Stereoselective cyclopropanation of chiral 5-substituted dihydro-2H-piperazines
摘要:
The Simmon-Smith cyclopropanation of enantiomerically enriched dehydropiperazines is reported. The reaction is highly stereoselective and allowed us to prepare new, enantiomerically enriched 3-substituted 2,5-diazabicyclo[4.1.0]heptane cores with high diastereomeric purity and a relative anti-configuration, which was assigned by NMR analysis. (C) 2012 Elsevier Ltd. All rights reserved.
Synthesis of new polysubstituted piperazines and dihydro-2H-pyrazines by selective reduction of 2-oxo-piperazines
摘要:
New enantiomerically enriched 1,4,5-piperazines and 1,4,5-dihydro-2H-pyrazines have been prepared by reduction of the corresponding 2-oxo-piperazines. Selective reduction can be achieved by careful control of the reaction conditions using LiAlH4. Notably the two nitrogen atoms of the final compounds are orthogonally protected. (C) 2010 Elsevier Ltd. All rights reserved.