65730-15-6Relevant academic research and scientific papers
In situ generated bulky palladium hydride complexes as catalysts for the efficient isomerization of olefins. Selective transformation of terminal alkenes to 2-alkenes
Gauthier, Delphine,Lindhardt, Anders T.,Olsen, Esben P. K.,Overgaard, Jacob,Skrydstrup, Troels
supporting information; experimental part, p. 7998 - 8009 (2010/08/04)
Application of an in situ generated bulky palladium(II) hydride catalyst obtained from a 1:1:1 mixture of Pd(dba)2, P(tBu)3, and isobutyryl chloride provides an efficient protocol for the isomerization and migration of a variety of olefins. In addition to the isomerization of (Z)- to (E)-olefins, the conjugative migration of allylbenzenes, allyl ethers, and amines was effectively achieved in near-quantitative yields and with excellent functional group tolerance. Catalyst loadings in the range of 0.5-1.0 mol % were typically applied, but even loadings as low as 0.25 mol % could be achieved when the reactions were performed under neat conditions. More interestingly, the investigated catalyst proved to be selective for converting terminal alkenes to 2-alkenes. This one-carbon migration process for monosubstituted olefins provides an alternative catalyst, which bridges the gap between the allylation and propenylation/vinylation protocols. Several substrates, including homoallylic alcohols and amines, were selectively transformed into their corresponding 2-alkenes, and examples using enantiomerically enriched substrates provided products without epimerization at the allylic stereogenic carbon centers. Finally, some mechanistic investigations were undertaken to understand the nature of the active in situ generated Pd-H catalyst. These studies revealed that the catalytic system is highly dependent on the large steric demand of the P(tBu)3 ligand. The use of an alternative ligand, cataCXium PinCy, also proved effective for generating an active catalyst, and it was demonstrated in some cases to display better selectivity for the one-carbon shifts of terminal olefins. A possible intermediate involved in the preparation of the active catalyst was characterized by its single-crystal X-ray structure, which revealed a monomeric tricoordinated palladium(II) acyl complex, bearing a chloride ligand.
Protected glycosides and disaccharides of 2-amino-2-deoxy-D-glucopyranose by ferric chloride-catalyzed coupling.
Kiso,Anderson
, p. 309 - 323 (2007/10/02)
The ferric chloride-catalyzed glycosylation of hydroxy compounds by protected 2-acylamino-2-deoxy-beta-D-glucopyranose 1-acetates is described. In addition to known glycosides from the reaction of alcohols with 2-acetamido-1,3,4,6-tetra-O-acetyl-2-deoxy-beta-D-glucopyranose (3), ally (and other alkyl) beta-glycosides were obtained from the N-benzoyl, N-phenoxyacetyl, N-methoxyacetyl, N-chloroacetyl, and N-phthaloyl congeners of 3. The latter compounds, except for the N-phthaloyl derivative, gave oxazolines in the absence of an alcoholic reactant. Compound 3 and the related N-benzoyl, N-chloroacetyl, N-acetyl-3,4,6-tri-O-benzyl, and N-acetyl-4-O-acetyl-3,6-di-O-benzyl derivatives were coupled to one or more protected sugars to form protected, beta-linked disaccharides. Coupling at the 6-positions of acceptors proceeded smoothly and gave 67-80% yields. For successful coupling at positions 3 and 4, long reaction times and multiple additions of glycosyl donor were required, and yields ranged from 60% to as low as 30%. 1,3,4,6-Tetra-O-acetyl-2-(chloroacetamido)-2-deoxy-beta-D- glucopyranose appeared to be the most reactive glycosyl donor in this series. The reaction of 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-alpha-D-glucopyrano)[2,1- d]-2-oxazoline (derived from 3) with allyl alcohol was catalyzed by ferric chloride, and oxazolines were detected as intermediates in some of the glycosylations of protected sugars.
Conversion of the N-Benzylacetamido Group into the Acetamido Group by Autoxidation in Potassium t-Butoxide-Dimethyl Sulphoxide
Gigg, Roy,Conant, Robert
, p. 465 - 466 (2007/10/02)
The N-benzylacetamido group is rapidly converted into the acetamido group at 20 deg C by the action of molecular oxygen in a solution of potassium t-butoxide in dimethyl sulphoxide and a general route to acetylated amines by the alkylation of N-benzylacet
O-BENZYLATED OXAZOLINE DERIVATIVES OF 2-ACETAMIDO-2-DEOXY-D-GLUCOPYRANOSE FROM 1-PROPENYL GLYCOSIDES. SYNTHESIS OF THE PROPENYL GLYCOSIDES AND THEIR DIRECT CYCLIZATION
Nashed, Mina A.,Slife, Charles W.,Kiso, Makoto,Anderson, Laurens
, p. 237 - 252 (2007/10/02)
1-Propenyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α- and -β-D-glucopyranosides (3α, 3β) were obtained by the successive isomerization and acetylation of the known allyl glycosides 1α and 1β.The allyl glycosides were also converted, via their benzylidene 4
