Synthesis of Enantiopure 1-Benzyl-2,3-disubstituted Piperazines from Enantiopure p-Toluenesulfinimines
作者:Alma Viso、Roberto Fernández de la Pradilla、María L. López-Rodríguez、Ana García、Mariola Tortosa
DOI:10.1055/s-2002-25336
日期:——
diaminoalcohols with diethyl oxalate and sodium methoxide followed by reduction with BH 3 affords enantiopure 1-benzyl-2,3-disubstituted piperazines. A related sequence produces substituted monoketopiperazines in good yields.
Highly Diastereoselective [3+2] Cycloadditions between Nonracemic p-Tolylsulfinimines and Iminoesters: An Efficient Entry to Enantiopure Imidazolidines and Vicinal Diaminoalcohols
作者:Alma Viso、Roberto Fernández de la Pradilla、Ana García、Carlos Guerrero-Strachan、Marta Alonso、Mariola Tortosa、Aida Flores、Martín Martínez-Ripoll、Isabel Fonseca、Isabelle André、Ana Rodríguez
DOI:10.1002/chem.200204674
日期:2003.6.16
highly diastereoselective process with opposite stereochemistry. Subsequent transformations of the imidazolidines including oxidative, reductive, and hydrolytic processes that provide easy access to vicinal diaminoalcohols have been explored. Among these, reductive cleavage of the aminal with LiAlH4 is an extremely efficient and general reaction for the synthesis of enantiopure N-sulfinyl-N'-benzyldiaminoalcohols
Synthesis of Highly Substituted Enantiopure Piperazines and Ketopiperazines from Vicinal <i>N</i>-Sulfinyl Diamines
作者:Alma Viso、Roberto Fernández de la Pradilla、Aida Flores、Ana García、Mariola Tortosa、María L. López-Rodríguez
DOI:10.1021/jo052077h
日期:2006.2.1
Enantiopure 1-benzyl-2,3-disubstituted piperazines (4) have been synthesized by treatment of N-sulfinyl-N-benzyldiamino alcohols (1) with diethyl oxalate and sodium methoxide followed by reduction with borane. Alternatively, the sulfinamido group was preserved by an N-acylation/cyclization protocol using alpha-chloroacetyl chloride that led to the synthesis of N-sulfinyl ketopiperazines (11). Ensuing elimination of the suffinyl group with NaH produced imino ketopiperazines (9) that are suitably functionalized for nucleophilic addition to the imino moiety. Stereoselective and high yielding allylation of imino ketopiperazines (9c) was achieved under Barbier conditions using CeCl3 center dot 7H(2)O as the additive.