Here, we describe one simple Ir/hydrosilane catalytic system for chemoselective isomerization of 2-substituted allylic ethers. This facile strategy shows high efficiency towards a variety of substrates, including derivatives from bioactive molecules. The substituent at the α position of the olefins is supposed to be critical in retarding the alkene hydrosilylation process and leading the reaction to
are readily cleaved by metallic magnesium in absolute tetrahydrofuran forming allylmagnesium naphtholates in excellent yields. The cleavage of 2-methylallyl β-naphthyl ether, on the other hand, proceeds slowly giving good yields only after long reaction times. With 2-methylallyl α-naphthyl ether yields are low even after very long reaction times. Wurtz-type coupling products are never observed.
Transition Metal Catalyzed Oxidation; 8: 4-Allyl-Substituted 1,2-Naphthoquinones via Tandem ortho-Phenol Oxygenation and Oxy-Cope Rearrangement
作者:Karsten Krohn、Sven Bernhard
DOI:10.1055/s-1996-4281
日期:1996.6
4-Allyl-1,2-naphthoquinones 3a-3d are prepared in one operation from 2-allyl-1-naphthols 2a-2d involving tandem zirconium-catalyzed tert-butyl hydroperoxide (TBHP) oxidation and oxy-Cope rearrangement.
Scaling-Out Pharmaceutical Reactions in an Automated Stop-Flow Microwave Reactor
作者:Jonathan D. Moseley、Emily K. Woodman
DOI:10.1021/op800091p
日期:2008.9.19
Six pharmaceutically relevant reactions were assessed for scale-out in an automated stop-flow microwave reactor. Daily throughputs of between 50 and 250 g were achieved at typical reaction concentrations; for more concentrated reactions, or with 24 h processing, productivity of 0.5-1.5 kg per day was achievable. This study confirms that the stop-flow approach in combination with rapid microwave heating can be equivalent to conventional continuous flow technology with comparable productivities.