X-Ray Crystallographic Investigations of Some Spiro-Derivatives of Cyclotriphosphazatriene

A cis-directing effect towards diols by an exocyclic P-NHR moiety in cyclotriphosphazenes

“…Although both spiro and ansa products were formed in the reaction of tetraethyleneglycol with a cyclophosphazene containing an exocyclic P-NHR group, N 3 P 3 Cl 4 [NH(CH 2 ) 3 O], (1) [14,15], it was found, somewhat surprisingly, that only one ansa product formed and it had the ansa ring on the same side of the phosphazene ring as the exocyclic NH moiety i.e. cis and not trans to the NH group [16].…”

“…The 31 P NMR spectra of the reaction mixture of the reaction of compound 2 with 2,2-dimethyl-1,3-propanediol also shows that only one ansa product is formed, although in this case there is no X-ray crystallographic evidence to prove unequivocally that the ansa ring in 8a is cis to the NH group of the [NH(CH 2 ) 3 X] moiety. The X-ray crystal structure of compound 1 [14] ( Fig. 4) shows that the mean plane of the spiro [NH(CH 2 ) 3 O] moiety is approximately perpendicular to the plane of the cyclophosphazene ring.…”

“…An unusually sensitive solvent effect in the distribution of regio-and stereoisomers of disubstituted derivatives of N 3 P 3 Cl 6 has also reported [11d]. Steric effects obviously play a part; for example, with the sterically very demanding dibenzylamino groups only the trans-isomer, N 3 P 3 Cl 4 [N(CH 2 Ph) 2 ] 2 , is formed [12,13].Although both spiro and ansa products were formed in the reaction of tetraethyleneglycol with a cyclophosphazene containing an exocyclic P-NHR group, N 3 P 3 Cl 4 [NH(CH 2 ) 3 O], (1) [14,15], it was found, somewhat surprisingly, that only one ansa product formed and it had the ansa ring on the same side of the phosphazene ring as the exocyclic NH moiety i.e. cis and not trans to the NH group [16].…”

Crystallographic Proof of Double Walden Inversion in Nucleophilic Substitution Reactions of Macrocyclic Cyclotriphosphazene Derivatives

“…[11,12] Compound 2 (3.5 g, 10 mmol) and tetraethylene glycol (2.91g, 15 mmol) were dissolved in 650 mL of dry THF in a 1-L, three-necked, round-bottomed flask. The reaction mixture was cooled in an ice-bath and NaH (1.2 g, 30 mmol) in 100 mL of dry THF was quickly added to the stirred solution under argon.…”

“…This was achieved by using the mono-spiro derivative N 3 P 3 Cl 4 [O(CH 2 ) 3 NH] (2; Scheme 1), whose synthesis [11,12] and crystal structure [12] have been reported previously. The spiropropanoxyamino group is approximately perpendicular to the cyclophosphazene ring [12] and, because it is linked by two different groups (O and NH) to the N 3 P 3 ring, a distinction can be be made between the two sides (above and below) of the planar cyclophosphazene ring. Reaction of 2 with the sodium derivative of tetraethylene glycol, NaO(CH 2 CH 2 O) 4 Na, gives 4 ]Cl 2 (3), which is a suitable starting material for further nucleophilic substitution reactions of the two remaining P-Cl bonds in a cis-ansa relationship.…”