Hydrophosphonylation alkenes

Because organophosphorus compounds are important in the chemical industry and in biology, many methods have been developed for their synthesis [1]. This chapter reviews the formation of phosphorus-carbon (P-C) bonds by the metal-catalyzed addition of phosphorus-hydrogen (P-H) bonds to unsaturated substrates, such as alkenes, alkynes, aldehydes, and imines. Section 5.2 covers reactions of P(lll) substrates (hydrophosphination), and Section 5.3 describes P(V) chemistry (hydrophosphorylation, hydrophosphinylation, hydrophosphonylation). Scheme 5-1 shows some examples of these catalytic reactions. 

The hydrophosphonylation (addition of dialkyl phosphonates), hydrophos-phinylation (addition of alkyl alkylphosphinates or alkyl phosphinates) and addition of secondary phosphine oxides to unfunctionalized alkenes and alkynes occur under free radical conditions or with transition metal catalysis.10,39 63 90... 

A Rh catalyst mediated anti-Markovnikov hydrophosphonylation of alkenes in a polymer to give a linear product (Scheme 16). A catalyst formed from Wilkinson s complex and four equiv of dpph was the most active this ligand was suggested to be bidentate, but the active Rh species was not identified [26, 27]. 

Scheme 29 Proposed mechanism for Ti-catalyzed hydrophosphonylation of activated alkenes...

One of the most practical methods for the radical hydrophosphonylation of alkenes uses manganese (II) acetate to promote the addition reaction (Schane 4.75) [129], The chemistry was operationally trivial, and simply adding the reagents to a reaction vessel in air followed by stirring under air at 90 °C afforded fair to excellent yields of the alkylphos-phonates. For terminal alkenes, the reaction selectively formed the anti-Markovnikov... 

The palladium-catalysed hydrophosphonylation of alkenes (320) with acyclic diall l phosphites (i -phosphonates) afforded the corresponding phosphonates (321) in moderate to good yields and with excellent levels of regioselectivity (up to >1 99 ot/p) (Scheme 88)/ °... 

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