[d]-Carbon–carbon double bond engineering in diazaphosphepines: a pathway to modulate the chemical and electronic structures of heteropines

We report the first examples of 7-membered diazaphosphepines using phosphorus–amine (P–N) chemistry.


General synthesis of B-and O-In
In a 1-necked 150-mL Schlenk flask, dibromo or diiodo moieties (1.0 mole eq.) was mixed with indole-2boronic acid pinacol ester (2.2 mole eq.), tris(dibenzylideneacetone)dipalladium(0) (0.05 mole eq.), tri-tertbutylphosphonium tetrafluoroborate (0.25 mole eq.), and potassium phosphate (9.0 mole eq.) in a mixture of THF and water (4:1 v/v) or toluene and water (4:1 v/v). The resulting mixture was degassed for 10 min, then refluxed under argon overnight. The reaction mixture was allowed to cool to room temperature, after which it was poured into 10 mL of water. The organic layer was extracted with chloroform. The crude product was purified by flash chromatography using dichloromethane and hexanes as eluent (from 1:9 to 4:6 by volume) to obtain B-and O-In.
The reaction mixture was allowed to cool to room temperature, after which it was poured into 10 mL of water.
The organic layer was extracted with chloroform. The crude product was purified by flash chromatography using dichloromethane and hexanes as eluent (from 1:9 to 4:6 by volume).

General Synthesis of B-and O-Ps:
In a 1-necked 150-mL Schlenk flask, phenylphosphine dichloride (1.0 mole eq.) was added to an acetonitrile solution of B-or O-In (1.0 mole eq.) in the presence of triehtylamine (2.0 mole eq.) at 0 o C. The resulting mixture was refluxed under argon overnight. The reaction mixture was allowed to cool to room temperature. Acetonitrile was removed under vacuum. The crude product was purified by flash chromatography using dichloromethane and hexanes as eluent (from 1:9 to 9:1 by volume) to obtain B-and O-P.
BZ-P was obtained as a white solid (Yield: 55%   was purified by flash chromatography using dichloromethane and hexanes as eluent (from 1:9 to 9:1 by volume) to obtain B-and O-P-Rs.      The absence of its second indole leg in CP-In results in a substantial blue shift in the absorption spectrum of mCP-In; this blue shift is more substantial than that observed when comparing the absorption spectra of FBZ-In with mFBz-In. This observation further supports our hypothesis that derivatives with aromatic substitutions exhibit strong electronic confinement.                              S33 Figure S38. 1 H NMR spectrum of FBZ-P in CDCl 3 . Figure S39. 13 C NMR spectrum of FBZ-P in CDCl 3 .

MI-PO-C8
S34 Figure S40. 1 H NMR spectrum of BTD-P in CDCl 3 . Figure S41. 1 H NMR spectrum of BTD-P in CDCl 3 . Figure S42. 1 H NMR spectrum of CP-P in CDCl 3 . Figure S43. 13 C NMR spectrum of CP-P in CDCl 3 . Figure S44. 1 H NMR spectrum of MI-P in CDCl 3 . Figure S45. 13 C NMR spectrum of MI-P in CDCl 3 . Figure S46. 1 H NMR spectrum of AN-P in CDCl 3 . Figure S47. 13 C NMR spectrum of AN-P in CDCl 3 .