An efficient method for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS) catalyzed by aluminum tris(dihydrogen phosphate) under solvent-free and ambient conditions
A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS), using Al(H2PO4)3 as a recyclable heterogeneous catalyst at room temperature in a few minutes with excellent yields under solvent-free conditions is described.Key words: trimethylsilylation
The regioselective synthesis of isomeric 5(3)‐aminomethyl‐3(5)‐phenyl isoxazoles using different methods is described. Spectroscopic data, especially mass spectrometric fragmentation, were used to identify and characterize the regioisomers. The muscarinicactivity of these isoxazoles was assayed on isolated guinea‐pig ileum and atria as well as on isolated rabbit vas deferens.
Alumina Perchloric Acid (Al<sub><b><i>2</i></b></sub>O<sub><b><i>3</i></b></sub>-HClO<sub><b><i>4</i></b></sub>) as an Efficient Heterogeneous Catalyst for Modified Preparation of Trimethylsilyl Ethers
for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS) using alumina perchloric acid (Al 2 O 3 -HClO 4 ) as recyclable heterogeneous catalyst in excellent yields with short reaction times (3−65 min) under ambient conditions is described.
Asymmetric synthesis using chirally modified borohydrides. Part 3. Enantioselective reduction of ketones and oxime ethers with reagents prepared from borane and chiral amino alcohols
The asymmetric reduction of aromatic and aliphatic ketones, halogeno ketones, hydroxy ketones, keto esters, and ketone oxime ethers with reagents prepared from borane and chiral amino alcohols has been investigated. When α,α-diphenyl β-amino alcohols, such as (2S,3R)-(–)-2-amino-3-methyl-1,1 -diphenylpentanol (2d), were used as a chiral auxiliary, very high enantioselectivities (ca. 90 % e.e.) were
A New Synthesis of Oxime Derivatives from Carbonyl Compounds and<i>N,O</i>-Bis(trimethylsilyl)hydroxylamine
作者:Robert V. Hoffman、Gregory A. Buntain
DOI:10.1055/s-1987-28092
日期:——
Reaction of a series of aldehydes and ketones with the potassium salt of N,O-bis(trimethylsilyl)hydroxylamine (2) gave high yields of the corresponding oximate anion 5. This anion, formed in a Peterson-type reaction, could be protonated to the oxime 7 or trapped in situ with a variety of electrophiles to give O-substituted oxime derivatives.8