Anil J. Elias

Ring-closing metathesis reactions of terminal alkene-derived cyclic phosphazenes.

The first examples of ring-closing metathesis (RCM) reactions of a series of terminal alkene-derived cyclic phosphazenes have been carried out. The tetrakis-, hexakis-, and octakis(allyloxy)cyclophosphazenes (NPPh(2))(NP(OCH(2)CH=CH(2))(2))(2) (1), N(3)P(3)(OCH(2)CH=CH(2))(6) (2), and N(4)P(4)(OCH(2)CH=CH(2))(8) (3) and the tetrakis(allyloxy)-S-phenylthionylphosphazene (NS(O)Ph)[NP(OCH(2)CH=CH(2))(2)](2) (4) were prepared by the reactions of CH(2)=CHCH(2)ONa with the cyclophosphazenes (NPPh(2))(NPCl(2))(2), N(3)P(3)Cl(6), and N(4)P(4)Cl(8) and the S-phenylthionylphosphazene (NS(O)Ph)(NPCl(2))(2). The reactions of 1-4 with Grubbs first-generation olefin metathesis catalyst Cl(2)Ru=CHPh(PCy(3))(2) resulted in the selective formation of seven-membered di-, tri-, and tetraspirocyclic phosphazene compounds (NPPh(2))[NP(OCH(2)CH=CHCH(2)O)](2) (5), N(3)P(3)(OCH(2)CH=CHCH(2)O)(3) (6), and N(4)P(4)(OCH(2)CH=CHCH(2)O)(4) (7) and the dispirocyclic S-phenylthionylphosphazene compound (NS(O)Ph)[NP(OCH(2)CH=CHCH(2)O)](2) (8). X-ray structural studies of 5-8 indicated that the double bond of the spiro-substituted cycloalkene units is in the cis orientation in these compounds. In contrast to the reactions of 1-4, RCM reactions of the homoallyloxy-derived cyclophosphazene and thionylphosphazene (NPPh(2))[NP(OCH(2)CH(2)CH=CH(2))(2)](2) (9) and (NS(O)Ph)[NP(OCH(2)CH(2)CH=CH(2))(2)](2) (10) with the same catalyst resulted in the formation of 11-membered diansa compounds NPPh(2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)](2) (11) and (NS(O)Ph)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)](2) (13) and the intermolecular doubly bridged ansa-dibino-ansa compounds 12 and 14. The X-ray structural studies of compounds 11 and 13 indicated that the double bonds of the ansa-substituted cycloalkene units are in the trans orientation in these compounds. The geminal bis(homoallyloxy)tetraphenylcyclotriphosphazene [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CH(2))(2)] (15) upon RCM with Grubbs first- and second-generation catalysts gave the spirocyclic product [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)] (16) along with the geminal dibino-substituted dimeric compound [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)(2)PN][NPPh(2)](2) (17) as the major product. The dibino compound 17, upon reaction with the Grubbs second-generation catalyst, was found to undergo a unique ring-opening metathesis reaction, opening up the bino bridges and partially converting to the spirocyclic compound 16.

Synthesis and reactions of ethynylferrocene-derived fluoro- and chlorocyclotriphosphazenes.

The reactions of lithiated ethynylferrocene, FcC[triple bond]CLi (Fc = ferrocenyl), with fluoro- and chlorocyclotriphosphazenes, N(3)P(3)X(6) (X = F, Cl), resulted in the formation of stable mono-FcC[triple bond]CP(3)N(3)X(5) [X = F (1), Cl (2)] and geminal bis[(FcC[triple bond]C)(2)PN](X(2)PN)(2) [X = F (3), Cl (4)], ethynylferrocene-substituted cyclophosphazenes. The reactions of 1 and 2 with CpCo(COD) were found to differ in the nature of the sandwich compounds (eta(5)-Cp)Co{eta(4)-C(4)[Fc(2)(N(3)P(3)X(5))(2)]} formed. While the fluorophosphazene-derived compound 1 yielded both cis and trans isomers of the cyclobutadiene complexes 5 and 6, the chlorophosphazene-derived compound 2 was found to give only the trans-cyclophosphazene-disubstituted cyclobutadiene compound 7. The reaction of 3 with CpCo(COD) was found to give the compound (eta(5)-Cp)Co{eta(4)-C(4)-1,3-(Fc)(2)-2,4-[NP(C[triple bond]CFc)(NPF(2))(2)](2)} (8) having one of the alkyne units of the cyclophosphazene moiety of 3 remaining unreacted even after reaction with an excess of CpCo(COD). The first click reactions of ethynylferrocene-derived cyclophosphazenes have been carried out by reacting 1 and 4 with benzyl azide, resulting in novel mono- and disubstituted cyclophosphazene-derived 1,2,3-triazoles. The reaction of 1 with benzyl azide yielded two positional isomers of the 1,2,3-triazole, (1-PhCH(2), 4-Fc, 5-P(3)N(3)F(5))C(2)N(3) (9), and (1-PhCH(2), 4-P(3)N(3)F(5), 5-Fc)C(2)N(3) (10), with the latter having a benzyl group in the vicinity of the ferrocene unit as the major product. A similar reaction of 4 with benzyl azide was found to yield five triazole-based products, with two, [(1-PhCH(2)-4-FcC(2)N(3))(C[triple bond]CFc)PN](PNCl(2))(2) (11) and [(1-PhCH(2)-5-Fc-C(2)N(3))(C[triple bond]CFc)PN](PNCl(2))(2) (12), having one unreacted alkyne unit in the molecule. Among the bis-triazole-derived chlorophosphazenes [(1-PhCH(2)-4-Fc-C(2)N(3))(2)PN](PNCl(2))(2) (13), [(1-PhCH(2)-4-Fc-C(2)N(3))(1-PhCH(2)-5-Fc-C(2)N(3))PN](PNCl(2))(2)] (14), and [(1-PhCH(2)-5-Fc-C(2)N(3))(2)PN](PNCl(2))(2) (15), the unsymmetrically disubstituted bis-triazole compound 14 was found to be the major product. The fluorophosphazene-derived triazole 10 was found to readily form a disubstituted square-planar complex trans-[(1-PhCH(2)-4-P(3)N(3)F(5)-5-Fc)C(2)N(3)](2)PdCl(2) (16) with PdCl(2)(PhCN)(2). All of the new ferrocene- and cyclophosphazene-derived compounds except 8 and 12 have also been structurally characterized.

