the many important differences between phosphorus and nitrogen chemistry is the relative strengths of their bonds to hydrogen. The relatively weak P—H bond means that this functionality can be added across a wide variety of unsaturated molecules (alkenes, alkynes, carbonyls) and hence this represents an excellent method for preparing tertiary phosphines. The addition of P 11 compounds to C=0 and C=N has been described in detail by Gilheany and Mitchell.2 The reaction can be catalyzed by base (potassium hydroxide, butyllithium), acid (HC1, carboxylic acids, sulfonic acids, boron trifluoride), free radical (uv, organic peroxides, AIBN) or metal (simple metal salts, late transition-metal complexes). In some circumstances no catalyst is required at all for P 11 additions to proceed.60... 

The exocyclic a,P-unsaturated ketones la-h used for the preparation of dibromides 2a-h were E isomers synthesized by known procedures (refs. 7,8). Previously we reported the synthesis of some dibromides (2a,d,g) used here as starting materials, by the bromine addition of the appropriate a,P-unsaturated ketones (la,d,g) (ref. 6). In the case of our present study, compounds lb,c,e,f,h were allowed to react with a small excess of bromine in carbon tetrachloride solution at room temperature for approx. 20 min. to afford the dibromides 2b,c,e,f,h (Eqn. 1) (Table 1). 

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