Diphosphonio Isophosphindoles, Phospholes with a Planar Phosphorus

Abstract

rate law with rate constant kobs (equations (a)-(d)). For route @ where k, 2 k,, equation (a) applies. kobs = k, [aIkene] (a)For route @ with d[Z]/dt = 0, the observed rate constant is described by equation (b),which reduces to equation (c) or (d). kobs = k , , when k,[alkene] k _ (c) kobs = (k,k,/k-1) [alkene], when k, [alkene] < k _ (d) We followed the decrease in concentration of 1 a in benzene in the presence of excess NPM by analytical HPLC.[14. ''I The dependence of the kobs values obtained from the function In [l] = In [I],-kobs t (correlation coefficient r 2 0.999) on [NPM] at T = 303 K is plotted in Figure 1. Already at rela-I l o ' kobr I d T 0.0 2 :L O L 0.8 1.2 INPMI-Irnol.L-'l Fig. 1. k,,, =d[laj/dt as a function of [NPM]; see text. Conditions: T = 303 K, solvent benzene, [la] = 0.035 mol L-*, 2.5-to 39.9-fold excess of NPM. tively low excess of NPM a plateau is reached, that is the condition, k,[alkene] + k-of Eq. (c) is satisfied. Thus route 0, via the diazoalkene intermediate 2a, is confirmed by the kinetic study. From the temperature dependence of the limiting rate constant k , for T = 293-303 K, the following activation parameters were calculated: E, = 21.6 * 0.4 kcal mol-I, AH' = 21.0 0.4 kcal mol-', AS* = -3.4 1.2 cal K-' mol-'. In an analogous study with norbornadiene as trapping agent,['61 a plot of the dependence of rate on concentration of norbornadiene yields a line through the origin. This relationship is described by equations (a) and (d) and no distinction between routes @ and 0can be made.

2-stannaindenes and 2-stannaindanes

“…As for 2, the signal is split, by a one-and a three-bond 31 P coupling, to a double doublet. Both coupling constants are much higher than for 2 and are close to those of 1 [4] (see above).…”

“…An electron withdrawing substituent such as a phosphonio group at a carbon ring member should further withdraw charge from the heteroatom and thus stabilize its two-coordination. This effect had been used successfully for the synthesis of a diphosphonio-isophosphindolide 1 [4][5][6]. We intended to use this effect now also for a doubly charged ring system and chose 1,3-bis(triphenylphosphonio)-2-stannaindenediide 2 as a target compound.…”

The Continuing Development of the Chemistry of Phospholes

“…It [76] in stable form with two triphenylphosphonio substituents (186), and was the subject of considerable later work by Gudat and colleagues [77]. Much of this work is concerned with coordination chemistry of the species, but pertinent to the present discussion is a recent study which described modification of the phosphonio group or groups to give simpler species.…”

Synthesis and Basic Coordination Properties of Side-chain Functionalized Bis-phosphonio-benzophospholides

“…Conversion into trifluoromethanesulfonate (OTf) or BPh 4 salts was easily possible by anion exchange with LiOTf or NaBPh 4 , respectively. Formation of the cation 2 d was also observed when 6 was directly reacted with PCl 3 /NEt 3 as originally reported by Schmidpeter et al for the synthesis of 1 [9], but owing to decomposition during the aqueous workup procedure only impure products were isolated and this protocol was therefore abandoned. By analogy to known reactions of b-functionalized phosphonium salts [7], the phosphination of the 2-chloroethyl-phosphonio moiety in 4 is thought to proceed via base (LiPPh 2 ) promoted dehydrochlorination to give first a transient vinylphosphonium species which is converted to the ylide 5 by addition of HPPh 2 and final deprotonation.…”

“…±464 (2) 2335 (2) 2643 (2) 19(1) C (6) ±171 (3) 3374 (2) 2498 (2) 21(1) C (7) 879 (2) 3747 (2) 2427 (2) 19(1) C (8) 1670 (2) 3077 (2) 2493 (2) 15(1) C (9) 2808 (2) 3296 (2) 2455 (2) 16(1) P (2) 2167(1) 130(1) 2868(1) 14(1) C (10) 3439 (2) ±343 (2) 2852 (2) 16(1) C (11) 3511 (3) ±1179 (2) 2137 (2) 22(1) C (12) 4507 (3) ±1539 (3) 2188 (3) 27(1) C (13) 5426 (3) ±1062 (3) 2942 (3) 27(1) C (14) 5365 (3) ±228 (3) 3648 (2) 25(1) C (15) 4371 (3) 126 (2) 3614 (2) 22(1) C (16) 1072 (2) ±672 (2) 1882 (2) …”