442904-02-1Relevant articles and documents
Gold(I)-Catalyzed Cyclization-3-Aza-Cope-Mannich Cascade and Its Application to the Synthesis of Cephalotaxine
Sakai, Takeo,Okumura, Chise,Futamura, Masatoshi,Noda, Naotaka,Nagae, Akari,Kitamoto, Chiharu,Kamiya, Madoka,Mori, Yuji
supporting information, p. 4391 - 4395 (2021/05/26)
The discovery of a new gold(I)-catalyzed cascade reaction involving cyclization onto a vinylammonium, 3-aza-Cope rearrangement, and Mannich cyclization is reported. A variety of fused nitrogen heterocycles were prepared from simple cyclic tertiary amines using 1-5 mol % of a AuCl(PPh3)/Ag[C5(CN)5] cocatalyst system. The developed reaction was used in a study aimed at synthesizing cephalotaxine. A five-step operation from norhydrastinine provided demethylcephalotaxinone in 39.1% overall yield, which was transformed to (-)-cephalotaxine in two steps.
An unusual access to medium sized cycloalkynes by a new goId(I)-catalysed cycloisomerisation of diynes
Odabachian, Yann,Le Goff, Xavier F.,Gagosz, Fabien
supporting information; scheme or table, p. 8966 - 8970 (2010/04/25)
A study was conducted to demonstrate efficient cycloisomerization of a series of 1,9- and 1,10-diynes into medium sized cycloalkynes by a gold-catalyzed alkyne-alkyne coupling. The reaction was performed using 4 mol% of gold complex in CD2Cl2 at room temperature and was monitored by using 1H NMR spectroscopy. The reaction of analogous diyne substrate was more rapid and a complete conversion was observed after 40 hours at room temperature. The cycloalkyne was isolated as a solid in 95% yield from which single crystals suitable for X-ray crystal structure determination was obtained. A rapid screening of catalysts and experimental conditions was undertaken to optimize the formation of cycloalkyne. A mechanistic proposal was also introduced for the cycloisomerization of diynes into cycloalkynes on the basis of the experimental observations.
Intramolecular palladium-catalyzed cyclization of alkenylboronate prepared from hydroboration of terminal acetylene and its application to the stereoselective synthesis of (E)-doxepin
Xue, Cuihua,Kung, Shi-Hao,Wu, Jian-Zhung,Luo, Fen-Tair
, p. 248 - 254 (2008/09/16)
The hydroboration of 2-[(2-ethynylphenyl)methoxy]-1-iodobenzene with bis(pinacolato)diboron in the presence of palladium catalyst and followed by consecutive oxidative addition, cis-cyclocarbopalladation, and cis-β-elimination could give highly stereosele
Studies on tellurium-containing heterocycles. Part 18. Preparation and structure of 2-benzotelluropyrylium salts and 2-benzoselenopyrylium salts
Sashida, Haruki,Ohyanagi, Kazuo,Minoura, Mao,Akiba, Kin-Ya
, p. 606 - 612 (2007/10/03)
The regioselective and stereospecific intramolecular ring closure reactions of o-ethynylbenzyl tellurols 5A and o-ethynylbenzyl selenols 5B, which were readily generated by the reaction of the o-ethynylbenzyl bromides 4 with sodium hydrogen telluride (NaH
Intramolecular aminopalladation and cross coupling of acetylenic amines
Luo, Fen-Tair,Wang, Ren-Tzong
, p. 6835 - 6838 (2007/10/02)
Stereodefined 2-alkylidene-pyrrolidines and -piperidine were synthesized by treatment of an acetylenic amines with n-BuLi followed by addition of catalytic amount of Pd(OAc)2 and PPh3 in THF and 3 equiv of an organic halide.
