- Reactions of phosphonates with organohaloboranes: New route to molecular borophosphonates
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Phosphonates RPO(OR′)2 (R = Me, R′ = Et (1); R = CH2Ph, R′ = Et (2); R = CH double bond CH2, R′ = Et (3); R = CH2-CH double bond CH2, R′ = Me (4); R = CH2N3, R′ = Et (5)) react with CyBCl2 (6; Cy = C6H11) in a 1:1 molar ratio in toluene at -30 °C to form the primary adducts CyBCl2·O double bond PR(OR′)2 (7-11). These products undergo a thermally induced bis-chlorodealkylation with the formation of mixtures of oligomers [-O-PR(O-)-O-BCy(O-)]n (22-26) having isovalent P-O-B groupings. Under electron impact mass spectral conditions, the ions [RPO3BCy]4-Cy, which may be attributed to tetramers [RPO3BCy]4 (22′-26′), are detected. Compounds 22′-26′ presumably possess a central cubic M4O12P4 framework that is analogous to those found in alumino- and gallophosphate materials. NMR monitoring shows that [CyBCl(μ2-O)2PR(OR′)]2 (12-16) are formed as intermediates in these reactions. These unstable dimers 12-16 possess a cyclic core analogous to the single-four-ring (4R) secondary building units (SBUs) found in zeolites and phosphate molecular sieves. Hydrolysis of 12-16 and 22-26 with methanol at 30 °C gave respectively RPO(OH)(OR′) (17-21) and RPO(OH)2 (27-31). NMR monitoring reveals that the cyclic dimer [Me2B(μ2-O)2P(CH2Ph)(OEt)]2 (35a) is the primary adduct in the reaction of PhCH2PO(OEt)2 (2) with Me2BBr (34). Heating or prolonged storage at room temperature leads to a mixture of 35a, cyclic borophosphonate Me2BC(μ2-O)2P(CH2Ph)(OEt) (35b), and the mixed anhydride of benzylphosphonic acid and dimethylborinic acid (35c).
- Mortier, Jacques
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p. 4266 - 4275
(2008/10/08)
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- Preparation of dialkyl allylphosphonic acid diesters
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An improved process for the production of allylphosphonic acid dialkyl esters in high yield and selectivity by the gradual addition of trialkyl phosphite to react with the appropriate allyl halide in the presence of a divalent nickel catalyst and, optionally, a polymerization inhibiting compound, e.g. hydroquinone.
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- Palladium-catalyzed preparation of dialkyl allylphosphonates. A new preparation of diethyl 2-oxoethylphosphonate
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Palladium-catalyzed Michaelis-Arbuzov reaction of allyl acetates with trialkyl phosphites affords dialkyl allylphosphonates. Diethyl 2-oxoethylphosphonate is efficiently prepared by ozonization of diethyl allylphosphonate.
- Malet,Moreno-Manas,Pleixats
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p. 2219 - 2228
(2007/10/02)
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