Synthesis of a natural product-inspired eight-membered ring lactam library via ring-closing metathesis

We have prepared a novel speculative eight-membered lactam demonstration library based on the skeletal structure of the potent antitumor marine natural product octalactin A. The basic scaffold was readily constructed in a convergent fashion via ring-closing metathesis chemistry from the corresponding diene amides. A cursory examination of the biological properties of the library validates the relevance and significance of these structures.     

Syntheses and characterization of diorganotin(IV) derivatives with areneseleninic acid: X-ray crystal structures of 1D infinite chains containing eight-membered ring

Three new diorganotin(IV) complexes, [Bu₂Sn(O₂SeC₆H₅)₂]_n (1), [Bu₂Sn(O₂SeC₆H₄Me)₂]_n (2), [Me₂Sn(O₂SeC₆H₄Bu)₂]_n (3) have been synthesized by the reaction of benzeneseleninic acid, p-tolueneseleninic acid, and 4-tert-butylbenzeneseleninic acid with Me₂SnCl₂ or Bu₂SnCl₂ in the presence of sodium ethoxide in methanol at 50 °C. All of the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy and X-ray crystallography. X-ray diffraction studies of 1, 2, 3 show that the areneseleninate groups behave as double bridges between the tin atoms leading to polymeric chain structure with Sn₂O₄Se₂ eight-membered ring. The organic groups bonded to the tin atoms are in trans-position in the resulting octahedral arrangement.