Preparation and Properties of Trimethylsilyl Ethers and Related Compounds

Synthesis and antibacterial evaluation of 6-azapyrimidines with α-methylene-γ-(4-substituted phenyl)-γ-butyrolactone pharmacophores

“…Silylation of 6-substituted 1,2,4-triazine-3,5(2H,4H)-diones (1) and (2) according to Langer et al (1958) with hexamethyldisilazane (HMDS) and a catalytic amount of chlorotrimethylsilane furnished silylated intermediates, which were used for the condensation with 4-substituted-2-bromoacetophenones in dry acetonitrile. Compound 3 and 4 were then reacted with ethyl a-(bromomethyl)acrylate and zinc powder in dry tetrahydrofuran (Reformatsky-type reaction) to afford 5 and 6 in fairly good yields.…”

Chemical derivatization of Athabasca oil sand asphaltene for analysis of hydroxyl and carboxyl groups via nuclear magnetic resonance spectroscopy

“…80 8Ci n nitrogen for ca. 1 h [28,30]. The solvent and reagent were removed in a stream of nitrogen gas at ca.…”

“…8) can be hydrolyzed in the presence of water and acid, resulting in trimethylsilanol which can then form hexamethyldisiloxane. In fact, HCl is generated by trimethylchlorosilane used to catalyze the TMS reaction [28]. Precipitation of ammonium chloride and pyridinium hydrochloride in the CDCl 3 solution can subsequently contribute to line broadening of the NMR peaks.…”

Sulfonated Ordered Nanoporous Carbon (CMK-5-SO3H) as an Efficient and Highly Recyclable Catalyst for the Silylation of Alcohols and Phenols with Hexamethyldisilazane (HMDS)

“…As it is widely known, silyl ethers are resistant to oxidation, have a good stability for most non-acidic reagents and are easily deprotected to provide the free alcohols [3]. Generally, the formation of silyl ethers carried out by treatment of parent alcohols with silyl halides or silyl triflates in the presence of stoichiometric amounts of a base [4][5][6], Li 2 S [7], and occasionally with a nonionic super base catalyst [8][9][10][11].…”

“…Even though the handling of this reagent is easy, its main drawback is its poor silylating power which needs forceful conditions and long reaction times in many instances [12]. Therefore, a variety of catalysts have been developed for activation of this reagent, such as sulfuric acid [1,2], (CH 3 ) 3 SiCl [13], sulfonic acids [14], K-10 montmorilonite [15,16], iodine [17], tungstophosphoric acid (H 3 PW 12 O 40 ) [18], LiClO 4 [19], Mg(OTf) 2 [20], CuSO 4 Á5H 2 O [21], TBBDA, and PBBS [22], [PdCl(g 3 -C 3 H 5 )] 2 -PPh 3 [23], MgBr 2 ÁOEt 2 [24], InBr 3 [25], LaCl 3 [26], HReO 4 [27], silica supported perchloric acid [28], trichloroisocyanuric acid [29], Fe(F 3 CCO 2 ) 3 [30], Zr(OTf) 2 [31], Bi(OTf) 3 [32], and TiCl 2 (OTf)-SiO 2 [33]. Although several of these procedures are useful, some of them suffer from the use of homogenous and often corrosive catalyst, tedious workup and long reaction times.…”