Regio- and stereoselective 6- exo - trig radical cyclisations onto chiral perhydro-1,3-benzoxazines: synthesis of enantiopure 3-alkylpiperidines
摘要:
Enantiopure 3-alkyl substituted piperidines are prepared by diastereoselective 6-exo-trig cyclisation of perhydro-1,3-benzoxazines derived from (-)-(8)-amino menthol. The diastereoselective cyclisation is promoted by tributyltin hydride, and the competitive 1,5-hydrogen migration depends on the position of the acceptor double bond and the radical site. (C) 2000 Elsevier Science Ltd. All rights reserved.
The geometry of the carbanionic moiety influences the non-induced diastereoselectivity of the [2,3]-Wittig rearrangement of lithiated diallyl ethers
作者:Dirk Goeppel、Ingo Münster、Reinhard Brückner
DOI:10.1016/s0040-4020(01)90391-6
日期:1994.3
diallyl ethers 10, from the vinylogous O,S-acetals 13, and from the O,S-acetals 14 by treatment with nBuLi (in the case of 10) or with lithium naphthalenide (in the case of 13 and 14). [2,3]-Wittig rearrangements ensued whose syn,anti-selectivity was studied.
Zn/RuCl<sub>3</sub>-Promoted Cleavage of Diselenides: An Efficient Michael Addition of Zinc Selenolates to Conjugated Alkenes in Aqueous Media
作者:Barahman Movassagh、Ameneh Tatar
DOI:10.1055/s-2007-984495
日期:2007.7
simple and highly efficient one-pot route to β-selenocarbonyl compounds and nitriles has been developed by Zn/RuCl 3 -catalyzed cleavage of diselenides and subsequent Michael addition of zinc selenolates to conjugated alkenes in aqueousmedia.
A Simple Zinc-Mediated Method for Selenium Addition to Michael Acceptors
作者:Francesca Giulia Nacca、Bonifacio Monti、Eder João Lenardão、Paul Evans、Claudio Santi
DOI:10.3390/molecules25092018
日期:——
biphasic Zn/HCl-based reducing system. Alkenes with a variety of electron-withdrawing groups were investigated in order to gauge the scope and limitations of the process. Results demonstrated that the addition to acyclic α,β-unsaturated ketones, aldehydes, esters amides, and acids was effectively achieved and that alkyl substituents at the reactive β-centre can be accommodated. Similarly, cyclic enones
In the presence of catalytic to stoichiometric amounts of trimethylsilyl triflate, 1:1:1 mixtures of silyl ethers, phenyl(trimethylsilyl)sulfide, and aldehydes give O,S-acetals in fair to good yields.
Exploring synthetic avenues for the effective synthesis of selenium- and tellurium-containing multifunctional redox agents
作者:Susanne Mecklenburg、Saad Shaaban、Lalla A. Ba、Torsten Burkholz、Thomas Schneider、Britta Diesel、Alexandra K. Kiemer、Anne Röseler、Katja Becker、Jörg Reichrath、Alexandra Stark、Wolfgang Tilgen、Muhammad Abbas、Ludger A. Wessjohann、Florenz Sasse、Claus Jacob
DOI:10.1039/b907831b
日期:——
Various human illnesses, including several types of cancer and infectious diseases, are related to changes in the cellular redox homeostasis. During the last decade, several approaches have been explored which employ such disturbed redox balances for the benefit of therapy. Compounds able to modulate the intracellular redox state of cells have been developed, which effectively, yet also selectively, appear to kill cancer cells and a range of pathogenic microorganisms. Among the various agents employed, certain redox catalysts have shown considerable promise since they are non-toxic on their own yet develop an effective, often selective cytotoxicity in the presence of the ‘correct’ intracellular redox partners. Aminoalkylation, amide coupling and multicomponent reactions are suitable synthetic methods to generate a vast number of such multifunctional catalysts, which are chemically diverse and, depending on their structure, exhibit various interesting biological activities.