Stereoselectivity and Regioselectivity in the Segment-Coupling Prins Cyclization
作者:James J. Jaber、Kazuhiko Mitsui、Scott D. Rychnovsky
DOI:10.1021/jo010232w
日期:2001.6.1
allylic alcohols leads to fragmentation rather than a disfavored 5-endo-trig cyclization. Dienols in which one alkene is allylic and the other alkene is homoallylic cyclizeefficiently and produce the tetrahydropyrans 49-54, Table 3. Dienols with two homoallylic alkenes cyclize with modest to high regioselectively, generating tetrahydropyrans 40-45, Table 2. The relative rates for cyclization decrease
Basic Al2O3 promotes one-pot synthesis of thioethers via in situ generation and addition of β-acyloxy mercaptans to electron-deficient alkenes
作者:Mohammad Abbasi、Dariush Khalili
DOI:10.1007/s13738-015-0777-7
日期:2016.4
Thioethers were synthesized under solvent-free conditions by reacting Michael acceptors with β-acyloxy mercaptans in situ generated from the reaction of epoxides and thioacids in the presence of basic Al2O3 in high yields.
Kinetic Resolution and Chemoenzymatic Dynamic Kinetic Resolution of Functionalized γ-Hydroxy Amides
作者:Ann-Britt L. Fransson、Linnéa Borén、Oscar Pàmies、Jan-E. Bäckvall
DOI:10.1021/jo0478252
日期:2005.4.1
efficient kineticresolution of racemic γ-hydroxy amides 1 was performed via Pseudomas cepacia lipase (PS-C)-catalyzed transesterification. The enzyme PS-C tolerates both variation in the chain length and different functionalities giving good to high enantioselectivity (E values of up to >250). The combination of enzymatic kineticresolution with a ruthenium-catalyzed racemization led to a dynamic kinetic
Significant rate acceleration in carbonate synthesis from carbon dioxide and oxiranes using dimethyl carbonate as a recyclable medium
作者:Subodh Kumar、Suman L. Jain、Bir Sain
DOI:10.1016/j.tetlet.2011.10.082
日期:2011.12
The synthesis of cyclic carbonates by the reaction of oxiranes and carbon dioxide in the presence of catalytic amount of tetrabutylammonium bromide in dimethylcarbonate without any metal catalyst is reported. Significant rate acceleration in the reaction is observed in dimethylcarbonate as compared to the other solvents. Under the reaction conditions of 100 °C and 2.1 MPa in dimethyl carbonate, maximum