- A convenient synthesis of 2-phenylglycerol
-
1,3-Dihydroxyacetone dimer is treated with trimethylsilyl chloride and triethylamine in dichloromethane to provide monomeric ketone having both of its alcohols protected as their di-TMS ethers. The latter is added to phenylmagnesium bromide in ether at -78°C. Work-up by treatment with aqueous ammonium chloride followed by 2 N HCl provides 2-phenylglycerol in 70% yield.
- Klis,Erhardt
-
p. 4027 - 4038
(2007/10/03)
-
- Dehomologation of Aldehydes via Oxidative Cleavage of Silyl Enol Ethers with Aqueous Hydrogen Peroxide Catalyzed by Cetylpyridinium Peroxotungstophosphate under Two-Phase Conditions
-
Dehomologation of aldehydes has been first successfully achieved via oxidative cleavage of silyl enol ethers, derived from aldehydes and trimethylchlorosilane, using aqueous hydrogen peroxide in the presence of a catalytic amount of peroxotungstophophate (PCWP) under phase-transfer conditions. For instance, the oxidation of 1-[(trimethylsilyl)oxy]-1-octene resulting from octanal and Me3SiCl with 35% H2O2 catalyzed by PCWP in dichloromethane at room temperature afforded the one-carbon shorter aldehyde, heptanal, in 79% yield. A variety of silyl enol ethers were also converted into one-carbon shorter aldehydes in good yields. The oxidation under homogeneous conditions using tert-butyl alcohol gave hydrolysis products such as 2-oxooctanol and octanal. It is of interest that [1-(trimethylsilyl)oxy]-1,10-undecadiene involving an enol moiety and a terminal double bond afforded exclusively 9-decenal, in which the enol moiety was selectively oxidized. A plausible reaction path for the oxidative cleavage of silyl enol ethers by the present system has been suggested from the oxidation results of α-[(trimethylsilyl)oxy]styrene.
- Sakaguchi, Satoshi,Yamamoto, Yumiko,Sugimoto, Takuma,Yamamoto, Hiroyo,Ishii, Yasutaka
-
p. 5954 - 5957
(2007/10/03)
-
- Reactivity and selectivity in the oxidation of styrene derivatives. V. studies on the oxidation of α-substituted styrenes
-
The liquid phase oxidation of α-phenyl-1a, α-trimethylsilyloxy 1b, α-cyclopropyl-1c, α-trifluoromethyl-1d styrene, and styrene 1e with oxygen in chlorobenzene and cumene solution in the temperature range 55-125°C was investigated. The product yields were determined gaschromatographically. The epoxide selectivity increases up to 90°C with increasing temperature. The epoxides of 1a and 1c rearrange at higher temperatures, therefore their yield decreases. The relative chain propagation constants (kpC=C) were determined by competitive oxidations of cumene. WILEY-VCH Verlag GmbH, 1999.
- Suprun
-
-
- Oxygenation of Silyl Enol Ethers and Silyl Ketene Acetals with Molecular Oxygen and Aldehyde Catalyzed by Nickel(II) Complex. A Convenient Method for the Preparation of α-Hydroxy Carbonyl Compounds
-
In the presence of a catalytic amount of nickel(II) complex, silyl enol ethers and silyl ketene acetals are smoothly oxygenated by the combined use of molecular oxygen and aldehyde to afford α-siloxy carbonyl compounds via possible intermediates, siloxy epoxides.And on treatment of the α-siloxy carbonyl compounds with potassium fluoride α-hydroxy carbonyl compounds are obtained in good to high yields.
- Takai, Toshihiro,Yamada, Tohru,Rhode, Oliver,Mukaiyama, Teruaki
-
p. 281 - 284
(2007/10/02)
-
- 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, 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. 90percent e.e.) were obtained in the reduction of various ketones and oxime ethers.
- Itsuno, Shinichi,Nakano, Michio,Miyazaki, Koji,Masuda, Hirofumi,Ito, Koichi,et al.
-
p. 2039 - 2044
(2007/10/02)
-
- Induction asymetrique. V. Determination des configurations relatives de γ-amino β-hydroxyesters diastereoisomeres, obtenus par la reaction de Reformatsky
-
Addition of various Reformatsky reagents (R1-CHZnBr-CO2CH3) to three aromatic α-aminocetones yields mixtures of threo and erythro diastereomeric γ-amino β-hydroxyesters.The relative configurations of the first terms of eac
- Lucas, Marc,Guette, Jean-Paul
-
p. 701 - 720
(2007/10/02)
-