Controlling factors on the stereochemistry of palladium(II)-catalyzed cyclization of 1'-alkyl-4'-chloro-2'-alkenyl 2-alkynoates
摘要:
Beta,gamma-Disubstituted alpha-(Z)-(chloromethylene)-gamma-butyrolactone derivatives have been prepared highly diastereoselectively via a Pd(II)-catalyzed cyclization of 1'-alkyl-4'-chloro-2'-alkenyl 2-alkynoates. Rationales for the stereochemical results of this reaction are proposed.
Lewis Acid Catalyzed Intramolecular Allylic Substitution of Bis(trichloroacetimidates): A Versatile Approach to Racemic Unsaturated Amino Acids
作者:Liene Grigorjeva、Aigars Jirgensons
DOI:10.1002/ejoc.201100060
日期:2011.5
Lewis acid catalyzed cyclization of trichloroacetimidates derived from 1,4-butenediols and 1,5-butenediols was achieved to give 4-vinyl oxazolines and 4-vinyloxazines in good to excellent yields. The cyclization products were transformed to protected unsaturated α- and β-amino acids, thus demonstrating the novel approach to access these important classes of compounds.
Palladium(II)-Catalyzed Highly Regio- and Diastereoselective Cyclization of Difunctional Allylic <i>N</i>-Tosylcarbamates. A Convenient Synthesis of Optically Active 4-Vinyl-2-oxazolidinones and Total Synthesis of 1,4-Dideoxy-1,4-imino-<scp>l</scp>-xylitol
作者:Aiwen Lei、Guosheng Liu、Xiyan Lu
DOI:10.1021/jo0161429
日期:2002.2.1
A Pd(II)-catalyzed cyclization of difunctional allylic N-tosyl carbamates in the presence of halide ions was developed with high regio- and diastereoselectivity. The reaction involves aminopalladation of alkene and beta-heteroatom elimination to regenerate Pd(II) species. When the readily available homochiral alcohols were used as substrates, highly opticallyactive 4-vinyl-2-oxazolidinones were easily
Synthesis of 2-substituted bicyclo[1.1.0]butanes <i>via</i> zincocyclopropanation using bromoform as the carbenoid precursor
作者:Léa Thai-Savard、André B. Charette
DOI:10.1039/d3cc00335c
日期:——
Through a revisited Simmons–Smith type zincocyclopropanation using bromoform as the carbenoid source, the synthesis of 2-, 2,2- and 2,4-substituted bicyclo[1.1.0]butanes is reported. Few antecedents of the derivatives have yet been described. Ultimately, the underexplored scaffolds exhibited a complete discrepency of reactivity.