Asymmetric cyanosilylation of alkynyl ketones with the catalyst systems consisting of amino acid/2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP)/ruthenium(II) complex and lithium phenoxide (Ru⋅Li cat.) was studied. The reaction was conducted in tert‐butyl methyl ether (TBME) at −78 °C with a substrate‐to‐catalyst molar ratio (S/C) as high as 2000. A series of simple and functionalized ketones was converted
作者:M. Mark midland、Alfonso tramontano、Aleksander kazubski、Richard S. graham、David J.S. tsai、Daniel B. cardin
DOI:10.1016/s0040-4020(01)82422-4
日期:1984.1
Propargyl ketones are readily reduced by the asymmetric reducing agent B-3-pinanyl-9- borabicyclo[3.3.1]-nonane (Alpine-borane). The reagent prepared from (+)-α-pinene and 9-BBN provides the R enantiomer while the S enantiomer can be obtained from (-)-α-pinene. Alternatively the S enantiomer can be prepared from the reagent derived from 9-BBN and the benzyl ether of nopol (6,6-dimethyl-bicyclo[3.11
2-Allyl-1,2,3-triazoles were prepared by the palladium-catalyzed three component coupling (TCC) reaction of alkynes, allyl methyl carbonate and trimethylsilyl azide. A π-allylpalladium azide complex, which undergoes the 1,3-dipolar cycloaddition with alkynes, is proposed as a key intermediate in the TCC reaction.
Propargyl aza-Claisenrearrangement of 4-propargylaminoisoxazoles 1 proceeded in the presence of cationic gold(I) catalysts to give 4-amino-5-allenylisoxazoles 2 in good to high yields. The silyl group at the terminal alkyne and a cationic gold(I) catalyst bearing a sterically bulky ligand are essential for the generation of isolable allene intermediates. The N-protection of the generated 4-amino-5-allenylisoxazoles
Improved highly efficient synthesis of α,β-acetylenic ketones. Nature of the intermediate from the reaction of lithium acetylide with boron trifluoride etherate
作者:Herbert C. Brown、Uday S. Racherla、Shankar M. Singh、Richard B. Wetherill
DOI:10.1016/s0040-4039(01)81192-8
日期:1984.1
A wide variety of α,β-acetylenic ketones were synthesized in very high yields via an exceptionally facile intermolecular reaction of lithium alkynyltrifluoroborates and carboxylic acid anhydrides.