Helical Chiral 2,2′-Bipyridine N- Monoxides as Catalysts in the Enantioselective Propargylation of Aldehydes with Allenyltrichlorosilane
摘要:
A highly enantioselective synthesis of homopropargylic alcohols is achieved by using the new helical chiral 2,2'-bipyridine N-monoxide catalyst and allenyltrichlorosilane. This method can be further extended to the enantio- and regioselective propargylation of N-acylhydrazones.
importance of London dispersion for structure and stability of molecules with less than about 200 atoms has been established in recent years but the quantitative understanding is still largely based on computations because of a persistent lack of suitable experimental data. We herein report a comprehensive computational and experimental study of the compensation of London dispersion in proton-bound dimer
Deaminative ring contraction for the synthesis of polycyclic heteroaromatics: a concise total synthesis of toddaquinoline
作者:Emily K. Kirkeby、Zachary T. Schwartz、Myles A. Lovasz、Andrew G. Roberts
DOI:10.1039/d3sc03936f
日期:——
A concise strategy to prepare polycyclic heteroaromatics involving a deaminative contraction cascade is detailed. The efficient deaminative ring contraction involves the in situ methylation of a biaryl-linked dihydroazepine to form a cyclic ammonium cation that undergoes a base-induced [1,2]-Stevens rearrangement/dehydroamination sequence. The presence of pseudosymmetry guides the retrosynthetic analysis
The synthesis of four different monoaza[5]helicenes is reported, to complete the whole series of these compounds, so that systematic studies on their properties can be carried out. They were fully characterised via NMR. A theoretical approach to explain why ring closure occurs to give the most crowded compound is reported, in comparison with earlier calculation methods. (c) 2005 Elsevier Ltd. All rights reserved.