Reactions of lithiated P -diphenyl(alkyl)( N -methoxycarbonyl)phosphazenes with Michael acceptors and aldehydes. Synthesis of 1 H -1,2-azaphosphinin-6-ones, β-hydroxy( N -methoxycarbonyl)phosphazenes and 5,6-dihydro-1,3,4-oxazaphosphinin-2-ones

Synthesis of Pentacoordinated Spiro[4.4]phosphoranes by Reaction of Cyclic Phosphazenyl Anions with Epoxides: Study of their P-Remote Functionalization and Hydrolysis

“…Remote functionalization with respect to the phosphorus atom and hydrolysis involving P-C aryl bond-breaking are reported for the first time in this family of phosphoranes. 32 and 14e 32 used in this study were prepared according to methods reported in the literature via the Staudinger reaction 33 of ethyldiphenylphosphane with N-methoxycarbonyl azide (method A, 14a) or C  deprotonation of an alkyl-P,P-diphenyl(N-methoxycarbonyl)phosphazene with n-BuLi and subsequent addition of the appropriate alkyl halide (method B, 14b,d,e) (Scheme 4). The 2-methylallyl derivative 14c was synthesized in a one-pot process by trapping lithium diphenylphosphide (obtained through reductive lithiation of triphenylphosphane in THF) 34 with 3-bromo-2-methylprop-1-ene followed by in situ Staudinger reaction with N 3 CO 2 Me (method C).…”

Spiro[1,2]oxaphosphetanes of Nonstabilized and Semistabilized Phosphorus Ylide Derivatives: Synthesis and Kinetic and Computational Study of Their Thermolysis

“…For column chromatography, silica gel 60 (40−63 μm) from Scharlau was used. Phosphazenes 7a, 42 7b, 42 7d, 43 and 7g 43 (precursor of 7f) used in this study were prepared according to methods described in the literature. The synthesis of spiro [1,2]-oxaphosphetanes 9c, 23 9d, 25 9e, 25 9j, 25 45 Z-10e, 19,46 10d (=10p), 23,47 E-10e, 19,48 10j, 49 10k, 50 10l, 51 Z-10n, 48 10o, 52 and 11 19 have been described previously.…”

The Chemistry of Phosphazenes. Synthetic Applications of Cα-Lithiated Derivatives

“…Then, acidbase equilibration regenerate a metalated phosphazene moiety which undergo an intramolecular olefination reaction with the carbonyl group of the azaphosphol ring yielding a bicyclic azaphosphole and N -p h e n y l ( d i p h e n y l ) phosphinamide (96) [93]. The initial steps of the sequence of transformations leading to (100) are similar to those proposed for the synthesis of (92). An indirect support for the first step of this mechanism was provided by the reaction of (74a) with methyl phenylpropiolate and methyl cinnamate.…”

“…Finally, aqueous workup would produce the hydrolysis of the P=N linkage affording the cyclopentenone (92) after a 1,3-proton shift. A new acid-base equilibrium would afford an alcoholate anion that would produce a bicyclic intermediate by intramolecular addition to the carbonyl ester in a 1,5 position, which is finally hydrolyzed to yield the lactone (100). Under the same conditions used for DMAD only the products of regioselective C-acylation (97) and (98) The synthesis of (92)-(95) was unique for two reasons: it represented the first example of a α-lithium phosphazene acting as a bidentate nucleophile, and it was the first time that an olefination reaction mediated by a metalated phosphazene was proposed.…”

“…Dimethyl maleate and butylidenmalonate also gave [1,4] adducts (108) and (109), respectively, upon reaction with lithiated (106a) [100] (eq. 2, Scheme 24).…”