甘油骨架上含芳硒基的替加氟硫代磷脂缀合物的合成及生物活性

以O-(2-邻苯二甲酰亚氨基)乙基-1,3,2-二氧磷杂环戊烷硫代磷酸酯1及2-邻苯二甲酰亚氨基乙醇环甘油硫代磷脂缀合物2为模型,研究开环反应的条件.结果表明,在室温下,甲醇对化合物1中1,3,2-二氧磷杂环戊烷中的磷原子的亲核进攻,生成O-甲基-O-羟乙基-O-(2-邻苯二甲酰亚氨基)乙基硫代磷酸酯3,但是在此条件下,甲醇与化合物2不反应.在室温下,以异丙醇作溶剂,苯硒酚与化合物2不反应.在氢氧化钾存在下,以异丙醇/水作溶剂(体积比20:1),在室温下,硒酚可以有效地进攻中化合物2中1,3,2-二氧磷杂环戊烷中的碳原子生成相应的开环产物.按照这一反应条件,顺利实现了硒酚对N¹-(2-呋喃基)-N³-羟烷基-5-氟脲嘧啶硫代环甘油磷脂缀合物的亲核开环,生成甘油骨架的端碳原子上带有芳硒基新颖的磷脂核苷缀合物.对开环反应的机理进行了探讨.体外细胞毒性试验结果表明:产物对膀胱癌细胞T-24、胃癌细胞BGC-823的恶性增殖抑制效果优于替加氟;但对正常肝上皮细胞毒性也大于替加氟.     

One-pot synthesis of linear- and three-arm star-tetrablock quarterpolymers via sequential metal-free ring-opening polymerization using a “catalyst switch” strategy

A “catalyst switch” strategy has been used to sequentially polymerize four different heterocyclic monomers. In the first step, epoxides (1,2-butylene oxide and ethylene oxide) were successively polymerized from a monohydroxy or trihydroxy initiator in the presence of a strong phosphazene base promoter (t-BuP₄). Then, an excess of diphenyl phosphate (DPP) was introduced, followed by addition and polymerization of a cyclic carbonate (trimethylene carbonate) and a cyclic ester (δ-valerolactone or ε-caprolactone). DPP acted as both neutralizer of the phosphazenium alkoxide (polyether chain end) and activator of the cyclic carbonate/ester. Using this method, linear- and star-tetrablock quarterpolymers were prepared in one pot. This work is emphasizing the strength of the previously developed catalyst switch strategy for the facile metal-free synthesis of complex macromolecular architectures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 304–312     

Optimization of Grignard ring-opening of α-brominated dioxolanes for the preparation of β-hydroxy-protected vinyl ethers by a three-step one-pot procedure

Aliphatic, cyclic, and aromatic benzoate-protected γ-hydroxy enol ethers were prepared from α-brominated dioxolanes by a three-step reaction procedure and a one-pot protocol involving Grignard reagent formation, ring-opening, and final benzoate protection. Additionally, tert-butyldiphenylsilyl, acetate, and 4,4′-dimethoxytrityl were also successfully used as alternative protecting groups.     

One-pot synthesis of 5-sulfonamidopyrazole from terminal alkynes, sulfonyl azides and hydrozones

5-Sulfonamidopyrazoles were efficiently synthesized from terminal alkynes, sulfonyl azides and hydrozones. The sequential reaction involves a copper-catalyzed three-component reaction, a Lewis acid-catalyzed electrocyclic reaction and a dehydrogenation.     

Rethinking Cysteine Protective Groups: S‐Alkylsulfonyl‐l‐Cysteines for Chemoselective Disulfide Formation

The ability to reversibly cross‐link proteins and peptides grants the amino acid cysteine its unique role in nature as well as in peptide chemistry. We report a novel class of S‐alkylsulfonyl‐l ‐cysteines and N‐carboxy anhydrides (NCA) thereof for peptide synthesis. The S‐alkylsulfonyl group is stable against amines and thus enables its use under Fmoc chemistry conditions and the controlled polymerization of the corresponding NCAs yielding well‐defined homo‐ as well as block co‐polymers. Yet, thiols react immediately with the S‐alkylsulfonyl group forming asymmetric disulfides. Therefore, we introduce the first reactive cysteine derivative for efficient and chemoselective disulfide formation in synthetic polypeptides, thus bypassing additional protective group cleavage steps.     

Ring-opening reactions of oxetanes: A review of methodology development and synthetic applications

Ring-opening reactions of oxetanes yield important functionalized products depending upon the nature of nucleophiles as well as substitution pattern on the oxetane ring. Ring opening of oxetanes can be carried out under a variety of reaction conditions. In this review article, an up-to-date overview of major synthetic methodologies involved in the ring opening of oxetanes as well as their synthetic applications has been presented.     

Ring opening metathesis polymerization of norbornene and tetracyclododecene with cyclooctene by using (arylimido)vanadium(V)–alkylidene catalyst

Ring opening metathesis polymerizations (ROMP) of norbornene (NBE), tetracyclododecene (TCD) in the presence of cis-cyclooctene (COE) using vanadium-alkylidene catalyst, V(CHSiMe₃)(N-2,6-Cl₂C₆H₃)(OC₆F₅)(PMe₃)₂ ( 1 ), were explored. The polymerizations with TCD afforded high-molecular-weight polymers (M_n = 19,500–47,400) with low PDI (M_w/M_n) values (1.18–1.38) which possess microstructure of repeated ring-opened TCD and certain methylene units by incorporation of ring-opened COE on the basis of microstructure analysis by NMR spectra and DSC thermograms; hydrogenated copolymer possessed melting temperature at 294 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3067–3074