Efficient acetalisation of aldehydes catalyzed by titanium tetrachloride in a basic medium
作者:Angelo Clerici、Nadia Pastori、Ombretta Porta
DOI:10.1016/s0040-4020(98)00982-x
日期:1998.12
The acetalisation of aliphatic and aromatic aldehydes is achieved in a basic medium by using catalytic amount of Ti(IV) chloride in MeOH in the presence of NH3 or Et3N. The present protocol shows many advantages over the well known base or acid catalysis: in fact, in contrast to base-promoted acetalisation, aldehydes with electron-rich carbonyl groups react easily, enolizable aldehydes do not undergo
Transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones catalysed by natural kaolinitic clay
作者:G. K. Jnaneshwara、N. B. Barhate、A. Sudalai、V. H. Deshpande、R. D. Wakharkar、A. S. Gajare、M. S. Shingare、R. Sukumar
DOI:10.1039/a706475f
日期:——
Natural kaolinitic clay efficiently catalyses the transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones with ethane-1,2-dithiol and propane-1,3-dithiol to produce the corresponding dithiolanes in high yields.
Diastereoselective Prins-Type Reaction of Cycloalkenylcyclopropanol Silyl Ethers and α,β-Unsaturated Aldehyde Acetals
作者:Ivan L. Lysenko、Heong-Sub Oh、Jin Kun Cha
DOI:10.1021/jo071272o
日期:2007.10.1
Electrophilic addition of 1-(1-cyclohexenyl)-1-cyclopropanol trimethylsilylether to α,β-unsaturated aldehyde acetals under Lewisacidic conditions proceeds with good to excellent diastereoselectivity to afford spirocyclobutanones containing three contiguous stereocenters. A convenient entry to enantioselective syntheses is available by use of a nonracemic C2-symmetric acetal. Elaboration of the resulting
Reversing the Regiochemical Course of 1,3-Dipolar Cycloaddition of Nitrile oxides by Modification of Dipolarophiles
作者:Akio Kamimura、Kenzi Hori
DOI:10.1016/s0040-4020(01)85282-0
日期:1994.1
Cycloaddition to the acetal derivatives preferentially gave the regioisomer bearing acetal group on C(4) position. While the opposite regioselectivity was observed for the cycloaddition to dithioacetal derivatives, where the sulfur functional group was mainly located at C(5) position. Theoretical studies on these regiochemical courses showed the C(5) orientation of dithioacetal groups to be directed