Phosphonates allyl

Allylic phosphonate esters react with imines, in the presence of a palladium catalyst, to give P-lactams. " Alkynyl reagents such as BuC=CO Li react with imines to form P-lactams. 

An efficient one-pot synthesis of mikanecic acid derivatives was accomplished from allylic phosphonates, ClC02Et, and aqueous HCHO (Eq. 12.38).100 The overall process involves a cascade sequence linking together metalation-alkoxycarbonylation, Homer-Wadsworth-Emmons,... 

Ethoxy-l,3,2-oxazaphospholidine 59 was prepared as a single diastereomer from (-)ephedrine (42) and ethyl dichlorophosphite 57. Its Arbusov reaction with allyl bromide gave the corresponding allyl phosphonates 61a,b as a diastereomeric mixture which could be separated by flash column chromatography and crystallization (Scheme 21) [48], On applying a similar protocol, starting from... 

A-trityl-(l/ ,2S)-norephedrine (58), the corresponding allyl phosphonates 62a,b were obtained via the Arbusov rearrangement of 2-ethoxy-1,3,2-oxazaphospholidine 60. The absolute configuration of the major diastereomer, 62a was determined by X-ray as (2S1,45,51 ).The reaction of the major diastereomer of allyl phosphonates 61a and 62a with DBU afforded the corresponding vinylphosphonates 63a,b (Scheme 21) [48], Nucleophilic addition to these resulted in induction of chirality at the [1-position of the stereogenic phosphorus atom in the initially produced diastereomeric phosphonates 64 or 65 (Scheme 21) [48],... 

Arend, G., Schaffner, H., and Schramm, J., Process For The Production of (Meth)allyl Phosphonic Acid Dialkyl Esters, U.S. Patent 4,017,564, 1977. 

Cleavage of the phosphonate allyl esters from Abu[PO(OAl)2]-peptide-resins is accomplished by treatment with Pd(PPh3)4 (50 °C, 5 h)[103l followed by acidolytic deprotection of the Abu[PO(OH)2]-peptide from the resin support. The viability of employing allyl phosphonate protection for phosphopeptide synthesis has been demonstrated by the Fmoc solid-phase synthesis (DIC/HOBt couplings) of several 6-9-mer Abu[PO(OH)2]-containing peptides and has been extended to the synthesis of a 19-mer caldneurin-related Abu[PO(OH)2]-peptide.[104 ... 

The preparation of unsaturated phosphonates and phosphine oxides represents another class of reagents that are extensively used in organic synthesis. For example, allylic phosphonates are commonly employed in the preparation of dienes and polyenes via Horner-Emmons olefmation. Vinyl phosphonates have numerous uses as both synthetic intermediates" and bioactive compounds. 

Type I (fast homodimerization) Terminal olefins, allylsilanes" Terminal olefins, allylsilanes," 1° allylic alcohols, ethers, and esters, " allyl boronate esters, allyl halides, alkyl-substituted allenes Terminal olefms, allyl boronate esters, 1° allylic alcohols, ethers, and esters,styrenes (no large ortho substit.), " " allyl allylsilanes, allyl sulfides, allyl phosphonates, " allyl phosphine oxides, protected allylamines ... 

In a similar double carbonylation process 2-(propargyl)allyl phosphonates were converted into condensed, unsaturated lactones under anhydrous conditions (3.36.),44... 

An alternative allylic coupling has been reported (J. Am. Chem. Soc. 2004,126, 10676 and 11130) by Amir Hoveda of Boston College. Coupling of the allylic phosphonate 8 with diethyl zinc in the presence of an enantiomerically-pure Cu catalyst gives the branched product 9 in 95% . It is striking that the reaction works almost as well with the allylic phosphonate 10. Reaction with diethyl zinc in the presence of the enantiomerically-pure Cu catalyst forms the quaternary center ofl 1 in 91 % . 

