14303-02-7Relevant articles and documents
Ring-closing metathesis reactions of terminal alkene-derived cyclic phosphazenes
Kumar, Dheeraj,Singh, Nem,Keshav, Karunesh,Elias, Anil J.
experimental part, p. 250 - 260 (2011/03/17)
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(OCH2CH = CH2)2)2 (1), N3P3(OCH2CH = CH2)6 (2), and N4P4(OCH2CH = CH2) 8 (3) and the tetrakis(allyloxy)-S-phenylthionylphosphazene (NS(O)Ph)[NP(OCH2CH = CH2)2]2 (4) were prepared by the reactions of CH2 = CHCH2ONa with the cyclophosphazenes (NPPh2)(NPCl2)2, N 3P3Cl6, and N4P4Cl 8 and the S-phenylthionylphosphazene (NS(O)Ph)(NPCl2) 2. The reactions of 1-4 with Grubbs first-generation olefin metathesis catalyst Cl2Ru = CHPh(PCy3)2 resulted in the selective formation of seven-membered di-, tri-, and tetraspirocyclic phosphazene compounds (NPPh2)[NP(OCH2CH = CHCH2O)]2 (5), N3P3(OCH 2CH = CHCH2O)3 (6), and N4P 4(OCH2CH = CHCH2O)4 (7) and the dispirocyclic S-phenylthionylphosphazene compound (NS(O)Ph)[NP(OCH2CH = CHCH2O)]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 (NPPh2)[NP(OCH2CH2CH = CH2) 2]2 (9) and (NS(O)Ph)[NP(OCH2CH2CH = CH2)2]2 (10) with the same catalyst resulted in the formation of 11-membered diansa compounds NPPh2[NP(OCH 2CH2CH = CHCH2CH2O)]2 (11) and (NS(O)Ph)[NP(OCH2CH2CH = CHCH2CH 2O)]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 [NPPh2] 2[NP(OCH2CH2CH = CH2)2] (15) upon RCM with Grubbs first- and second-generation catalysts gave the spirocyclic product [NPPh2]2[NP(OCH2CH 2CH = CHCH2CH2O)] (16) along with the geminal dibino-substituted dimeric compound [NPPh2]2[NP(OCH 2CH2CH = CHCH2CH2O) 2PN][NPPh2]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.
