88080-20-0Relevant academic research and scientific papers
Epimerization of cyclic vinylphosphirane complexes: The intermediacy of biradicals
Wang, Bing,Lake, Charles H.,Lammertsma, Koop
, p. 1690 - 1695 (2007/10/03)
The phosphinidene complex Ph-P-W(CO)5 reacts with cyclopentadiene, 1,3-cyclohexadiene, 1,3-cycloheptadiene, and 1,3-cyclooctadiene to give in each case isomeric mixtures of syn- and anti-vinylphosphiranes. With longer reaction times and/or higher reaction temperatures, the anti adducts isomerize to the syn adducts. These epimerizations are likely to proceed via biradical intermediates. Only the syn-vinylphosphirane of 1,3-cyclohexadiene undergoes a [1,3]-sigmatropic shift to yield a syn-phopholene. The dichotomy of biradical and concerted mechanisms is discussed in relationship with the analogous mechanism for the vinylcyclopropane → cyclopentene rearrangement.
The carbene-like behavior of terminal phosphinidene complexes toward olefins. A new access to the phosphirane ring
Marinetti, Angela,Mathey, Fran?ois
, p. 456 - 461 (2008/10/08)
In the presence of copper(I) chloride, (7-R-7-phosphanorbornadiene)P-M(CO)5 complexes (M = Cr, W) decompose around 55°C to give the corresponding terminal phosphinidene complexes RP=M(CO)5. These transient phosphinidene complexes react in situ with olefins to give phosphirane complexes. The stereochemistry of the starting olefin is retained in the phosphirane ring, thus suggesting a concerted process. The reaction with 1,3-dienes yields 2-vinylphosphirane complexes that rearrange around 100°C to the corresponding phospholenes. On the contrary, the reaction with α,β-unsaturated ketones gives directly the 1,2-oxaphospholene complexes, but the formation of an intermediate 2-acylphosphirane cannot be excluded. With methyl methacrylate, the 2-(methoxycarbonyl)phosphirane is formed and is apparently stable. With ethyl vinyl ether, the 2-ethoxyphosphirane transiently obtained is so reactive that neutral water cleaves the P-C(OEt) bond of the ring to give a secondary α-phosphinoacetaldehyde that is stabilized as its P-W(CO)5 complex. An excess of vinyl ether also reacts with the 2-ethoxyphosphirane to give a 2,4-diethoxyphospholane. In all its reactions, PhP=W(CO)5 apparently behaves as a singlet electrophilic carbene.
