220548-70-9Relevant academic research and scientific papers
Chemistry of 2H-azaphosphirene complexes, 16. - Syntheses, structures, and reactions of C-methoxycarbonyl-functionalized small- and medium-sized P- heterocycle complexes
Streubel,Wilkens,Rohde,Ostrowski,Jeske,Ruthe,Jones
, p. 1567 - 1579 (2007/10/03)
Thermal ring-opening of [{2-bis(trimethylsilyl)methyl-3-phenyl-2H- azaphosphirene-κP}pentacarbonyltungsten(0)] (8a) in the presence of dimethyl acetylenedicarboxylate (DMAD) led to the 2,3-bifunctionalized 1H- phosphirene complex 9a and the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10a, the latter as a by-product. If a small amount of benzonitrile was added, complex 10a was obtained as the main product, along with a small amount of the decomplexed 2H-1,2-azaphosphole 11, which could not be isolated. Reaction of complex 10a with elemental sulfur furnished the corresponding P(v) sulfide 13. When the ring-opening of complex 8a was performed in the presence of two equivalents of DMAD and two equivalents of dimethyl cyanamide, we obtained the 4-dimethylamino-substituted 2H-1,2- azaphosphole complex 10b, together with the diastereomeric AS-1,3,2- oxazaphospholene complexes 14a,b. On reaction of [{2- pentamethylcyclopentadienyl-3-phenyl-2H-azaphosphirene- κP}pentacarbonyltungsten(0)] (8b) and DMAD in toluene, the corresponding 1H-phosphirene complex 9b was only formed as a transient species and the P- coordinated P,C-cage compound 15 was the final product. Using benzonitrile as solvent, the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10c was obtained, together with the 7-aza-1-phosphanorbornadiene complex 16, the latter through partial decomposition of 10c coupled with rearrangement and a Diels-Alder reaction; the ratio 10c/16 was found to depend strongly on the molar ratio of complex 8b to DMAD. A cycloaddition reaction of the 2,3- bifunctionalized 1H-phosphirene complex 9a with 2,3-dimethylbutadiene furnished the bicyclic phosphirane complex 19, along with a small amount of the noncoordinated bicyclic phosphirane 20. Reaction of complex 9a with diethylamine yielded the phosphirane complex 21 as a 1,2-addition product, the diorganophosphane complex 22 through ring-opening of 9a, and the 3,4- functionalized 1,2-dihydro-1-phosphet-2-one complex 23 through an unprecedented ring-expansion reaction, the products 21, 22, 23 were formed in a ratio of ca 1:1.1. The structures of the 1H-phosphirene complex 9a, the 4- dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, the bicyclic phosphirane complex 19, the phosphirane complex 21, and the 1,2-dihydro-1- phosphet-2-one complex 23 have been determined by single-crystal X-ray diffraction analysis.
