Organophosphorus Compounds, 118. Reactions of 1‐Chloro‐1H‐phosphirenes with Nucleophiles

Abstract

The halogen atoms in the 1-chloro-1H-phosphirenes, 5a-c, are easily substituted on reaction with organolithium and Grignard reagents, 14a-p, with formation of the corresponding 0-, N-, C-, Si-, and Ge-substituted 1H-phosphirenes, 15a-t. Cl/H exchange reactions also occur on reaction with lithium metal hydrides (5a 4 17). Furthermore, substitution reactions are also realized with the alkali metal borates, 18a-g (-19a-g);the same is true for reactions with tnmethylsilyl cyanide and azide (-+22a-d). Some of the substitution products have been chardcterized in the form of their metal complexes, 16, 23, 24, and 25.

σ*-Aromaticity in Three-Membered Rings

“…Structures 1H-phosphirenes are available with a large variety of substitution patterns [3,29]. The 1H-Azirines, on the other hand, have only been found as very unstable intermediates [30].…”

The 1-Silyl-1H-phosphirene/1,2-Dihydrophosphasilete Rearrangement and Its Preparative Significance

“…This is indicative of a higher barrier to inversion at phosphorus. The ring expansion in 4 a is apparent from the marked shift of the 31 P NMR signal to low field: from d À 205 in 3 a [7] to d À 131 in 4 a. The 13 C NMR data provide further evidence for the constitution of the products: the signals of the sp 2 skeletal carbon atoms C3 and C4 are shifted by more than 30 ppm to lower field in comparison with those of 3 a.…”

“…The 13 C NMR data provide further evidence for the constitution of the products: the signals of the sp 2 skeletal carbon atoms C3 and C4 are shifted by more than 30 ppm to lower field in comparison with those of 3 a. [7] Additionally, the J(C,P) coupling constant for the signal of C4 is only 22.1 Hz. Small coupling constants of this type are a general feature of diphospha-and phosphacyclobutenes with l 3 s 3 phosphorus atoms.…”

“…[7] In this way, for example, the syntheses of cyano-, azido-, imido-, and phosphaalkene-substituted 1H-phosphirenes became possible. [1,2,7,8] Reactions with organometallic compounds, such as 2 a and 2 b, proceed under formation of lithium chloride to afford the 1-silyl-and 1-germyl-1H-phosphirenes 3 a and 3 b, respectively (Scheme 1). [8,9] Scheme 1.…”

“…Mass spectra were recorded on a Finnigan MAT 90 spectrometer. Compounds 3 a,b [7] were prepared by published methods. All other starting materials were purchased from commercial sources.…”