Reactions of thiobenzoylketene S,N-acetals with silyl enol ethers of cyclic ketones in the presence of desilylating reagents: formation and desulfurization of thienolactams
作者:Jong Seok Lee、Dong Joon Lee、Bo Sung Kim、Kyongtae Kim
DOI:10.1039/b102922n
日期:2001.11.1
Medium-sized thienolactams can be directly prepared from thiobenzoylketene S,N-acetals, Hg(OAc)2, and silyl enol ethers of cyclic ketones, and either TBAF or TASF. However, by adding either water or alcohol to the foregoing mixture, 3-methylamino-5-phenylthiophenes, in which the ω-position of long-chain alkanoic acids and alkanoic esters are bonded to C-2 of the thiophene ring, can be obtained albeit in low yields. Sequential treatment of the thienolactams with Raney nickel and Adam's catalyst results in completely reductive desulfurization of thienolactam molecules.
The synthesis of A- and B-ring fluorinated analogues of cholesterol
作者:Michael G. Thomas、Colin J. Suckling、Andrew R. Pitt、Keith E. Suckling
DOI:10.1039/a904826j
日期:——
The synthesis of a number of mono- and difluorinated steroids with the potential to act as probes of the metabolism of cholesterol is described. 2α-Fluorocholestan-3-one 7, 4-fluorocholest-5-en-3-one 11 and 6-fluorocholest-4-en-3-one 12 were synthesised from the appropriate silyl enol ethers using 1-fluoropyridinium triflate, and subsequently reduced to the corresponding alcohols, 8, 13 and 14 respectively