LOW-VALENT TITANIUM INDUCED REDUCTIVE CYC LIZATION OF (3-OXO-1,3-DIARYL) PROPYLPROPANEDINITRILE

This paper reports the reactions of low-valent titanium reagent(TiCl4- Zn system) with (3-oxo-1,3-diaryl) propylpropanedinitrile. It is found that the low-valent titanium can promote a novel cyclization of (3-ox o-1,3-diaryl)propylpropanedinitrile to give 2-cyano-3,5-diary-1-aminoc yclopentene, trans and cis 2-amino-3-cyano-1, 4-diary-2-cyclopentene-1 -ol. The latter's configurations are determinated by X-ray diffraction analysis. The crystal of compound 3c is triclinic with space group P (1) over bar, a=1.038 9(4) nm, b=1.229 2(4) nm, c=0.802 7(3) nm, 7 alp ha=93.29(3)degrees, r=113.32(3)degrees, V=0.936 2(6) nm(3), Z=2, D-c=1 .193 9 g/cm(3), mu=0.77 cm(-1), F(000)=360, and find R=0.067 and R-w=0 .057 for 130 8 reflections (I>3 sigma(I)). The crystal of compound 4a is orthorhombic with space group Pbcn, a=1.337 0(5) nm, b=1.048 1(5) n m, c=2.335 0(6) nm, V=3.272(3) nm(3), Z=8, D-c= 1.262 g/cm(3), mu=2.36 cm(-1). F(000)=129 6, and find R=0.043 and R-w=0.049 for 142 6 reflec tions (I>3 sigma(I)). A possible reaction mechanism is proposed in thi s paper.