Perfluorinated cyclic phosphazenes

Publisher Summary This chapter discusses properties and reaction chemistry of perfluorinated cyclophosphazenes, with an emphasis on comparing their reactivity with that of the perchlorinated analogs. In contrast to chloro- and bromophosphazenes, for which a variety of synthetic methods have been reported, the only effective way of making fluorophosphazenes is by fluorinating chlorophosphazenes to per-or polyfluorinated derivatives using a variety of fluorinating reagents. Fluorination of chlorophosphazenes, especially the trimeric phosphazene, has been the subject of studies primarily to understand the mechanism and regiospecificity involved in metathetical reactions. The boiling points of the cyclic fluorophosphazenes are similar to those of saturated aliphatic fluorocarbons of comparable molecular weight. Structures of cyclic fluorophosphazenes, especially those of the smaller rings, received increased attention because these data were utilized to support theoretical studies in which participation of phosphorus d orbitals and contraction of d orbitals for effective overlap for π bonding were discussed. Reactions of a variety of monofunctional nucleophiles have been carried out with trimeric perfluorinated phosphazenes.

Cyclic SN compounds and phosphorus reagents—VII. Reactions of S4N4 with tertiary (amino)phosphines: Synthesis and characterization of (R2N)3PN-S3N3 derivatives and their addition products with norbornadiene. X-ray crystal structure of (C5H10N)3PN-S3N3

Abstract The reactions of the tertiary (amino)phosphines (R2N)3P [R2N = C4H8N-, C5H10N-, C6H12N-, OC4H8N-, and CH3NC4H8N-·] with S4N4 are described. The phosphiniminocyclotrithiazenes (R2N)3PN-S3N3 (1–5) are the only heterocyclic products isolated (60–80% yield). Excess (amino)phosphines cleave the heterocycles readily while norbornadiene reacts with them to give rise to the addition products, (R2N)3PN-S3N3·C7H8 (6–9) in small yields. The single crystal X-ray structure of (C5H10N)3PN-S3N3 (triclinic system, space group P1) gave the unit cell dimensions: a = 9.573(5), b = 10.372(6), c = 10.916(6) A, α = 85.46(3), β = 81.13(4), γ = 79.73(4)°, V = 1052.25 A3 and Z = 2. The structure has been compared with that of Ph3PN-S3N3 which is the only other compound of this type (R3PN-S3N3) whose X-ray structure is known.

Synthesis and Selectivity in the Formation of Cyclophosphazene-Derived 1,3-Cyclohexadienes from Reactions of RCpCo(COD) [R = MeOC(O)] with Alkynes and Alkenes

