Tris(3,6-dioxaheptyl)amine: A superior complexing agent for dissolving metal reactions
作者:Ajay K. Bose、Pietro Mangiaracina
DOI:10.1016/s0040-4039(00)95452-2
日期:1987.1
Commercially available tris(3,6-dioxaheptyl)amine (TDA-1) is an effective phase transfer catalyst for reactions with sodium-potassium alloy in tetrahydrofuran. Deoxygenation of acetates, dehalogenation, and hydrolysis of tosylates and mesylates proceed in high yield. The use of a deuterated alcohol during deoxygenation reactions leads to site-specific deuteration.
Practical Synthesis of 3β-Amino-5-cholestene and Related 3β-Halides Involving <i>i</i>-Steroid and Retro-<i>i</i>-Steroid Rearrangements
作者:Qi Sun、Sutang Cai、Blake R. Peterson
DOI:10.1021/ol802343z
日期:2009.2.5
method for the stereoselective preparation of 3β-amino-5-cholestene, 3β-chloro-5-cholestene, 3β-bromo-5-cholestene, and 3β-iodo-5-cholestene from inexpensive cholesterol. A sequential i-steroid/retro-i-steroid rearrangement promoted by boron trifluoride etherate and trimethylsilyl azide converted cholest-5-en-3β-ol methanesulfonate to 3β-azido-cholest-5-ene with retention of configuration in 93% yield
Iron(III)-Catalyzed Halogenations by Substitution of Sulfonate Esters
作者:Nuria Ortega、Andrés Feher-Voelger、Margarita Brovetto、Juan I. Padrón、Victor S. Martín、Tomás Martín
DOI:10.1002/adsc.201000740
日期:2011.4.18
A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary
Efficient method for inversion of secondary alcohols by reaction of chloromethanesulfonates with cesium acetate
作者:Takeshi Shimizu、Sayoko Hiranuma、Tadashi Nakata
DOI:10.1016/0040-4039(96)01333-0
日期:1996.8
Inversion of a variety of secondaryalcohols using the (chloromethylsulfonyl)oxy group as a favorable leaving group with cesiumacetate in the presence of 18-crown-6 has been performed to give the inverted acetates in high yields.
Group 4 metallocene complexes bearing cholestanol-derived substituents at the Cp-rings— their synthesis and use in propene polymerization catalysis
作者:Gerhard Erker、Christoph Mollenkopf
DOI:10.1016/0022-328x(94)87161-2
日期:1994.12
corresponding fulvene, methyl lithium was added and deprotonation and addition to ZrCl4(THF)2 furnished bis[η5-(3β-methyl- 5α-cholestan-3α-yl)cyclopentadienyl]zirconium dichloride (11b). Treatment of the chiral Cp-substituted zirconocene dichlorides with a large excess of methylalumoxane gave homogeneous Ziegler catalysts. Propenepolymerization proceeded with overall stereochemical chain end control to