Synthesis of 4-Amino-2(5<i>H</i>)-furanones through Intra- and Intermolecular Nitrile Addition of Ester Enolates. Construction of Carbon Framework of an Antitumor Antibiotic Basidalin
ester group, deprotection, olefin isomerization and lactonization all in a single operation. The other is base-induced ringclosure of α-acyloxy nitriles. The two methods are applied to construction of the carbonframework of an antitumor antibiotic basidalin.
A highlyefficient cyanosilylation protocol mediated by the easily available n-BuLi with a wide range of aldehydes and ketones was developed. This protocol features excellent yields with very low n-BuLi loadings (0.01–0.05 mol%) at room temperature, solvent-free process, good chemo-/regio-selectivity and functional group tolerance and scalability. A possible reaction pathway based upon stoichiometric
Highly enantioselective cyanosilylation of ketones catalyzed by a bifunctional Ti(IV) complex
作者:Ke Shen、Xiaohua Liu、Qinghan Li、Xiaoming Feng
DOI:10.1016/j.tet.2007.10.093
日期:2008.1
A bifunctionalcatalyst system composed of (S)-prolinamide (2a), titanium(IV) isopropoxide, and phenolic N-oxide (3f) exhibited high catalytic efficiency in the enantioselectivecyanosilylation of ketones. In the presence of 2.5 mol % catalyst, a variety of aromatic and aliphatic ketones were converted into the corresponding tertiary cyanohydrin O-TMS ethers in excellent yields (up to 96%) and high
A structurally characterized cationic aluminium complex [(AT)Al(DMAP)]+[OTf]- (3) stabilized through less bulky aminotroponate (AT) ligand is reported (DMAP = 4-(dimethylamino)pyridine). It works as an excellent mononuclear main-group catalyst (1 to 2 mol%) for the cyanosilylation of a variety of aldehydes and ketones by consuming just 5 to 30 min at room temperature.
catalysis promises high catalytic efficiency in the enantioselectivecyanosilylation of ketones through the combined use of a Lewis acid and a Lewis base. Catalyst systems composed of a chiral salen-Al complex and an N-oxide have high catalytic turnovers (200 for aromatic ketones, 1000 for aliphatic ones). With these catalysts, a wide range of aliphatic and aromatic ketones were converted under mild