The first examples of mono and bisfluorophosphazene derived [eta (5)-cyclopentadienyl] [eta (4)-1,3-cyclohexadiene] cobalt complexes have been prepared along with the sandwich compound [eta (5)-carbomethoxycyclopentadienyl] [eta (4)-1,3-bis(pentafluorocyclotriphosphazenyl)-2,4-diphenylcyclobutadiene] cobalt and acetylene trimerized products from the reactions of [eta (5)-MeOC(O)C 5H 4]Co[COD], PhCCP 3N 3F 5 and phenylacetylene in the presence or absence of an additional cycloalkene or indene. Formation of these mono and bis fluorophosphazene derived cobalt cyclohexadiene complexes provide experimental evidence for a metallacyclopentadiene pathway for cyclohexadiene formation in CpCo catalyzed reactions. Selectivity is also observed in the formation of bisfluorophosphazene derived cyclohexadienes which stems from the fact that two P 3N 3F 5 units cannot be accommodated on vicinal carbon atoms of a carbacycle or metallacycle. Interestingly, reactions of (beta-phenylethynyl)pentafluorobenzene with [eta (5)-MeOC(O)C 5H 4]Co[COD] in the presence and absence of external cycloalkene under identical reaction conditions yielded only the cis and trans isomers of the metallocene [eta (5)-MeOC(O)C 5H 4]Co[eta (4)-C 4Ph 2(C 6F 5) 2] along with alkyne trimerized product indicating that the selectivity in cyclohexadiene formation is governed more by steric than electronic factors. All the new compounds were characterized by (1)H, (13)C, (31)P, and (19)F NMR as well as mass spectrometry and elemental analysis. Mono and bispentafluorocyclotriphosphazene derived [eta (5)-cyclopentadienyl] [eta (4)-1,3-cyclohexadiene] cobalt complexes and [eta (5)-carbomethoxycyclopentadienyl] [eta (4)-bis(1,3-pentafluorophenyl)-2,4-diphenylcyclobutadiene] cobalt have also been structurally characterized by single crystal X-ray analysis.

Polyfluoroalkoxy and aryloxy cyclic phosphazenes : an alternative synthesis route to substitution reactions using siloxanes in the presence of fluoride ion catalysts

The first detailed investigations on the reactions of polyfluoromono- and dialkoxysilanes with cyclic fluorophosphazenes are carried out and compared with reactions of the nonfluorinated analogues. The method offers an easy and elegant route to the hitherto poorly studied bridged and dangling phosphazene compounds. For the first time a transformation of bridged phosphazene compount to spiro compounds is observed and monitored by 19 F NMR studies. An explanation is offered for the poor yields and inability to isolate bridged derivatives experienced by previous workers

A convenient and high yield synthesis of tertiary (amino) phosphines by transamination route

Abstract Tris (diethylamino)phosphine affords tertiary (amino) phosphines of pyrrolidine, piperidine, hexamethyleneimine, morpholine and N-methylpiperazine in nearly quantitative yields by transamination route - an easy and convenient synthesis occuring under mild conditions.

Cyclic SN compounds and phosphorus reagents part 6. Reactions of S4N4 with symmetrical tertiary phosphines, R3P (R = t-C4H9, c-C6H11, C6H5CH2, p-MeOC6H4 and p-ClC6H4): Isolation and characterization of phosphinimino substituted cyclic sulphur nitrides

Unlike Ph3P, reactions of S4N4 with symmetrical tertiary phosphines, R3P (R = t-butyl, cyclohexyl, benzyl, p-methoxyphenyl and p-chlorophenyl) afford only the corresponding phosphiniminocyclotrisul-phurtrinitrides, R3PNS3N3 (I–V) in moderate to good yields. (p-ClC6H4)3P alone yields the disubstituted S4N4 derivative, 1,5-[(p-ClC6H4)3PN]2S4N4 (VI) in low yield which undergoes a ring contraction in solution. Among the red crystalline compounds I–V, those containing aliphatic substituents on phosphorus (I–III) are less stable both in solid and solution phases than those containing aromatic substituents (IV and V). Various spectroscopic data have been discussed.

Novel ferrocene derived cyclocarbaphosphazenes: synthesis and structure of spiro {Fe(η-C5H5)-[η-C5H4CH2P(S)(CH2O)2PN]}(Me2NCN)2

Abstract The first examples of ferrocene derived cyclocarbaphosphazenes have been synthesized by the reaction of Fe(η-C5H5)-[η-C5H4CH2P(S)(CH2OLi)2] with (RR′NCN)2(Cl2PN) [RR′N=Me2N and PhCH2(Me)N]. The crystal structure of the spirocyclic compound {Fe(η-C5H5)-[η-C5H4CH2P(S)(CH2O)2PN)]}(Me2NCN)2 has been determined and shows an axial orientation of the ferrocenylmethyl group with respect to the six-membered chair form of the spirocycle.

CYCLOCARBOPHOSPHAZENES: SYNTHESES, REACTIONS AND PROPERTIES

Abstract The syntheses, reactions, properties and uses of cyclocarbophosphazenes have been described. The specific synthetic methodologies adopted for the syntheses of the six, eight and twelve membered heterocycles with varying ring substituents from fully halogenated to fully aliphatic or aromatic substituted have been discussed. The different types of reactions of these heterocycles have been classified under nucleophilic substitution, partial ring saturation and ring degradation and polymerization reactions. The physical and spectral properties with emphasis on IR, NMR and X ray structural investigations as well as important applications of these compounds have also been presented.