Cholane Derivatives with Potential Ligating Groups at the 3‐ and 24‐Positions
作者:Sudershan Reddy Gondi、David Y. Son
DOI:10.1080/00397910500521803
日期:2006.6.1
lithocholic acid, a number of new cholane derivatives have been prepared consisting of the same or different electron‐donor groups at the 3‐ and 24‐positions. Yields ranged from good to excellent. The donor groups were chosen on the basis of their known ability to coordinate to transition‐metal ions and include pyridyl, 1,3‐dithiolanyl, phenylthioether, and oxime ether groups.
Photoexcited Palladium-Initiated Remote Desaturation of <i>N</i>-Alkoxypyridinium Salts
作者:Weiwei Jin、Shouyun Yu
DOI:10.1021/acs.joc.2c02036
日期:2022.11.4
1,5-Hydrogen atom transfer (HAT) is an effective strategy to achieve remote desaturation of nonfunctionalized alkanes. Herein, we report a photoinduced remote desaturation reaction of N-alkoxypyridinium salts, which serve as alkoxyl radical precursors. Mechanistic studies show that a single electrontransferbetween the excited palladium complex and a N-alkoxypyridinium salt initiates a radical chain
作者:Kihira Kenji、Mikami Takahiro、Ikawa Seiichiro、Okamoto Akira、Yoshii Michiko、Miki Shigeo、Erwin H. Mosbach、Hoshita Takahiko
DOI:10.1016/0039-128x(92)90008-w
日期:1992.4
Sulfonate analogs of C23 and C24 bile acids were synthesized from norcholic, norchenodeoxycholic, norursodeoxycholic, nordeoxycholic, norhyodeoxycholic, cholic, deoxycholic, hyodeoxycholic, and lithocholic acids. The principal reactions used were (1) reduction of the bile acids with NaBH4 to the corresponding bile alcohols, (2) selective tosylation of the terminal hydroxyl group, (3) iodination of the tosyl esters with NaI, and (4) treatment of the iodides with Na2SO3 to form the sulfonate analogs of the bile acids. The sulfonate analogs showed polarity similar to that of taurine-conjugated bile acids on thin-layer chromatography. The carbon 13 nuclear magnetic resonance spectral data for the sulfonate analogs were tabulated.
Transamination Reactions with Multiple Turnovers Catalyzed by Hydrophobic Pyridoxamine Cofactors in the Presence of Polyethylenimine Polymers
Pyridoxamines carrying hydrophobic side chains reversibly bind into the hydrophobic core of polyethylenimines and transaminate ketoacids to amino acids with as much as a 725000-fold rate acceleration. Turnover catalysis was achieved by sacrificial oxidative decarboxylation of C-substituted amino acids, which reconverted the pyridoxals to pyridoxamines.
Nahar, Lutfun; Turner, Alan B., Journal of Chemical Research, 2004, # 11, p. 747 - 749