- Synthesis of electron-rich sterically hindered P1 phosphazene bases by the staudinger reaction
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The synthesis of electron-rich P1 phosphazene bases with a sterically protected basic center by a Staudinger reaction is reported. The initial products of the reaction between peralkylated triaminophosphanes and bulky alkyl azides, phosphazides 1a-f, were isolated in all cases in good to quantitative yield. The structures of 1d and 1e were confirmed by single-crystal X-ray diffraction. Acidic hydrolysis of pyrrolidino-substituted phosphazide (pyrr)3PN3tBu 1d led to the quantitative formation of aminophosphonium salt (pyrr)3PNH2+· BF4- 8, a direct precursor to a Schwesinger's "building block" synthetic unit. Thermally induced denitrogenation of the phosphazides, which is the second step performed in most cases under solvent-free conditions gave P1 phosphazene bases 2a-f in moderate to excellent yields. A "one-pot" two-step synthesis of phosphazene bases from commercially available triaminophosphanes was discovered. Most of the syntheses were performed on a large laboratory scale. The basicities of the newly synthesized bases 2e and 2f were determined. X-ray crystal structures were obtained for base 2e and for protonated species 2d·HBF4, 2e·HBF4, and 2f·HOTs, which provided the crucial geometrical parameters around the basic center. A rationale for the higher basicity of the pyrrolidino- (pyrr)3P=NR than the piperidino- (pip)3P=NR phosphazenes is presented. A Staudinger reaction was successfully used for the synthesis of a number of sterically congested electron-rich P1 phosphazene bases in moderate to quantitative yield. The intermediate phosphazides were isolated and characterized in all cases; their application in the preparation of higher-order phosphazenes is described. Copyright
- Alexandrova, Anastasia V.,Masek, Tomas,Polyakova, Svetlana M.,Cisarova, Ivana,Saame, Jaan,Leito, Ivo,Lyapkalo, Ilya M.
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p. 1811 - 1823
(2013/04/10)
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- Tricyclic phosphorous triamides
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Polycyclic phosphorous triamides of the formula STR1 in which R1 and R2, alike or different, are alkylene of 2 to about 6 carbons; R3 and R4, alike or different, are alkyl of 1 to about 8 carbons, cycloalkyl of 5 to about 8 carbons, or aralkyl where the aryl group is of 6 to about 12 carbons and the alkyl is of 1 to about 8 carbons; or R3 and R4 are joined together to form an alkylene group of 2 to about 6 carbons which may be interrupted by 1. a STR2 group where Q is hydrogen or alkyl of 1 to about 18 carbons, or 2. ONE OR TWO --O-- linkages; There are at least 2 carbons between each two hetero atoms in the outer ring system, and when the triamide is tricyclic, at least one of the chains between the nitrogens linked to phosphorus contains at least three atoms Are useful as flame retardants for cotton.
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- Bicyclic and tricyclic phosphorous triamides
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Polycyclic phosphorous triamides of the formula STR1 in which R1 and R2, alike or different, are alkylene of 2 to 6 carbons; R3 and R4, alike or different, are alkyl of 1 to 8 carbons, cycloalkyl of 5 to 8 carbons, or aralkyl where the aryl group is of 6 to 12 carbons and the alkyl is of 1 to 8 carbons; or R3 and R4 are joined together to form an alkylene group of 2 to 6 carbons which may be interrupted by 1. a STR2 group where Q is hydrogen or alkyl of 1 to 18 carbons, or 2. ONE OR TWO --O-- linkages; there are at least 2 carbons between each two hetero atoms in the outer ring system, and when the triamide is tricyclic, at least one of the chains between the nitrogens linked to phosphorus contains at least three atoms Are useful as flame retardants for cotton.
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