Synthesis of Tricyclic Phosphonopyrrolidines via IMDAF: Experimental and Theoretical Investigation of the Observed Stereoselectivity
作者:Diederica D. Claeys、Kristof Moonen、Bart I. Roman、Victor N. Nemykin、Viktor V. Zhdankin、Michel Waroquier、Veronique Van Speybroeck、Christian V. Stevens
DOI:10.1021/jo801138s
日期:2008.10.17
During the synthesis of tricyclic phosphonopyrrolidines via intramolecular Diels-Alder reactions of 1-acylamino(furan-2-yl)methyl phosphonates, two isomers are formed in most cases. The presence of a short three-atom tether together with spectroscopic data, including difference NOE, revealed that the cycloaddition occurred exo, but the phosphonate substituent on the tether had an exo or endo orientation
Experimental and computational study of the ring opening of tricyclic oxanorbornenes to polyhydro isoindole phosphonates
作者:Diederica D. Claeys、Christian V. Stevens、Bart I. Roman、Pieter Van De Caveye、Michel Waroquier、Veronique Van Speybroeck
DOI:10.1039/c002926b
日期:——
Phosphonylated azaheterocycles are an important class of compounds with high biological potential as conformationally restricted bioisosteres of amino acids. Therefore, it is of interest to synthesize conformationally constrained amino phosphonates. We wanted to investigate possible routes via ring opening of α-amino phosphonates with an oxanorbornene skeleton, as these can be synthesized with high stereoselectivity. This was achieved using different Lewis acids, leading to a range of products. The reaction with TiCl4 and FeCl3 was modelled at a DFT level of theory to get insight in the pathways towards the corresponding products. To ease the work up, the Fe(III) catalyst was coated on montmorillonite clay, but this accelerated aromatization after ring opening. Quenching the FeCl3 catalyzed reaction mixture on celite caused complete aromatization.