Lewis Base Catalyzed Enantioselective Allylic Hydroxylation of Morita–Baylis–Hillman Carbonates with Water
摘要:
A Lewis base catalyzed allylic hydroxylation of Morita-Baylis-Hillman (MBH) carbonates has been developed. Various chiral MBH alcohols can be synthesized in high yields (up to 99%) and excellent enantioselectivities (up to 94% ee). This is the first report using water as a nucleophile in asymmetric organocatalysis. The nucleophilic role of water has been verified using O-18-labeling experiments.
Microwave-assisted synthesis of the (E)-α-methylalkenoate framework from multifunctionalized allylic phosphonium salts
作者:Lidiane Meier、Misael Ferreira、Marcus M. Sá
DOI:10.1002/hc.21001
日期:——
A convenient and general microwave-assisted method for the synthesis of stereochemicallydefined α-methylalkenoic acids and esters from allylic phosphonium salts in a basic aqueous medium is described. A selective preparation of acids or esters was dependent on the base (NaOH or NaHCO3) employed in the reaction and could be achieved with good to excellent yields under mild conditions in the absence
an effective means to convert methyl 2‐(azidomethyl)‐3‐arylpropenoates and 2‐(azidomethyl)‐3‐arylacrylonitriles to the corresponding iminyl radicals via α‐hydrogenabstraction and subsequent extrusion of dinitrogen. Thus formed iminyl radicals then undergo intramolecular ortho attack on the aryl ring, affording methyl quinoline‐3‐carboxylates and quinoline‐3‐carbonitriles respectively.
An expedient stereoselective synthesis of (Z)- and (E)-allyl iodides from Baylis–Hillman adducts along with selective iodination of benzylic alcohols using the polymethylhydrosiloxane–iodine system
A stereoselective method has been developed for the synthesis of (Z)- and (E)-allyl iodides from Baylis–Hillman adducts using polymethylhydrosiloxane (PMHS) and iodine in chloroform at room temperature. In addition, the reagent system has been utilized for the iodination of benzylic alcohols selectively.
The use of star-like polyionic Lewis base heterogeneous nanocatalyst for the Baylis–Hillman reaction of benzyl- and methylacrylates with aryl aldehydes has been investigated. The corresponding Baylis–Hillman adducts are obtained in good to high yields in one-pot procedure at room temperature in 5.5–8 h. The catalyst can be easily recovered with excellent purity by filtration and can be reused directly without any change in its catalytic activity.
One-pot easy conversion of Baylis–Hillman adducts into carbamates of unsaturated β-amino acids
作者:Manouchehr Mamaghani、Abed Badrian
DOI:10.1016/j.tetlet.2003.12.046
日期:2004.2
An easy, one-pot transformation of Baylis–Hillman adducts into carbamates of unsaturated β-amino acids, for example, 2-(aryl(methoxycarbonylamino)methyl)acrylic acid methyl esters 7 and 2-(methoxycarbonyl aminomethyl)-3-arylacrylic acid methyl esters 8 via reaction with the Burgess reagent is described.