Concise Synthesis of Enantiopure (S)-(+)-2,2′-Bis(tert-butyldimethylsilyl)-1,1′-diphosphaferrocene: Anion-Dependence of Its Coordination to Palladium(II) Centers

Abstract

A conVenient synthesis of enantiopure (S)-(+)-2,2′bis(tert-butyldimethylsilyl)-3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene is described. The compound shows unusual coordination properties with respect to Otsuka's Pd(II) dimer di-(S)-chloro-[1-[1-(dimethylamino)ethyl]-2-naphthyl-C,N]palladium(II)].

Double Friedel–Crafts Acylation Reactions on the Same Ring of a Metallocene: Synthesis of a 2,5‐Diacetylphospharuthenocene

“…Compound 22 : A freeze/thaw‐cycled solution of potassium 2‐( tert‐ butyldimethylsilyl)‐3,4‐dimethylphospholide (630 mg, 2.38 mmol)114 in THF (10 mL) was treated with solid [{RuCp*Cl} 4 ] (650 mg, 2.39 mmol) at room temperature and the mixture was stirred for 30 min. The dark solution was treated with methanol (2 mL) and chlorotrimethylsilane (0.5 mL) and allowed to stir for a further three hours.…”

Resolution and determination of the absolute configuration 2,2′-diacetyl-3,3′, 4,4′-tetramethyl-1,1′-diphosphaferrocenes

“…There have been reports of the resolution or enantioselective syntheses of planar chiral azaferrocenes [3], phosphaferrocenes [4], 2-substituted-1,1 0 -diphosphaferrocenes [5] and bis-2,2 0 -disubstituted-1,1 0 -diphosphaferrocenes [6,7].…”

“…The first separation of bis substituted 3,3 0 , 4,4 0 -tetramethyl-1,1 0 -diphosphaferrocenes was done by preparative HPLC on Daicel Chiracel OD column [6]. In contrast (S)-(þ)-2,2 0 -Bis(tert-butyldimethylsilyl)-1,1 0 -diphosphaferrocene was resolved by diastereo palladium complex formation [7].…”

Synthesis and Evaluation of Side-Arm-Alkylated Phosphametallocene Phosphines

“…Thus it seemed likely that elaborating the side arm of the phosphametallocen-2-ylmethylphosphines should also set up conformational relays that might modify ligand properties and performance quite profoundly. Well-developed functionalization chemistry of this kind is available only for rac- phosphaferrocenes, a class that includes an analogue of compound 2 described here; the generation of enantiopure phosphametallocenes, − ,,− or those based upon late transition metals other than iron, − ,,− is still in its infancy. The study presented here shows that resolved ligands having side-arm C-functionalization are quite easily accessed from the readily available enantiopure phospharuthenocene source 7 , through syntheses that exploit the extreme stability ,,, of the previously unknown mono- and dimethyl-substituted phospharuthenocenemethylium ions.…”