Synthesis of Six-Membered Compounds by Environmentally Friendly Cyclization Using Indirect Electrolysis
摘要:
[Ni(cyclam)](ClO4)(2)-catalyzed indirect electroreduction of olefinic bromides produced six-membered compounds in low to high yields. The synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner. Lactam 66, the synthetic precursor of tacamonine, was prepared in 49% yield as a mixture of two diastereoisomers. The electrolysis of the bromoacetates gave the debrominated compounds in good yields.
Palladium-Catalyzed Intermolecular Heck-Type Reaction of Epoxides
作者:Shenghan Teng、Malcolm E. Tessensohn、Richard D. Webster、Jianrong Steve Zhou
DOI:10.1021/acscatal.8b02029
日期:2018.8.3
palladium-catalyzed intermolecular Heck-type reaction of both cyclic and acyclic epoxides is reported with tolerance of typical polar groups and acidic protons. Suitable alkenes include styrenes, conjugate dienes, and some electron-deficient olefins. In reactions of aliphatic terminal epoxides, ring opening occurs selectively at terminal positions, and stereocenters of epoxides are fully retained. Mechanistic studies
A polyphenylene ether resin composition containing the following Components (A) to (D) according at the following formulation ratio.
(A) 50 to 99.5 parts by weight of a polyphenylene ether
(B) 0.1 to 50 parts by weight of a partially hydrogenated aromatic alkenyl compound-conjugated diene block copolymer having a hydroxy group
and based on 100 parts by weight of the above resin composition,
(C) 0 to 950 parts by weight of a thermoplastic resin
and
(D) 0 to 10 parts by weight of a phosphorous acid triester
(EN) A chiral, organometallic compound which, at a molecular level, has no C2 symmetry and comprises a carbon to carbon bond joining a chiral carbon atom to a carbon atom of a cyclopentadiene ring that is non-symmetrically substituted. Examples of such compounds include compounds of formula (I) wherein, X1 and X2 are, independently, groups which are removable during a chemical reaction; M is titanium, zirconium or hafnium; and R1-8,11 are as specified in the description.(FR) L'invention porte sur un composé organométallique, chiral, qui, à un niveau moléculaire, est asymétrique en C2 et comporte une liaison carbone-carbone liant un atome chiral de carbone à un atome de carbone d'un anneau de cyclopentadiène substitué de manière asymétrique. Au nombre de ces composés figurent des composés de la formule (I) dans laquelle X1 et X2 représentent, de façon indépendante, des groupes remplaçables au cours d'une réaction chimique; M est titane, zirconium ou hafnium et où R1-8,11 correspond à la définition donnée dans la description.