Synthesis of 5-substituted pyrimidines. ortho-directed lithiation of pyrimidine derivatives

ortho-Directed lithiation of some pyrimidines has been investigated. Treatment of 2- and/or 4-alkoxy or acylaminopyrimidine with lithium 2,2,6,6-tetramethylpiperidide in ether at 0°, followed by quenching with various electrophiles afforded the corresponding 5-substituted pyrimidines.     

Synthesis of quinazoline derivatives through anionic cycloaddition reactions of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate with acetylenes and olefins

The anionic cycloaddition of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate has been investigated. The lithium salt of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate, generated by deprotonation with lithium diisopropylamide in ether at – 70°, reacted smoothly with electron deficient acetylenes and olefins to give quinazoline derivatives in a single step.     

Oxido-bridged di-, tri-, and tetra-nuclear iron complexes bearing bis(trimethylsilyl)amide and thiolate ligands

A series of di-, tri-, and tetra-nuclear iron-oxido clusters with bis(trimethylsilyl)amide and thiolate ligands were synthesized from the reactions of Fe{N(SiMe(3))(2)}(2) (1) with 1 equiv of thiol HSR (R = C(6)H(5) (Ph), 4-(t)BuC(6)H(4), 2,6-Ph(2)C(6)H(3) (Dpp), 2,4,6-(i)Pr(3)C(6)H(2) (Tip)) and subsequent treatment with O(2). The trinuclear clusters [{(Me(3)Si)(2)N}Fe](3)(μ(3)-O){μ-S(4-RC(6)H(4))}(3) (R = H (3a), (t)Bu (3b)) were obtained from the reactions of 1 with HSPh or HS(4-(t)BuC(6)H(4)) and O(2), while we isolated a tetranuclear cluster [{(Me(3)Si)(2)N}(2)Fe(2)(μ-SDpp)](2)(μ(3)-O)(2) (4) as crystals from an analogous reaction with HSDpp. Treatment of a tertrahydrofuran (THF) solution of 1 with HSTip and O(2) resulted in the formation of a dinuclear complex [{(Me(3)Si)(2)N}(TipS)(THF)Fe](2)(μ-O) (5). The molecular structures of these complexes have been determined by X-ray crystallographic analysis.     

Aggregate of a peptide-containing block copolymer with a lipase

The peptide-containing block copolymer poly(N-acetyliminoethylene)-block-poly(L -phenylalanine) (1) formed large water-soluble aggregates in water due to the hydrophobic and hydrogen-bonding character of the poly(L -phenylalanine) block. The solution properties of 1 were compared with those of the block copolymer poly(N-acetyliminoethylene)-block-poly(N-benzoyliminoethylene) (2) with an analogous structure. 1 formed aggregates even though the poly(phenylalanine) segment was short as compared with 2 in which hydrophobic interaction may be the only driving force to form aggregates. The aggregates have strong capability of incorporating Lipase P and largely increase the hydrolysis activity against p-nitrophenyl propionate as compared with that of free Lipase P.