194469-91-5

Upstream product

• 171625-87-9 pentacarbonyl[2-(bis(trimethylsilyl)methyl)-3-phenyl-2H-azaphosphirene-κP]tungsten(0) 
• 100-47-0 benzonitrile 
• 762-42-5 dimethyl acetylenedicarboxylate 

Relevant 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

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.

Synthesis of 2H-1,2-azaphosphole complexes by [3 + 2] cycloaddition of nitrilium phosphane-ylide complexes with various alkynes: Studies of the C-substituent and metal effects on the reaction course

Thermal ring opening of [2-(bis(trimethylsilyl)methyl)-3-phenyl-2H-azaphosphirene-κP]- pentacarbonylchromium(0), -molybdenum(0), or -tungsten(0) (la-c) in the presence of three different alkynes, phenylacetylene, ethyl acetylenecarboxylate (EAC), and dimethyl acetylenedicarboxylate (DMAD) (i-iii), was investigated, using toluene (a) and benzonitrile (b) as solvents, whereby special emphasis was to determine the dependence of the [2 + 1]/[3 + 2] cycloaddition product ratio and the regioselectivity on the electronic properties of the acetylenes and the transiently formed nitrilium phosphane-ylide complexes. It is shown that the stability of the latter clearly depends on the donor abilities of the C-substituent of the C,N,P 1,3-dipole system. In toluene 1H-phosphirene complexes 11a-c are obtained exclusively (ia), whereas when EAC (iia) and DMAD (iiia) were employed as trapping reagents, the metal-dependent formation of either a mixture of 1H-phosphirene and 2H-1,2-azaphosphole complexes (M = Cr, W; iia, 12a,c and 13a,c; iiia, 4a,c and 5c) or a mixture of 1H-phosphirene and a diphosphene complex was observed (M = Mo; iia, 12b and 14; iiia, 4b and 14). Reaction iia yielded 13a,c regioselectively. Exclusively in the case of DMAD (iiia,b), but for all 2H-azaphosphirene complexes 1a-c, the further unidentified byproduct 15 was detected spectroscopically. In benzonitrile the reactions of complexes 1a-c led generally to decreased yields of 1H-phosphirene complexes 11a-c (ib) but not to 2H-1,2-azaphosphole complex formation in the case of ib. In the case of the reactions iib and iiib, significantly changed 1H-phosphirene/2H-1,2-azaphosphole complex ratios are observed in favor of the latter (complexes 13a,c and 5c). Although the regioisomeric complexes 13a,c were formed predominantly, evidence was obtained spectroscopically, at least, for the other regioisomeric tungsten complex 18a. The dependence of the 1H-phosphirene/2H-1,2-azaphosphole complex ratios on the arylnitrile concentration and the electronic influence of the para aryl substituent was demonstrated by an 31P NMR spectroscopic study (iv) for the 2H-azaphosphirene complexes 1c and 16a,b. Further three-component reactions with 2H-azaphosphirene complexes, different nitriles, and DMAD (v), EAC (vi-viii), and phenyl-acetylene (ix) are reported. Thus, thermolysis of complex 1c in acetonitrile or tert-butyl cyanide and with DMAD led to 5-alkyl-substituted 2H-1,2-azaphosphole complexes 17c,d (v), and with acetonitrile and EAC the 2H-1,2-azaphosphole complex 13d was obtained (vi). Thermolysis of 2H-azaphosphirene complexes 1a-c in toluene with EAC as trapping reagent and dimethyl cyanamide (vii) or 1-piperidinonitrile (viii) selectively furnished 2H-1,2-azaphosphole complexes 13e-h and 18b-e, the former being the preferred regioisomers. Using the 2H-azaphosphirene complex 1c, dimethyl cyanamide or 1-piperidinonitrile, and phenylacetylene (ix), the last as solvent and trapping reagent, gave complicated product mixtures. These consist each of three different types of main products, the 2H-1,2-azaphosphole complexes 21a,b and the two acyclic, isomeric complexes 22a,b and 23a,b, resulting from opposite 1,3-additions of the C-H function of phenylacetylene to the 1,3-dipole system of the intermediately formed C-dialkylamino-substituted nitrilium phosphaneylide complexes 10 and 19c; reaction ix shows that stability and reactivity significantly depend on the C-substituent of the C,N,P 1,3-dipole system. The structures of the 2H-1,2-azaphosphole complex 21a and of the [bis(trimethylsilyl)methyl](trimethylsiloxy)phosphane complex 24c were determined by single-crystal X-ray diffraction.

Photochemically generated nitrilium phosphane-ylid tungsten complexes and their reactivity towards alkyne and nitrile derivatives

The photochemically generated nitrilium phosphane-ylid tungsten complex 2 reacts with different activated alkynes, dimethyl acetylenedicarboxylate (DMAD) (i) and ethyl acetylenecarboxylate (ii), and nitriles, ethyl cyanoformate (ECF) (iii) and 1-piperidin

Formation of 2H-1,2-azaphosphole tungsten complexes by tapping reactions of nitrilium phosphane ylide complexes

The novel heterocyclic ligand system in 2 is formed by thermal decomposition of 2H-azaphosphirene tungsten complexes in the presence of dimethylacetylenedicarboxylate (DMAD). The formation of the 2H-1,2-azaphosphole tungsten complexes 2 is interpreted as the reaction of the novel ylidic intermediates 1 with DMAD. The latter are very promising in view of the potential of known nitrile ylides in heterocycle syntheses. Ar = p-MeOC6H4, Ph, p-F3CC6H4.