Synthesis and absolute configuration of planar chiral ferrocenophanes by amide-directed ortho-lithiation

trans-1,2-Diaminocyclohexane has been used as the backbone of the chiral macrocycles of amido- and amino-ferrocenophanes. Planar chirality was introduced via a self assembled amide-directed diastereoselective ortho-lithiation. Detailed NMR analysis revealed the (Rp)-configuration in the newly synthesised compounds.

Figure optionsDownload as PowerPoint slide

(R,R)-1,1′-[N,N′-(1,2-Cyclohexane-1,2-diyl)bis(N-methylcarboxamide)]ferroceneC20H24FeN2O2Ee = 98%[α]D=+128.4[α]D=+128.4 (c 0.43, CHCl3)Source of chirality: (R,R)-1,2-diaminocyclohexane (98% ee)Absolute configuration: (R,R)

(R,R,Rp)-1,1′-[N,N′-(1,2-Cyclohexane-1,2-diyl)bis(N-methylcarboxamide)]2-methylferroceneC21H26FeN2O2De >98.5 % (NMR)[α]D=+0.7[α]D=+0.7 (c 1.03, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R,R,Rp)

(R,R,Rp,Rp)-1,1′-[N,N′-(1,2-Cyclohexane-1,2-diyl)bis(N-methylcarboxamide)]2,2′-dimethylferroceneC22H28FeN2O2De >98.5 % (NMR)[α]D=-10.5[α]D=-10.5 (c 0.14, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R,R,Rp,Rp)