Contrasting Synergistic Heterobimetallic (Na–Mg) and Homometallic (Na or Mg) Bases in Metallation Reactions of Dialkylphenylphosphines and Dialkylanilines: Lateral versus Ring Selectivities

Abstract

A series of dialkylphenylphosphines and their analogous aniline substrates have been metallated with the synergistic mixed-metal base [(TMEDA)Na(TMP)(CH SiMe )Mg(TMP)] 1. Different metallation regioselectivities for the substrates were observed, with predominately lateral or meta-magnesiated products isolated from solution. Three novel heterobimetallic complexes [(TMEDA)Na(TMP)(CH PCH Ph)Mg(TMP)] 2, [(TMEDA)Na(TMP)(m-C H PiPr )Mg(TMP)] 3 and [(TMEDA)Na(TMP)(m-C H NEt )Mg(TMP)] 4 and two homometallic complexes [{(TMEDA)Na(EtNC H )} ] 5 and [(TMEDA)Na (TMP)(C H PEt)] 6 derived from homometallic metallation have been crystallographically characterised. Complex 6 is an unprecedented sodium-amide, sodium-phosphide hybrid with a rare (NaNNaP) ladder motif. These products reveal contrasting heterobimetallic deprotonation with homometallic induced ethene elimination reactivity. Solution studies of metallation mixtures and electrophilic iodine quenching reactions confirmed the metallation sites. In an attempt to rationalise the regioselectivity of the magnesiation reactions the C-H acidities of the six substrates were determined in THF solution using DFT calculations employing the M06-2X functional and cc-pVTZ Dunning's basis set.

Synthesis of Mixed Arylalkyl Tertiary Phosphines via the Grignard Approach

“…Proton-decoupled 31 P( 1 H) NMR spectra showed resonance between ~−7 ppm and −27 ppm (Supplementary Materials), which was significantly dependent upon the substituents (the more basic the phosphine, the more up-field the signal in the 31 P NMR spectra). In the past, one-or multi-step synthesis of compounds (2) [16,17] (3) [18], (4) [19], (5) [20], (7) [21], (9) [22], (10) [23], and (11) [24] has been reported, including by the Grignard method, with which our results match well. Moreover, in our method, the yields were comparable to the transition-metal-mediated synthesis with equally broad scope.…”

Supramolecular architectures sustained by delocalised C–I⋯π(arene) interactions in molecular crystals and the propensity of their formation

“…Similarly, molecules in 37 106 and 44 113 The molecules in 50, 119 51, 120 52, 121 53, 122 54, 123 55, 124 56 125 and 57 126 each carry two iodide substituents, see Fig. 6 for chemical diagrams.…”

“…The first category involves crystals 1, 70 4, 73 48, 117 51, 120 105, 169 155, 205 160, 222 164 226 and 181. 238 Of the nine crystals, five have congeners having C-X•••π(arene) interactions and of these, congeners of 4, 73 i.e.…”

“…bromide, 253 chloride 254 but, not fluoride 255 have C-X•••π(arene) interactions close to being classified as delocalised in terms of this survey. For congeners of 51, 120 i.e. chloride, 256 and 181, 238 i.e.…”

Regioselective functionalization of aryl azoles as powerful tool for the synthesis of pharmaceutically relevant targets

“…In line with this concept, Hagadorn showed that TMP 2 Zn is an excellent base for the α-zincation of various carbonyl compounds and the metalation of pyridine-N-oxide in toluene 34,35 . Similarly, Mulvey and co-workers [36][37][38][39][40][41][42][43] reported several mixed bimetallic amide bases for metalation reactions in non-coordinating hydrocarbon solvents. Herein we report a highly selective and broadly applicable magnesiation of various aryl azoles using the amide base TMPMgBu in a toluene/hexane solvent mixture and subsequent cross-couplings and electrophilic quench reactions.…”