Efficient and/or selective methylation by diazomethane of alcohols, halo alcohols, glycols, amino alcohols and mercapto alcohols with the use of a proton-exchanged X-type zeolite as an acid-base bifunctional catalyst
Reactions of diazomethane with butanol, allyl alcohol and β- and γ-halo alcohols led to efficient methylation (giving the corresponding methyl ethers) with the use of a proton-exchanged X-type zeolite compared with H2SO4. The reactions with propylene and isobutylene glycols using the zeolite provided regioselectivemethylation of the primary OH rather than the secondary or tertiary OH, whereas regioselectivity
与H 2 SO 4相比,使用质子交换的X型沸石,重氮甲烷与丁醇,烯丙醇以及β-和γ-卤代醇的反应导致有效的甲基化(得到相应的甲基醚)。使用沸石与丙烯和异丁二醇的反应提供了伯羟基而不是仲或叔羟基的区域选择性甲基化,而在使用H 2 SO 4的反应中未观察到区域选择性。在沸石而不是H 2 SO 4的存在下,与2-氨基乙醇和2-巯基乙醇的反应分别显示出高化学选择性的S-甲基化和N-单甲基化。该反应机理涉及沸石的酸碱双功能催化,其中酸性位点与重氮甲烷反应形成其共轭酸,碱性位点与沸石的相互作用增强了OH和SH基的亲核性。组的质子。
Ring-selective synthesis of O-heterocycles from acyclic 3-O-allyl-monosaccharides via intramolecular nitrone–alkene cycloaddition
作者:Tony K.M Shing、Yong-Li Zhong
DOI:10.1016/s0040-4020(00)01138-8
日期:2001.2
Intramolecular1,3-dipolarcycloadditions of nitrones formed from 3-O-allyl-d-glucose and d-altrose (both with threo-configuration at C-2,3) afford oxepanes selectively whereas the same reactions of nitronesderivedfrom 3-O-allyl-d-allose and d-mannose (both with erythro-configuration at C-2,3) give tetrahydropyrans selectively.
The use of sulfonylamido pyrimidines incorporating an unsaturated side chain as endothelin receptor antagonists
作者:Martin H Bolli、Christoph Boss、Martine Clozel、Walter Fischli、Patrick Hess、Thomas Weller
DOI:10.1016/s0960-894x(02)01084-3
日期:2003.3
A series of compounds structurally related to bosentan 1 featuring an unsaturatedsidechain at position 6 of the core pyrimidine have been studied for their potential to block the ET(A) and ET(B) receptor. Incorporation of a 2-butyne-1,4-diol linker bearing a pyridyl carbamoyl moiety led to in vitro highly potent endothelin receptor antagonists (e.g., 70 and 75). The propargyl derivative 26 significantly
Chemoselective Activation of Diethyl Phosphonates: Modular Synthesis of Biologically Relevant Phosphonylated Scaffolds
作者:Pauline Adler、Amandine Pons、Jing Li、Jörg Heider、Bogdan R. Brutiu、Nuno Maulide
DOI:10.1002/anie.201806343
日期:2018.10
Phosphonates have garnered considerable attention for years owing to both their singular biological properties and their synthetic potential. State‐of‐the‐art methods for the preparation of mixed phosphonates, phosphonamidates, phosphonothioates, and phosphinates rely on harsh and poorly selective reaction conditions. We report herein a mild method for the modular preparation of phosphonylated derivatives