Magnesium triflate [Mg(OTf)2] a highly stable, non-hygroscopic and a recyclable catalyst for the high yielding preparation of diethyl α-trimethylsilyloxyphosphonates from diethyl α-hydroxyphosphonates by HMDS under solventless conditions
and convenient procedure for the easy conversion of various α-hydroxyphosphonates to α-trimethylsilyloxyphosphonates under mild conditions with HMDS in the presence of a catalytic amount of magnesium triflate as a highly stable and a non-hygroscopic recyclable catalyst in neat conditions is described. In order to show the general applicability of this method, we have also applied this procedure successfully
Aluminium Triflate [Al(OTf)<sub>3</sub>] as a Recyclable Catalyst for the Conversion of α-Hydroxyphosphonates, Alcohols and Phenols to Their Corresponding O-Silylated Products with Hexamethyldisilazane (HMDS)
Al(OTf)3 as a recyclable catalyst conducts the efficient conversion of various types of α-hydroxyphosphonates to their corresponding α-trimethysilyloxyphosphonates with HMDS in the absence of solvent at room temperature. The general applicability of the catalyst under solvent-free conditions is demonstrated by applying it for the successful silylation of alcohols and phenols with HMDS in high yields.
Pyrazinoic Acid Esters with Broad Spectrum in Vitro Antimycobacterial Activity
作者:Michael H. Cynamon、Rayomand Gimi、Ferenc Gyenes、Cindy A. Sharpe、Kathryn E. Bergmann、Hye Jung Han、Livia B. Gregor、Radha Rapolu、Gregorio Luciano、John T. Welch
DOI:10.1021/jm00020a003
日期:1995.9
A series of substituted pyrazinoicacidesters has been prepared and examined for their in vitro activity against Mycobacterium avium and Mycobacterium kansasii as well as Mycobacterium tuberculosis. Modification of both the pyrazine nucleus and the ester functionality have been very successful in expanding the activity of pyrazinamide to include M. avium and M. kansasii, organisms normally not susceptible
Transition-metal chloride mediated addition reaction of diorganomagnesium to easily enolizable ketones
作者:Mutsumi Sada、Seijiro Matsubara
DOI:10.1016/j.tet.2011.02.009
日期:2011.4
is difficult to perform with Grignardreagent (RMgX) or with diorganomagnesium (R2Mg), because a deprotonation to form a magnesium enolate occurs predominantly. To avoid the prior enolization, a complex reagent of a transition-metal salt and R2Mg was examined: A combination of R2Mg with iron(II) chloride (FeCl2) or ytterbium(III) chloride (YbCl3) gave a complex reagent that can realize a nucleophilic
Methyl group migration in the reactions of alkynyltrialkylborates
作者:Andrew Pelter、Robert A. Drake
DOI:10.1016/s0040-4039(00)80450-5
日期:1988.1
It is shown that the methyl group cannot be used as a cheap, non-migrating group in the reactions of alkynyltrialkylborates with electrophiles. However, trimethylborane can be used as a methylboronating agent for alkynes, given the right choice of solvent, and this may be of use in terpene synthesis.