Babler and Schlidt [86] described a route to a versatile C15 phosphonate, used for a stereoselective synthesis of all E retinoic acid and p-carotene. Base-catalyzed isomerization of the vinyl-phosphonate afforded the corresponding allyl-phosphonate as the sole product. Homer-Emmons olefination with ethyl 3-methyl-4-oxo-2-butenoate concluded the facile synthesis of all E ethyl retinoate. The C15 phosphonate was synthesized starting from the epoxide of P-ionone. Subsequent isomerization with MgBr2, afforded the C14 aldehyde in 93%... 

Allylic phosphonates (6) were found to give the SN2 product when treated with some nucleophiles in some reactions and the S 2 product in other reactions.9 Some reactions gave a mixture of the. S N2 and A 2 products. No explanation for this unusual behaviour was given. It was suggested that one or all of the nucleophile, remote substituents on the substrate, or conformational equilibrium of the substrates might determine the S 2/S 2 ratio. 

Methyl-3-phosphorylchroman-4-one 1106 is accessible via a tandem allyl-vinyl migration and cyclization reaction of the allylic phosphonate 1105 and ethyl salicylate (Equation 435) <2001SC2613>. 

Alkenyl-3-phosphoryl chromanones and their thio- derivatives (217) have been synthesized from lithiated allyl phosphonates (218) and salicylate. It is... 

Phosphorus Containing Ring Systems. 1-Acyl allyl phosphonates (376) exposed to the action of m-CPBA in the presence of MgS04 are readily cyclized... 

Phosphonates have also been prepared from alcohols and (Ar0)2P(=0)Cl, NEts and a TiCl4 catalyst. ° The reaction of (R0)2P(=0)H and aryl iodides with a Cul catalyst leads to aryl phosphonates. " Polymer-bound phosphonate esters have been used for olefination. Dienes are produced when allylic phosphonate esters react with aldehydes. 

Recently an allylic phosphonate has been shown to react as an allylic phosphonate cation by transformation to a TT-allyl-palladium complex, susceptible to attack by nucleophiles such as stabilized carb-anions (Scheme 34). ... 

A method for the preparation of alkenes has been described by Tunemoto and coworkers, whereby regioselective a-alkylation of y-substituted allyl phosphonates, followed by reduction with LAH, gives the ( )-alkenes (Scheme 14). 

A study has been made of the kinetics of epoxidation of allylphosphinates and of the addition of C-benzoyl-iV-phenylnitrone to vinyl- and allyl-phosphonates. Boron trifluoride stabilizes phosphorus(v) thiocyanates, preventing their isomerization to isothiocyanates. Cleavage of the phosphinothioic methanesulphonic anhydride (97) with aluminium halides yields the phosphinic halide with retained chirality. ... 

Single P C bond cleavage has been described. For example, phosphonium salts 2.56 are reduced to phosphines by LAH in THF under reflux the cleaved bond corresponds to reduction of the most stable carbanion [H2] (Figure 2.28). The P—C bonds of allylic phosphonates 2.57 or phosphonium salts can also be cleaved by... 

For lithiated allylic phosphonates, the nature of the carbon substituent affects the regioselectivity of the initial silylation as well as the reactivity of the resulting silylated anion.Whereas diethyl... 

Al-Badri, H.. About-Jaudet. E., and Collignon, N., Reaction of in situ generated a-silylated allylic phosphonate carbanions with aldehydes. An unexpected cyclization reaction, J. Chem. Soc., Perkin Trans. 1, 931. 1996. 

Epoxidation of allylic phosphonates is achieved wilh success at room temperature witli MeCOjH in Et O, CF3CO3H in CHCI3, MCPBA in ( HT I- or MOO5/HMPA complex in CH2CI2 to give the corresponding 2,3-epoxyalkylphosphonates as a mixture of diastereomers. s- Allylic phosphonates may also be converted into 2,3-epoxyphosphonates via the 1,1,1-trifluorodimethyl-dioxirane-mediated oxidation. Dimethyldioxirane (DMD) in acetone at room temperature or methyl(trifluoromethyl)dioxirane (TED) in CHjClj at low temperature can be used instead of MCPBA. Because the reaction is quantitative, evaporation of acetone and excess of DMD allow the direct isolation of the pure product. 2,i55... 

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