Silver(I)-Catalyzed Deprotection of p-Methoxybenzyl Ethers: A Mild and Chemoselective Method
摘要:
The p-methoxybenzyl protecting group (PMB) on various alcohols and an acid was efficiently and selectively, cleaved by the action of a catalytic amount of silver(I) hexafluoroantimonate combined with 0.5 equiv of 1,3,5-trimethoxybenzene in dichloromethane at 40 degrees C.
Catalytic hydrofluorination of olefins using a cobalt catalyst was developed. The exclusive Markovnikov selectivity, functional group tolerance, and scalability of this reaction make it an attractive protocol for the hydrofluorination of olefins. A preliminary mechanistic experiment showed the involvement of a radical intermediate.
A unique Markovnikov hydroalkoxylation of unactivated olefins with a cobalt complex, silane, and N-fluoropyridinium salt is reported. Further optimization of reaction conditions yielded high functional group tolerance and versatility of alcoholic solvent employed, including methanol, i-propanol, and t-butanol. Use of trifluorotoluene as a solvent made the use of alcohol in stoichiometric amount possible. Mechanistic insight into this novel catalytic system is also discussed. Experimental results suggest that catalysis involves both carbon radical and carbocation intermediates.
Conversion of Epoxides to 1,3-Dioxolanes Catalyzed by Tin(II) Chloride
作者:James R. Vyvyan、Jennifer A. Meyer、Korin D. Meyer
DOI:10.1021/jo035112y
日期:2003.11.1
Anhydrous tin(II) chloride is an efficient catalyst for the reaction of epoxides with acetone to prepare 2,2-dimethyl-1,3-dioxolanes (acetonides) in good to excellent yields. Mono-, di-, and trisubstituted epoxides participate equally well in this diastereospecific reaction. The use of single enantiomer epoxides under the reported conditions results in significant erosion of optical activity.
Identification of Target Protein for Batzelladines as CD4