Phosphatriafulvenes - phosphaalkenes with inverse electron density

Phospha‐Organic Chemistry: Panorama and Perspectives

“…[31]. 1 [10] 2 [11] 3 [8] 4 [12] P R P R Cp*(Et 3 P)Ni P C SiMe 3 SiMe 3 H P C NMe 2 NMe 2 5 [14] 6 [15] 7 [17] …”

“…Reactions with protic reagents can either lead to CÀH (normal) or PÀH (inverse) products depending upon the polarity of the bond [Eqs. (14), (15)]. [8,46] Classical reactions of olefins, such as catalytic hydrogenation [47] and epoxidation [48] can only be achieved after [49] whereas hydrozirconation [50] leads to the P À H products [Eqs.…”

“…[121] This dimer is the starting point for some very useful chemistry. Upon chlorination under mild conditions using C 2 Cl 6 , it yields the free 1,3-diphosphacyclobutadiene (14) which dimerizes to give the corresponding tetraphosphacubane [see Eq. (47)].…”

“…Cyclopropylidene derivatives, such as 5, also belong to this category. [14] 31 P NMR spectroscopy provides an easy means of discriminating between the two categories. Normal phosphaalkenes display 31 P resonances at low field, generally around d = + + 200 ppm (e.g., 3, d 31 P = + + 233 ppm), [8] although much lower-field chemical shifts have been recorded (e.g., 6, d 31 P = + 740 ppm).…”

Synthesis and Properties of 4,5,6‐Triphospha[3]radialene

“…However, studies of heteroatom-containing [3]radialene derivatives have been quite limited because of their instability, [4b, 7] whereas some [4] or [6]radialene derivatives that contain nitrogen, [8] oxygen, [9] phosphorus, [10] or sulfur atoms [9b] in the framework have been isolated, and their characteristic properties that are derived from their carbonheteroatom p-bond demonstrated. Herein, we report the synthesis of a stable triphospha[3]radialene derivative 5, in which the three exo-carbon atoms of the [3]radialene skeleton are replaced by phosphorus atoms.The reaction of tetrachlorocyclopropene [11] with the bulky (2,4,6-tri-tert-butylphenyl)phosphine [12] in the presence of 2,6diisopropylaniline as a base gave a diastereomeric mixture of 4-phosphatriafulvenes [13] 6 as a stable orange solid in 66 % yield (Scheme 2). Oxidation of 6 with iodine in the presence of triethylamine afforded 5 as a deep-purple solid in 92 % yield.…”