62559-36-8Relevant academic research and scientific papers
Acceleration of hetero-Michael reaction by symmetrical pentacyclic guanidines
Nagasawa, Kazuo,Georgieva, Angelina,Takahashi, Hiroki,Nakata, Tadashi
, p. 8959 - 8964 (2007/10/03)
Symmetrical pentacyclic guanidines 1a-c and 2 which contain the core skeleton of 13,14,15-isocrmbescidine 800, have been synthesized. In the presence of catalytic amounts of these guanidines 1, the reaction rate of the conjugate addition of pyrrolidine (9) to γ-crotonolactone (10) could be enhanced depending upon the size of the cavities and substituents on tetrahydropyran rings of 1 and 2.
Stereoselective radical aryl migration from silicon to carbon
Amrein, Stephan,Bossart, Martin,Vasella, Tomaso,Studer, Armido
, p. 4281 - 4288 (2007/10/03)
Highly diastereoselective radical 1,5 phenyl migration reactions from silicon in diarylsilyl ethers to various C-centered radicals to form the corresponding 3-phenylated alcohols are described. Functionalized aryl groups can also be transferred. The effect of the variation of the attacking radical on the aryl transfer reaction is discussed. Best results are obtained for the phenyl migration to nucleophilic secondary alkyl radicals, where high yields (up to 81%) and high selectivities (up to 95% ds) have been obtained. The mechanism of the process is discussed and a model to explain the stereochemical outcome of the reaction is presented. Finally, stereoselective 1,4 aryl migration reactions from Si to C, including a new method for the α- arylation of esters, are presented.
Ring opening of 1,5-dioxaspiro[3.2]hexanes: Selective preparation of α-heterofunctionalized-β′-hydroxy ketones or 2,2-disubstituted oxetanes
Howell, Amy R.,Ndakala, Albert J.
, p. 825 - 827 (2008/02/09)
(equation presented) 2-Methyleneoxetanes have been converted into 1,5-dioxaspiro[3.2]hexanes with dimethyldioxirane. Reaction of the dioxaspirohexanes with a range of heteroatom nucleophiles, hydride donors, or organoaluminum reagents was successful under
Hindered organoboron groups in organic chemistry. 21. The reactions of dimesitylboron stabilised carbanions with oxiranes
Peter, Andrew,Vaughan-Williams, Gina F.,Rosser, Richard M.
, p. 3007 - 3034 (2007/10/02)
Dimesitylboron stabilised carbanions react with oxiranes to give products that can be oxidised to 1,3-diols. The reactions are, in general, under steric rather than electronic control, and proceed smoothly for all but tetrasubstituted oxiranes. Some unusual stereoselective effects have been observed.
THE DIMESITYLBORON GROUP IN ORGANIC SYNTHESIS 8. PREPARATION OF 1,3-DIOLS FROM OXIRANES
Pelter, Andrew,Bugden, Gina,Rosser, Richard
, p. 5097 - 5100 (2007/10/02)
Alkyldimesitylboranes, yield anions, Mes2BCHR, that on reaction with oxiranes followed by oxidation give 1,3-diols.These anions are thus the operational equivalent of RCHOH.The scope and limitations of the new process are delineated.
