High Structural Control in Metal‐Mediated Synthesis of New Functionalized Diphosphines Using Diphosphinoketenimines as Precursors

Abstract

The diphosphinoketenimine ligand in the neutral complexes fac-[MnI(CO)(3){(PPh(2))(2)C=C=NR}] (1 a: R = Ph; 1 b: R = p-tolyl) undergoes nucleophilic attack by MeLi and nBuMgCl yielding, after hydrolysis, the diphosphinoenamine-containing complexes fac-[MnI(CO)(3){(PPh(2))(2)C=C(R')NHR}] (3 a,b: R' = Me; 4 a,b: R' = nBu). Complex 1 a reacts under the same conditions with H(2)C=C=CHMgBr to afford fac-[MnI(CO)(3){(PPh(2))(2)C=C(CH(2)CC[triple chemical bond]CH)NHR}] (5 a), which contains a terminal alkyne group on the alpha-carbon atom of the diphosphinoenamine ligand. The cationic complexes fac-[Mn(CO)(4){(PPh(2))(2)C=C=NR}](+) (6) react with H(2)C=C=CHMgBr to afford diphosphinomethanide derivatives bearing three different types of functional groups, depending upon the substituent on the nitrogen atom of the ketenimine: cumulene in fac-[Mn(CO)(4){(PPh(2))(2)C--C(CH=C=CH(2))=N-xylyl}] (7 d), internal alkyne in fac-[Mn(CO)(4){(PPh(2))(2)C--C(C[triple chemical bond]CCH(3))=NtBu}] (8), and quinoline in 9 (R = Ph), whose formation implies an unusual cyclization process. Protonation of 7 d, 8, and 9 with HBF(4) occurs at the nitrogen atom to give the cationic derivatives 10 d, 11, and 12, respectively, which contain the corresponding functionalized diphosphine ligands. Irradiation of 3 a,b and 4 a,b with Vis/UV light makes it possible to isolate the free ligands (PPh(2))(2)C=C(R')NHR (13 a,b and 14 a,b), completing the metal-assisted synthesis of these novel functionalized diphosphines. Irradiation of 12 with Vis/UV light generates free phosphinoquinoline ligand 15, which readily affords a complex 16 containing 15 as a P,N-chelating ligand when treated with [PdCl(2)(NCMe)(2)], thus demonstrating its coordination capability.

Formation of P−C Bonds under Unexpectedly Mild Conditions. Phosphoryl Migration and Metal Coordination of Diphenylphosphinomethyl-oxazolines and -thiazolines

“…The geometry around the sp 2 -hybridized C4 carbon atom is planar, the sum of the P−C−P and P−C−C angles being 359.69(2)°. These structural features are similar to those found in related metal complexes containing the chelating diphosphine obtained by deprotonation of (Ph 2 P) 2 CHPy or its substituted analogues. , N-functionalization on the oxazoline ring with other metal centers offers the potential to generate new heterometallic complexes, and this reactivity is currently under study.…”

A three-component reaction involving isocyanide, phosphine and ketenimine functionalities

“…Some years ago we reported the synthesis of keteniminefunctionalized diphosphines of formula (PPh 2 ) 2 CQCQNR, 1 and their reactivity with alkynes and heterocumulenes to obtain unique phosphorus heterocycles. 2 We also proved that, upon coordination to a metal center, the ketenimine group in these diphosphines become activated toward nucleophilic addition of organolithium and organomagnesium reagents 3 and amines, 4 allowing the formation of a variety of highly functionalized diphosphines. Even weak nucleophiles such as isocyanides were able to react with coordinated N-aryl diphosphinoketenimines yielding indole-functionalized diphosphines.…”

“…4a: 1 H NMR (300 MHz, CD 2 Cl 2 , 25 1C): d = 0.62 (s, 9H, CH 3 (tBu)), 1.56 (t, 3 J(H,H) = 7 Hz, 3H, OCH 2 CH 3 ), 4.65 (q, 3 J(P,H) = 3 J(H,H) = 7 Hz, 2H, OCH 2 CH 3 ), 6.2-7.9 ppm (26H, Ph and CQCH); 13 C{ 1 H} NMR (75.5 MHz, CD 2 Cl 2 , 25 1C): d = 17.3 (d, 3 J(P,C) = 7 Hz, OCH 2 CH 3 ), 28.9 (s, CH 3 (tBu)), 52.8 (d, 1 J(P,C) = 18 Hz, P 2 C), 58.2 (s, C(CH 3 ) 3 ), 65.7 (d, 2 J(P,C) = 6 Hz, OCH 2 CH 3 ), 152.2 (s, C ipso NPh), 156.6 (d, 2 J(P,C) = 12 Hz, CQCH), 169.2 ppm (dd, 2 J(P,C) = 8 Hz, 2 J(P,C) = 2 Hz, C-NPh); 31 P{ 1 H} NMR (121.4 MHz, CD 2 Cl 2 , 25 1C): d = À14.5 (d, 2 J(P,P) = 181 Hz, Ph 2 PQO), 57.8 ppm (d, 2 J(P,P) = 181 Hz, Ph 2 PQC). 5a: 1 H NMR (300 MHz, CD 2 Cl 2 , 25 1C): d = 0.86 (s, 9H, CH 3 (tBu)), 1.56 (t,3 J(H,H) = 7 Hz, 3H, OCH 2 CH 3 ), 2.87 (s, 2H, CH 2 ), 4.76 (q, 3 J(P,H) = 3 J(H,H) = 7 Hz, 2H, OCH 2 CH 3 ), 6.0-7.9 ppm (25H, Ph);13 C{ 1 H} NMR (75.5 MHz, CD 2 Cl 2 , 25 1C): d = 16.6 (d, 3 J(P,C) = 6 Hz, OCH 2 CH 3 ), 28.7 (s, CH 3 (tBu)), 44.2 (d, 2 J(P,C) = 8 Hz, CH 2 ), 50.6 (s, C(CH 3 ) 3 ), 65.5 (d, 2 J(P,C) = 6 Hz, OCH 2 CH 3 ), 151.2 (s, C ipso NPh), 172.1 ppm (d, 2 J(P,C) = 8 Hz, CQNPh); 31 P{ 1 H} NMR (121.4 MHz, CDCl 3 , 25 1C): d = 21.4 (d, 2 J(P,P) = 54 Hz, Ph 2 PQO), 50.6 ppm (d, 2 J(P,P) = 54 Hz, Ph 2 PQC). y Crystal data for 3a (C 37 H 36 N 2 OP 2 ÁCH 2 Cl 2 ): M = 671.54, crystal size 0.13 Â 0.10 Â 0.08 mm, a = 11.6478(6) A ˚, b = 18.985(1) A ˚, c = 16.179(1) A ˚, b = 99.847(4)<, V = 3525.0(4) A ˚3, r calcd = 1.265 g cm À3 , m = 2.76 mm À1 , Z = 4, monoclinic, space group P21/n, l = 1.54184 A ˚, T = 293(2) K, y max = 70, independent reflections = 6543, refined parameters = 546, largest diff.…”