Polymerization of hydroxyacetylenes by ruthenium alkylidene complexes

Polymerization of a series of acetylenes with a hydroxy functional group was investigated by using modified 2nd generation Grubbs (A) and Grubbs–Hoveyda (B) initiators. Owing to excellent tolerance for polar functional groups, catalysts A and B polymerized 3-butyn-2-ol (1), 2-methyl-3-butyn-2-ol (2) and 3-butyn-1-ol (3). The catalytic activities of catalyst B were greater than those of initiator A for these polymerizations. The steric bulk and the position of hydroxyl group of the monomer had an influence on the rate of polymerization. In order to investigate the role of hydroxyl group of monomers in the polymerization, the reaction between hydroxyacetylenes and the ruthenium complexes were monitored by ¹H NMR spectroscopy. The results revealed the formation of new alkylidene species via α-insertion. The calculated relative energies of propagating species formed in the reaction of A with monomer 1 suggested the formation of oxygen-chelated species. The structures of resulting polymers were characterized by various methods such as NMR, IR and UV–Vis spectroscopies. The ruthenium initiators gave polymers with different geometric structure of main chain than conventional catalysts.     

Synthesis and reactions of the optically active selenols derived from monoterpenes

A convenient methodology for the synthesis of optically active selenols, derived from p-menthane, carane, and pinane, is described. The selenols were oxidized with air to give the optically active diselenides, and were also converted into the corresponding allylic selenides via reaction with Z- and E-cinnamyl, geranyl, and neryl chlorides. Oxidation of the allylic selenides with mCPBA gave the optically active alcohols via [2,3]-sigmatropic rearrangement of the in situ generated allylic selenoxides.     

Synthesis of Novel Polycationic Quaternary Di‐ and Trispirocyclic Benzenes

Treatment of hexakis(bromomethyl)benzene with a cyclic amine {morpholine, 1‐methylpiperazine, 1‐(2‐hydroxyethyl)piperazine, isonipecotamide, 4‐hydroxypiperidine, 4‐[3‐(4‐piperidyl)propyl]‐1‐piperidineethanol} gave a range of di‐ and trispirocyclic ammonium salts in satisfactory yields (22–62%). Presumably, the electrostatic and repulsion forces play an important role in their formation. The structure in solution and the protonation site have been investigated by NMR and IR spectroscopy.     

On Euler–Jaczewski sequence and Remmert–Van de Ven problem for toric varieties

Let X be a complete toric variety and Y a smooth projective variety with . We prove that, if is a surjective morphism then . Received: 15 May 2001; in final form: 22 October 2001/ Published online: 4 April 2002     

Improved Oxidation of Naringenin to Carthamidin and Isocarthamidin by Rhodotorula marina

A novel single-step microbial transformation process for the efficient production of carthamidin and isocarthamidin from naringenin by yeast Rhodotorula marina in an aerated bioreactor was described. The biotransformation led to the total product concentration of 233 mg/l. The highest conversion efficiency observed for carthamidin was 0.31 mg/mg of naringenin and for isocarthamidin 0.47 mg/mg of naringenin.