Experiments on the generation of 2-coordinate phosphoryl species by fragmentation of 7-phosphanorbornene and 3-phospholene derivatives

Photolysis of 7-(2,4,6-trialkylphenyl-)7-phosphanorbornene 7-oxides in the presence of protic species

“…This is also confirmed by the steric hindrance caused by the ortho alkyl substituent of 2b. These observations are consistent with the mechanism proposed earlier [3] involving a five-coordinate species (6) formed by the attack of the alcohol on the P atom of the phosphanorbornene in the first (ratedetermining) step. This is then followed by the fast decomposition of each intermediate 6 to the respec-tive trivalent P species 3-5 that is in tautomeric equilibrium with products 3-5 (Scheme 2).…”

“…After flash column chromatography, the phosphinic species (3a,b, 4a,b, and 5b) were obtained in 65-72% yield and with a purity of 90-95%. The products (3)(4)(5) were identified by 31 P and 1 H NMR and mass spectral data. The P(O)H moiety in 3-5 was easily recognized from the characteristic 1 J(P,H) couplings of 549-557 Hz.…”

“…ates [1][2][3]. Earlier, the fragmentations were believed to proceed through free two-coordinate intermediates (Y-P‫ס‬O; Y‫ס‬Ph, ArO) [1,2].…”

“…Earlier, the fragmentations were believed to proceed through free two-coordinate intermediates (Y-P‫ס‬O; Y‫ס‬Ph, ArO) [1,2]. Quin et al have proven recently that five-coordinate species formed by the attack of alcohol on the P atom of the phosphanorbornene are the real intermediates of the reactions [3].…”

New 7‐phosphanorbornenes derived from 2‐methyl‐1‐phenyl‐ and 1‐cyclohexyl‐3‐ methyl‐2,5‐dihydro‐1H‐phosphole 1‐oxides

“…Photolysis of the bridged P-heterocycles 4 and 5 in acetonitrile in the presence of methanol led to methyl phenyl-H-phosphinate 15 in good yield that, on the basis of its δ P shift of 27.8 and 1 J PH coupling of 567 Hz, could be well identified [12] (Scheme 5).…”